Aakriti Gangwal

All Publications

• Synthesis, structure-activity relationships, and SARS-CoV-2 antiviral activity of 3,5-disubstituted isothiazolo[4,3-b]pyridines as PIKfyve inhibitors. Frontiers in chemistry Gao, L. J., Kalebic, D., Lo, C. W., Gangwal, A., Tran, D. H., Rozenski, J., Schols, D., Froeyen, M., Dehaen, W., Einav, S., De Jonghe, S. 2026; 14: 1777981

  Abstract

  3-Alkynyl-6-aryl-isothiazolo[4,3-b]pyridines have previously been shown to be potent inhibitors of the lipid kinase FYVE finger-containing phosphoinositide kinase (PIKfyve), displaying broad-spectrum antiviral activity.To further study their structure-activity relationship (SAR), an efficient synthesis toward 3- bromo-5-chloro-isothiazolo[4,3-b]pyridine was established. It allowed to introduce structural modifications at positions 3 and 5 by palladium-catalyzed cross-coupling reactions and nucleophilic aromatic substitutions.It led to the generation of a focused library of 3,5-disubstituted isothiazolo[4,3-b]pyridines. Several derivatives exhibited potent PIKfyve inhibition (in the low nM range) in a biochemical assay and antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (in the low μM range). To gain an insight in their binding mode, molecular modeling was applied, indicating that these 3,5- disubstituted isothiazolo[4,3-b]pyridines bind to the ATP-binding site of PIKfyve, although with a different binding mode from that of the 3,6- disubstituted isothiazolo[4,3-b]pyridines.

  View details for DOI 10.3389/fchem.2026.1777981

  View details for PubMedID 42179838

  View details for PubMedCentralID PMC13194157

• Role of Post-Translational Modifications in Virulence of Bacillus anthracis: A narrative review. Research in microbiology Baweja, R., Rajput, H., Bhardwaj, P., Gangwal, A., Balaji, B. S., Singh, Y. 2025: 104344

  Abstract

  Bacillus anthracis, a rod-shaped, spore-forming bacterium, is the causative agent of anthrax. The life cycle of B. anthracis involves sporulation and germination processes that are precisely regulated by distinct sigma factors and associated proteins. Its pathogenicity is primarily attributed to a tripartite toxin consisting of lethal factor (LF), edema factor (EF) and protective antigen (PA), as well as an antiphagocytic capsule of Poly-γ-D-Glutamate. The virulence of B. anthracis is further regulated by various post-translational modifications (PTMs), including protein phosphorylation, acetylation, glycosylation, hydroxylation, and lipidation. These modifications play a key role in modulating bacterial virulence by influencing enzymatic activity and protein expression. This review summarizes the role of PTMs in the regulation of B. anthracis virulence. A deeper understanding of how these PTMs contribute to B. anthracis pathogenesis may offer new insights into novel enzyme targets, strategies to disrupt toxin production and the development of therapeutic approaches to combat anthrax infections.

  View details for DOI 10.1016/j.resmic.2025.104344

  View details for PubMedID 41038412

• A novel AAA+ ATPase required for sporulation and stress response in Bacillus anthracis. bioRxiv : the preprint server for biology Sangwan, N., Bothra, A., Pomerantsev, A. P., Gangwal, A., Fattah, R., Moayeri, M., Ma, Q., Ganesan, S., Keshavam, C. C., Baweja, R., Dhawan, U., Leppla, S. H., Singh, Y. 2025

