- MSMEG_1963 and MSMEG_5597 Genes, but Not inhA, Modulate Mycobacterium smegmatis Resistance to Tryptanthrins RUSSIAN JOURNAL OF GENETICS 2022; 58 (9): 1051-1058
Arabinosyltransferase C Mediates Multiple Drugs Intrinsic Resistance by Altering Cell Envelope Permeability in Mycobacterium abscessus
Mycobacterium abscessus is an emerging human pathogen leading to significant morbidity and even mortality, intrinsically resistant to almost all the antibiotics available and so can be a nightmare. Mechanisms of its intrinsic resistance remain not fully understood. Here, we selected and confirmed an M. abscessus transposon mutant that is hypersensitive to multiple drugs including rifampin, rifabutin, vancomycin, clofazimine, linezolid, imipenem, levofloxacin, cefoxitin, and clarithromycin. The gene MAB_0189c encoding a putative arabinosyltransferase C was found to be disrupted, using a newly developed highly-efficient strategy combining next-generation sequencing and multiple PCR. Furthermore, selectable marker-free deletion of MAB_0189c recapitulated the hypersensitive phenotype. Disruption of MAB_0189c resulted in an inability to synthesize lipoarabinomannan and markedly enhanced its cell envelope permeability. Complementing MAB_0189c or M. tuberculosis embC restored the resistance phenotype. Importantly, treatment of M. abscessus with ethambutol, a first-line antituberculosis drug targeting arabinosyltransferases of M. tuberculosis, largely sensitized M. abscessus to multiple antibiotics in vitro. We finally tested activities of six selected drugs using a murine model of sustained M. abscessus infection and found that linezolid, rifabutin, and imipenem were active against the MAB_0189c deletion strain. These results identified MAB_0189 as a crucial determinant of intrinsic resistance of M. abscessus, and optimizing inhibitors targeting MAB_0189 might be a strategy to disarm the intrinsic multiple antibiotic resistance of M. abscessus. IMPORTANCE Mycobacterium abscessus is intrinsically resistant to most antibiotics, and treatment of its infections is highly challenging. The mechanisms of its intrinsic resistance remain not fully understood. Here we found a transposon mutant hypersensitive to a variety of drugs and identified the transposon inserted into the MAB_0189c (orthologous embC coding arabinosyltransferase, EmbC) gene by using a newly developed rapid and efficient approach. We further verified that the MAB_0189c gene played a significant role in its intrinsic resistance by decreasing the cell envelope permeability through affecting the production of lipoarabinomannan in its cell envelope. Lastly, we found the arabinosyltransferases inhibitor, ethambutol, increased activities of nine selected drugs in vitro. Knockout of MAB_0189c made M. abscessus become susceptible to 3 drugs in mice. These findings indicated that potential powerful M. abscessus EmbC inhibitor might be used to reverse the intrinsic resistance of M. abscessus to multiple drugs.
View details for DOI 10.1128/spectrum.02763-21
View details for Web of Science ID 000839516600001
View details for PubMedID 35946941
View details for PubMedCentralID PMC9430846
Synthesis and Characterization of Novel 2-Acyl-3-trifluoromethylquinoxaline 1,4-Dioxides as Potential Antimicrobial Agents
2022; 15 (2)
The emergence of drug resistance in pathogens leads to a loss of effectiveness of antimicrobials and complicates the treatment of bacterial infections. Quinoxaline 1,4-dioxides represent a prospective scaffold for search of new compounds with improved chemotherapeutic characteristics. Novel 2-acyl-3-trifluoromethylquinoxaline 1,4-dioxides with alteration of substituents at position 2 and 6 were synthesized via nucleophilic substitution with piperazine moiety and evaluated against a broad panel of bacteria and fungi by measuring their minimal inhibitory concentrations. Their mode of action was assessed by whole-genomic sequencing of spontaneous drug-resistant Mycobacterium smegmatis mutants, followed by comparative genomic analysis, and on an original pDualrep2 system. Most of the 2-acyl-3-trifluoromethylquinoxaline 1,4-dioxides showed high antibacterial properties against Gram-positive strains, including mycobacteria, and the introduction of a halogen atom in the position 6 of the quinoxaline ring further increased their activity, with 13c being the most active compound. The mode of action studies confirmed the DNA-damaging nature of the obtained quinoxaline 1,4-dioxides, while drug-resistance may be provided by mutations in redox homeostasis genes, encoding enzymes potentially involved in the activation of the compounds. This study extends views about the antimicrobial and antifungal activities of the quinoxaline 1,4-dioxides and can potentially lead to the discovery of new antibacterial drugs.
View details for DOI 10.3390/ph15020155
View details for Web of Science ID 000761447000001
View details for PubMedID 35215268
View details for PubMedCentralID PMC8877263
Repurposing Based Identification of Novel Inhibitors against MmpS5-MmpL5 Efflux Pump of Mycobacterium smegmatis: A Combined In Silico and In Vitro Study
2022; 10 (2)
In the current era of a pandemic, infections of COVID-19 and Tuberculosis (TB) enhance the detrimental effects of both diseases in suffering individuals. The resistance mechanisms evolving in Mycobacterium tuberculosis are limiting the efficiency of current therapeutic measures and pressurizing the stressed medical infrastructures. The bacterial efflux pumps enable the development of resistance against recently approved drugs such as bedaquiline and clofazimine. Consequently, the MmpS5-MmpL5 protein system was selected because of its role in efflux pumping of anti-TB drugs. The MmpS5-MmpL5 systems of Mycobacterium smegmatis were modelled and the virtual screening was performed using an ASINEX library of 5968 anti-bacterial compounds. The inhibitors with the highest binding affinities and QSAR based highest predicted inhibitory concentration were selected. The MmpS5-MmpL5 associated systems with BDE_26593610 and BDD_27860195 showed highest inhibitory parameters. These were subjected to 100 ns Molecular Dynamics simulations and provided the validation regarding the interaction studies. The in vitro studies demonstrated that the BDE_26593610 and BDD_27860195 can be considered as active inhibitors for M. smegmatis MmpS5-MmpL5. The outcomes of this study can be utilized in other experimentation aimed at drug design and discovery against the drug resistance strains of M. tuberculosis.
View details for DOI 10.3390/biomedicines10020333
View details for Web of Science ID 000763949700001
View details for PubMedID 35203542
View details for PubMedCentralID PMC8869396
Characterization of Genetic Variants Associated with Rifampicin Resistance Level in Mycobacterium tuberculosis Clinical Isolates Collected in Guangzhou Chest Hospital, China
INFECTION AND DRUG RESISTANCE
2022; 15: 5655-5666
Rifampicin (RIF)-resistance, a surrogate marker for multidrug-resistant tuberculosis (TB), is mediated by mutations in the rpoB gene. We aimed to investigate the prevalence of mutations pattern in the entire rpoB gene of Mycobacterium tuberculosis clinical isolates and their association with resistance level to RIF.Among 465 clinical isolates collected from the Guangzhou Chest Hospital, drug-susceptibility of 175 confirmed Mtb strains was performed via the proportion method and Bactec MGIT 960 system. GeneXpert MTB/RIF and sanger sequencing facilitated in genetic characterization, whereas the MICs of RIF were determined by Alamar blue assay.We found 150/175 (85.71%) RIF-resistant strains (MIC: 4 to >64 µg/mL) of which 57 were MDR and 81 pre-XDR TB. Genetic analysis identified 17 types of mutations 146/150 (97.33%) within RRDR (codons 426-452) of rpoB, mainly at L430 (P), D435 (V, E, G, N), H445 (N, D, Y, R, L), S450 (L, F) and L452 (P). D435V 12/146 (8.2%), H445N 16/146 (10.9%), and S450L 70/146 (47.94%) were the most frequently encountered mutations. Mutations Q432K, M434V, and N437D are rarely identified in RRDR. Deletions at (1284-1289 CCAGCT), (1295-1303 AATTCATGG), and insertion at (1300-1302 TTC) were detected within RRDR of three RIFR strains for the first time. We detected 47 types of mutations and insertions/deletions (indels) outside the RRDR. Four RIFR strains were detected with only novel mutations/indels outside the RRDR. Two of the four had (K274Q + C897 del + I491M) and (A286V + L494P), respectively. The other two had (G1687del + P454L) and (TT1835-6 ins + I491L) individually. Compared with phenotypic characterization, diagnostic sensitivities of GeneXpert MTB/RIF and sequencing analysis were 95.33% (143/150), and 100% (150/150) respectively.Our findings underscore the key role of RRDR mutations and the contribution of non-RRDR mutations in rapid molecular diagnosis of RIFR clinical isolates. Such insights will support early detection of disease and recommend the appropriate anti-TB regimens in high-burden settings.
View details for DOI 10.2147/IDR.S375869
View details for Web of Science ID 000862514400001
View details for PubMedID 36193294
View details for PubMedCentralID PMC9526423
Sterilizing Effects of Novel Regimens Containing TB47, Clofazimine, and Linezolid in a Murine Model of Tuberculosis.
Antimicrobial agents and chemotherapy
2021; 65 (10): e0070621
TB47, a new drug candidate targeting QcrB in the electron transport chain, has shown a unique synergistic activity with clofazimine and forms a highly sterilizing combination. Here, we investigated the sterilizing effects of several all-oral regimens containing TB47 plus clofazimine and linezolid as a block and the roles of fluoroquinolones and pyrazinamide in them. All these regimens cured tuberculosis within 4 to 6 months in a well-established mouse model, and adding pyrazinamide showed a significant difference in bactericidal effects.
View details for DOI 10.1128/AAC.00706-21
View details for PubMedID 34280022
View details for PubMedCentralID PMC8448087
Transcriptomic Profile of Mycobacterium smegmatis in Response to an Imidazo[1,2-b][1,2,4,5]tetrazine Reveals Its Possible Impact on Iron Metabolism.
Frontiers in microbiology
2021; 12: 724042
Tuberculosis (TB), caused by the Mycobacterium tuberculosis complex bacteria, is one of the most pressing health problems. The development of new drugs and new therapeutic regimens effective against the pathogen is one of the greatest challenges in the way of tuberculosis control. Imidazo[1,2-b][1,2,4,5]tetrazines have shown promising activity against M. tuberculosis and M. smegmatis strains. Mutations in MSMEG_1380 lead to mmpS5-mmpL5 operon overexpression, which provides M. smegmatis with efflux-mediated resistance to imidazo[1,2-b][1,2,4,5]tetrazines, but the exact mechanism of action of these compounds remains unknown. To assess the mode of action of imidazo[1,2-b][1,2,4,5]tetrazines, we analyzed the transcriptomic response of M. smegmatis to three different concentrations of 3a compound: 1/8×, 1/4×, and 1/2× MIC. Six groups of genes responsible for siderophore synthesis and transport were upregulated in a dose-dependent manner, while virtual docking revealed proteins involved in siderophore synthesis as possible targets for 3a. Thus, we suggest that imidazo[1,2-b][1,2,4,5]tetrazines may affect mycobacterial iron metabolism.
View details for DOI 10.3389/fmicb.2021.724042
View details for PubMedID 34421882
View details for PubMedCentralID PMC8371482
Identification of Mutations Conferring Tryptanthrin Resistance to Mycobacterium smegmatis.
Antibiotics (Basel, Switzerland)
2020; 10 (1)
Tuberculosis (TB), caused by Mycobacterium tuberculosis, is a global burden, responsible for over 1 million deaths annually. The emergence and spread of drug-resistant M. tuberculosis strains (MDR-, XDR- and TDR-TB) is the main challenge in global TB-control, requiring the development of novel drugs acting on new biotargets, thus able to overcome the drug-resistance. Tryptanthrin is a natural alkaloid, with great therapeutic potential due to its simple way of synthesis and wide spectrum of biological activities including high bactericidal activity on both drug-susceptible and MDR M. tuberculosis strains. InhA was suggested as the target of tryptanthrins by in silico modeling, making it a promising alternative to isoniazid, able to overcome drug resistance provided by katG mutations. However, neither the mechanism of action of tryptanthrin nor the mechanism of resistance to tryptanthrins was ever confirmed in vitro. We show that the MmpS5-MmpL5 efflux system is able to provide resistance to tryptanthrins using an in-house test-system. Comparative genomic analysis of spontaneous tryptanthrin-resistant M. smegmatis mutants showed that mutations in MSMEG_1963 (EmbR transcriptional regulator) lead to a high-level resistance, while those in MSMEG_5597 (TetR transcriptional regulator) to a low-level one. Mutations in an MFS transporter gene (MSMEG_4427) were also observed, which might be involved in providing a basal level of tryptanthrins-resistance.
View details for DOI 10.3390/antibiotics10010006
View details for PubMedID 33374765
View details for PubMedCentralID PMC7823563
Transcriptomic dataset of Mycolicibacterium smegmatis exposed to an imidazo[1,2-b][1,2,4,5]tetrazine.
Data in brief
2020; 31: 105805
Deciphering the mechanism of action of novel anti-tuberculosis compounds is a key step in the drug development process. We have previously described a number of imidazo[1,2-b][1,2,4,5]tetrazines with a promising activity on Mycobacterium tuberculosis. These compounds had predicted activity as serine‑threonine protein kinase inhibitors, however spontaneous drug resistant Mycolicibacterium smegmatis mc 2 155 (formerly Mycobacterium smegmatis) revealed only the mycobacterial mechanism of resistance to imidazo[1,2-b][1,2,4,5]tetrazines: mutations in MSMEG_1380 gene lead to overexpression of the mmpS5-mmpL5 operon in M. smegmatis, thus providing resistance to imidazo[1,2-b][1,2,4,5]tetrazines via enhanced efflux . Here we report the RNA sequencing data of M. smegmatis mc 2 155 culture treated with one of the imidazo[1,2-b][1,2,4,5]tetrazines for 1.5 h and the untreated culture as a control. The mapped reads showed that a total of 1386 genes are differentially expressed in this experiment. A further analysis of these data can shed light of the mechanism of action of imidazo[1,2-b][1,2,4,5]tetrazines. The data generated by RNA-seq (raw reads) have been deposited to NCBI sequence read archive (SRA) and have been assigned a BioProject accession number PRJNA615922.
View details for DOI 10.1016/j.dib.2020.105805
View details for PubMedID 32566706
View details for PubMedCentralID PMC7298395
Transcriptional regulation of drug resistance mechanisms in Salmonella: where we stand and what we need to know.
World journal of microbiology & biotechnology
2020; 36 (6): 85
Salmonellae have evolved a wide range of molecular mechanisms to neutralize the effect of antibiotics and evade the host immune system response. These mechanisms are exquisitely controlled by global and local regulators and enable the pathogens to use its energy as per need and hence allow the pathogen to economize the consumption of energy by its cellular machinery. Several families that regulate the expression of different drug resistance genes are known; some of these are: the TetR family (which affects tetracycline resistance genes), the AraC/XylS family (regulators that can act as both transcriptional activators and repressors), two-component signal transduction systems (e.g. PhoPQ, a key regulator for virulence), mercury resistance Mer-R and multiple antibiotic resistance Mar-R regulators, LysR-type global regulators (e.g. LeuO) and histone-like protein regulators (involved in the repression of newly transferred resistance genes). This minireview focuses on the role of different regulators harbored by the Salmonella genome and characterized for mediating the drug resistance mechanisms particularly via efflux and influx systems. Understanding of such transcriptional regulation mechanisms is imperative to address drug resistance issues in Salmonella and other bacterial pathogens.
View details for DOI 10.1007/s11274-020-02862-x
View details for PubMedID 32468234
MmpS5-MmpL5 Transporters Provide Mycobacterium smegmatis Resistance to imidazo[1,2-b][1,2,4,5]tetrazines.
Pathogens (Basel, Switzerland)
2020; 9 (3)
The emergence and spread of drug-resistant Mycobacterium tuberculosis strains (including MDR, XDR, and TDR) force scientists worldwide to search for new anti-tuberculosis drugs. We have previously reported a number of imidazo[1,2-b][1,2,4,5]tetrazines - putative inhibitors of mycobacterial eukaryotic-type serine-threonine protein-kinases, active against M. tuberculosis. Whole genomic sequences of spontaneous drug-resistant M. smegmatis mutants revealed four genes possibly involved in imidazo[1,2-b][1,2,4,5]tetrazines resistance; however, the exact mechanism of resistance remain unknown. We used different approaches (construction of targeted mutants, overexpression of the wild-type (w.t.) and mutant genes, and gene-expression studies) to assess the role of the previously identified mutations. We show that mutations in MSMEG_1380 gene lead to overexpression of the mmpS5-mmpL5 operon in M. smegmatis, thus providing resistance to imidazo[1,2-b][1,2,4,5]tetrazines by increased efflux through the MmpS5-MmpL5 system, similarly to the mechanisms of resistance described for M. tuberculosis and M. abscessus. Mycobacterial MmpS5-MmpL5 transporters should be considered as an MDR-efflux system and they should be taken into account at early stages of anti-tuberculosis drug development.
View details for DOI 10.3390/pathogens9030166
View details for PubMedID 32121069
View details for PubMedCentralID PMC7157563
Draft Genome Sequences of Mycobacterium tuberculosis Clinical Isolates from the Ural Region of Russia That Carry the pks15/1 Gene.
Microbiology resource announcements
2019; 8 (49)
Here, we report the draft genome sequences of 15 Mycobacterium tuberculosis isolates of the Beijing-B0/W-148 sublineage that carry a 7-bp insertion within the pks15 gene, which leads to the synthesis of Pks15/1 fusion protein. Pks15/1 is involved in phenolglycolipid synthesis and biofilm formation, thus potentially contributing to the B0/W-148 lineage's enhanced virulence and drug resistance.
View details for DOI 10.1128/MRA.01126-19
View details for PubMedID 31806743
View details for PubMedCentralID PMC6895303
Sequencing and Analysis of Three Mycobacterium tuberculosis Genomes of the B0/N-90 Sublineage.
Microbiology resource announcements
2019; 8 (39)
We report the draft genome sequences of three Mycobacterium tuberculosis isolates belonging to the B0/N-90 sublineage, EKB34, EKB53, and EKB79. The B0/N-90 sublineage belongs to the prevalent (in Russia) and highly virulent Beijing-B0/W148 sublineage. Isolates EKB34 and EKB79 were obtained from people with immune deficiency.
View details for DOI 10.1128/MRA.00796-19
View details for PubMedID 31558630
View details for PubMedCentralID PMC6763645
Synthesis and antimycobacterial activity of imidazo[1,2-b][1,2,4,5]tetrazines.
European journal of medicinal chemistry
2019; 178: 39-47
Tuberculosis (TB) has recently become the leading killer among infectious diseases. Multidrug and extensively drug-resistant Mycobacterium tuberculosis strains urge the need to develop anti-TB drugs with a novel mechanism of action. We describe synthesis of 22 novel imidazo[1,2-b][1,2,4,5]tetrazine derivatives with different substituents at C(3) and C(6) positions, and their antimycobacterial activity in vitro. 8 compounds show activity as potential serine/threonine protein kinase (STPK) inhibitors in M. smegmatis aphVIII+ test-system, which is characteristic for this class. 3 compounds out of 5 most active STPK inhibitors have a prominent minimal inhibitory concentration on M. tuberculosis H37Rv of 1 μg/ml. We were able to obtain M. smegmatis mc2 155 mutants resistant to 4 compounds and show that they do not have cross resistance with other drugs, but have a common mechanism of resistance among these 4 imidazo[1,2-b][1,2,4,5]tetrazines. Compound 3h seems the most promising, combining a predicted STPK inhibitor activity, the lowest MIC on M. tuberculosis and a low frequency of drug resistant mutants' emergence.
View details for DOI 10.1016/j.ejmech.2019.05.081
View details for PubMedID 31176094
Draft Genome Sequences of 12 Mycolicibacterium smegmatis Strains Resistant to Imidazo[1,2-b][1,2,4,5]Tetrazines.
Microbiology resource announcements
2019; 8 (16)
Here, we report 12 draft genome sequences of mutant Mycolicibacterium smegmatis strains resistant to imidazo[1,2-b][1,2,4,5]tetrazines, which are antituberculosis drug candidates. We have identified 7 different mutations in the MSMEG_1380 gene, which encodes the AcrR/TetR_N transcriptional repressor, which may activate efflux-mediated resistance.
View details for DOI 10.1128/MRA.00263-19
View details for PubMedID 31000553
View details for PubMedCentralID PMC6473147
Mutations in Efflux Pump Rv1258c (Tap) Cause Resistance to Pyrazinamide, Isoniazid, and Streptomycin in M. tuberculosis.
Frontiers in microbiology
2019; 10: 216
Although drug resistance in Mycobacterium tuberculosis is mainly caused by mutations in drug activating enzymes or drug targets, there is increasing interest in the possible role of efflux in causing drug resistance. Previously, efflux genes have been shown to be upregulated upon drug exposure or implicated in drug resistance in overexpression studies, but the role of mutations in efflux pumps identified in clinical isolates in causing drug resistance is unknown. Here we investigated the role of mutations in efflux pump Rv1258c (Tap) from clinical isolates in causing drug resistance in M. tuberculosis. We constructed point mutations V219A and S292L in Rv1258c in the chromosome of M. tuberculosis and the point mutations were confirmed by DNA sequencing. The susceptibility of the constructed M. tuberculosis Rv1258c mutants to different tuberculosis drugs was assessed using conventional drug susceptibility testing in 7H11 agar in the presence and absence of efflux pump inhibitor piperine. A C14-labeled PZA uptake experiment was performed to demonstrate higher efflux activity in the M. tuberculosis Rv1258c mutants. Interestingly, the V219A and S292L point mutations caused clinically relevant drug resistance to pyrazinamide (PZA), isoniazid (INH), and streptomycin (SM), but not to other drugs in M. tuberculosis. While V219A point mutation conferred low-level drug resistance, the S292L mutation caused a higher level of resistance. Efflux inhibitor piperine inhibited INH and PZA resistance in the S292L mutant but not in the V219A mutant. The S292L mutant had higher efflux activity for pyrazinoic acid (the active form of PZA) than the parent strain. We conclude that point mutations in the efflux pump Rv1258c in clinical isolates can confer clinically relevant drug resistance, including PZA resistance, and could explain some previously unaccounted drug resistance in clinical strains. Future studies need to take efflux mutations into consideration for improved detection of drug resistance in M. tuberculosis and address their role in affecting treatment outcome in vivo.
View details for DOI 10.3389/fmicb.2019.00216
View details for PubMedID 30837962
View details for PubMedCentralID PMC6389670
- Genetic Aspects of Drug Resistance and Virulence in Mycobacterium tuberculosis RUSSIAN JOURNAL OF GENETICS 2018; 54 (12): 1385-1396
- MYCOBACTERIUM TUBERCULOSIS: DRUG RESISTANCE, VIRULENCE AND POSSIBLE SOLUTIONS BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2018: 5-12
- WHOLE-GENOME SEQUENCING AND COMPARATIVE GENOMIC ANALYSIS OF MYCOBACTERIUM SMEGMATIS MUTANTS RESISTANT TO IMIDAZO[1,2-b][1,2,4,5]TETRAZINES, ANTITUBERCULOSIS DRUG CANDIDATES BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2018: 19-22
- COMPILATION OF THE MYCOBACTERIUM TUBERCULOSIS BEIJING-B0 LINEAGE SAMPLE AND IDENTIFYING PREDICTORS OF IMMUNE DYSFUNCTION IN SOURCE PATIENTS BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2018: 23-28
- Tuberculostatic Activity of 2-Amino-6-Chloropurine Derivatives PHARMACEUTICAL CHEMISTRY JOURNAL 2017; 51 (9): 769-772
- The Intrinsic Antibiotic Resistance to beta-Lactams, Macrolides, and Fluoroquinolones of Mycobacteria Is Mediated by the whiB7 and tap Genes RUSSIAN JOURNAL OF GENETICS 2017; 53 (9): 1006-1015
- MIRU-VNTR GENOTYPING OF MYCOBACTERIUM TUBERCULOSIS CLINICAL ISOLATES FROM MOSCOW REGION BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2017: 44-47
AMINOPYRIDINE- AND AMINOPYRIMIDINE-BASED SERINE/THREONINE PROTEIN KINASE INHIBITORS ARE DRUG CANDIDATES FOR TREATING DRUG-RESISTANT TUBERCULOSIS
BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY
View details for Web of Science ID 000453123600004
Resistance to pyrazinamide in Russian Mycobacterium tuberculosis isolates: pncA sequencing versus Bactec MGIT 960.
Tuberculosis (Edinburgh, Scotland)
2015; 95 (5): 608-12
Resistance to pyrazinamide (PZA) may impact clinical outcome of anti-tuberculosis chemotherapy. PZA susceptibility testing using MGIT 960 is not reliable and little information is available on the prevalence of PZA resistance in Russia. A collection of 64 clinical isolates of Mycobacterium tuberculosis, including 35 multidrug resistant and extensively drug-resistant (MDR/XDR), was analyzed for PZA resistance using MGIT 960, Wayne test, and sequencing of PZA resistance genes pncA, rpsA and panD. In addition, we analyzed 519 MDR-TB strains for susceptibility to PZA by MGIT 960. Sequencing of pncA revealed 17 of 25 (68%) MDR strains and all 10 XDR strains harboring pncA mutations. A correlation of φ = 0.81 between MGIT 960 and pncA sequencing was observed. Mutations in rpsA and panD not associated with PZA resistance as defined by MGIT 960 were identified. We found 1 PZA-resistant strain without mutations in known PZA resistance genes. Almost 73% of MDR-TB strains isolated in Moscow, Russia, were PZA-resistant by MGIT 960 testing of 519 MDR-TB clinical isolates. Further studies are needed to determine the role of rpsA and panD mutations in possible low-level PZA resistance and to identify the molecular basis of new PZA resistance in the isolate without known PZA resistance mutations.
View details for DOI 10.1016/j.tube.2015.05.013
View details for PubMedID 26071666
- Synthesis and activity of (+)-usnic acid and (-)-usnic acid derivatives containing 1,3-thiazole cycle against Mycobacterium tuberculosis MEDICINAL CHEMISTRY RESEARCH 2015; 24 (7): 2926-2938
Draft Genome Sequences of Two Pyrazinamide-Resistant Clinical Isolates, Mycobacterium tuberculosis 13-4152 and 13-2459
2015; 3 (4)
We report draft genome sequences of two pyrazinamide (PZA)-resistant isolates, Mycobacterium tuberculosis 13-4152 and 13-2459. Isolate 13-4152 is PZA resistant, though it lacks mutations in known genes of PZA resistance. The comparative analysis of these genomes with those stored in GenBank revealed unique mutations, which may elucidate new mechanisms of PZA resistance.
View details for DOI 10.1128/genomeA.00758-15
View details for Web of Science ID 000460635800052
View details for PubMedID 26139726
View details for PubMedCentralID PMC4490854
Draft Genome Sequence of Mycobacterium tuberculosis Strain E186hv of Beijing B0/W Lineage with Reduced Virulence
2015; 3 (3)
We report a draft genome sequence of Mycobacterium tuberculosis strain E186hv, belonging to the Beijing B0/W lineage and isolated from a patient from Kurgan, Russia. This clinical isolate showed a reduced virulence phenotype unusual for this lineage and resistance to isoniazid, rifampin, ethambutol, pyrazinamide, and ofloxacin. We analyzed single nucleotide polymorphisms (SNPs) associated with virulence.
View details for DOI 10.1128/genomeA.00403-15
View details for Web of Science ID 000460631200042
View details for PubMedID 25953188
View details for PubMedCentralID PMC4424304
Identification of phosphorylation sites in aminoglycoside phosphotransferase VIII from Streptomyces rimosus
2012; 77 (11): 1258-1265
We demonstrate for the first time the role of phosphorylation in the regulation of activities of enzymes responsible for inactivation of aminoglycoside antibiotics. The aminoglycoside phosphotransferase VIII (APHVIII) from the actinobacterial strain Streptomyces rimosus ATCC 10970 is an enzyme regulated by protein kinases. Two serine residues in APHVIII are shown to be phosphorylated by protein kinases from extracts of the kanamycin-resistant strain S. rimosus 683 (a derivative of strain ATCC 10970). Using site-directed mutagenesis and molecular modeling, we have identified the Ser146 residue in the activation loop of the enzyme as the key site for Ca2+-dependent phosphorylation of APHVIII. Comparison of the kanamycin kinase activities of the unphosphorylated and phosphorylated forms of the initial and mutant APHVIII shows that the Ser146 modification leads to a 6-7-fold increase in the kanamycin kinase activity of APHVIII. Thus, Ser146 in the activation loop of APHVIII is crucial for the enzyme activity. The resistance of bacterial cells to kanamycin increases proportionally. From the practical viewpoint, our results increase prospects for creation of highly effective test systems for selecting inhibitors of human and bacterial serine/threonine protein kinases based on APHVIII constructs and corresponding human and bacterial serine/threonine protein kinases.
View details for DOI 10.1134/S0006297912110041
View details for Web of Science ID 000311331800004
View details for PubMedID 23240563