  Abstract

  AAA+ proteins function as molecular machines that utilize ATP to perform diverse cellular functions, including protein homeostasis, stress regulation, and cell cycle/developmental processes. In this study, we identified a novel AAA+ ATPase BAS PrkA in B. anthracis Sterne 34F2 which has 88 % protein homology to Bacillus subtilis PrkA. Conserved domain analysis confirms BAS PrkA has an N-terminal AAA+ ATPase domain with characteristic Walker A and Walker B motifs and a conserved secondary region of homology (SRH) domain, along with a C-terminal cAMP-dependent protein kinase domain. Based on Alpha Fold3 predicted structure, we classified BAS PrkA as part of Clade III of the AAA+ superfamily. Contrary to the reported enzymatic activity in B. subtilis PrkA, we observed that BAS PrkA has negligible protease and kinase activity under in-vitro conditions. Nonetheless, BAS PrkA plays a significant role in regulating sporulation. It is temporally expressed during Stages II to VI during sporulation. A null mutant of BAS PrkA exhibits severe sporulation defects, with reduced spore viability, and down regulation of genes related to spore-coat formation. These phenotypes were restored in a complementation strain expressing BAS PrkA ectopically. Additionally, the null mutant strain showed compromised growth under ionic-osmotic stress conditions. Analysis of the BAS PrkA interactome revealed enrichment of two proteins, ProA and EzrA, that are implicated in osmotic stress response and the sporulation process, respectively. These findings show that BAS PrkA plays a critical role in sporulation and osmotic stress response in B. anthracis .

  View details for DOI 10.1101/2025.06.16.659970

  View details for PubMedID 40568155

  View details for PubMedCentralID PMC12190318

• Anthrax: Transmission, Pathogenesis, Prevention and Treatment. Toxins Sangwan, N., Gangwal, A., Jain, P., Langtso, C., Srivastava, S., Dhawan, U., Baweja, R., Singh, Y. 2025; 17 (2)

  Abstract

  Bacillus anthracis is a deadly pathogen that under unfavourable conditions forms highly resistant spores which enable them to survive for a long period of time. Spores of B. anthracis are transmitted through the contaminated soil or animal products and enter to the host through the skin, lungs or oral route and can cause cutaneous, injection, inhalation and gastrointestinal anthrax, respectively. The disease is caused by the toxin which is produced by them once they germinate within the host cell. Anthrax toxin is the major virulence factor which has the ability to kill the host cell. The role of protein kinases and phosphatases of B. anthracis in toxin production and other virulence related properties have also been reported. There are two vaccines, BioThrax and CYFENDUSTM, which are approved by the FDA-USA to prevent anthrax disease. Recently, anthrax toxin has also been shown to be a potential candidate for cancer therapeutics. Through present review, we aim to provide insights into sporulation, transmission and pathogenesis of B. anthracis as well as the current state of its prevention, treatment, vaccines and possible therapeutic uses in cancer.

  View details for DOI 10.3390/toxins17020056

  View details for PubMedID 39998073

• The heparin-binding hemagglutinin protein of Mycobacterium tuberculosis is a nucleoid-associated protein. The Journal of biological chemistry Keshavam, C. C., Naz, S., Gupta, A., Sanyal, P., Kochar, M., Gangwal, A., Sangwan, N., Kumar, N., Tyagi, E., Goel, S., Singh, N. K., Sowpati, D. T., Khare, G., Ganguli, M., Raze, D., Locht, C., Basu-Modak, S., Gupta, M., Nandicoori, V. K., Singh, Y. 2023; 299 (12): 105364

  Abstract

  Nucleoid-associated proteins (NAPs) regulate multiple cellular processes such as gene expression, virulence, and dormancy throughout bacterial species. NAPs help in the survival and adaptation of Mycobacterium tuberculosis (Mtb) within the host. Fourteen NAPs have been identified in Escherichia coli; however, only seven NAPs are documented in Mtb. Given its complex lifestyle, it is reasonable to assume that Mtb would encode for more NAPs. Using bioinformatics tools and biochemical experiments, we have identified the heparin-binding hemagglutinin (HbhA) protein of Mtb as a novel sequence-independent DNA-binding protein which has previously been characterized as an adhesion molecule required for extrapulmonary dissemination. Deleting the carboxy-terminal domain of HbhA resulted in a complete loss of its DNA-binding activity. Atomic force microscopy showed HbhA-mediated architectural modulations in the DNA, which may play a regulatory role in transcription and genome organization. Our results showed that HbhA colocalizes with the nucleoid region of Mtb. Transcriptomics analyses of a hbhA KO strain revealed that it regulates the expression of ∼36% of total and ∼29% of essential genes. Deletion of hbhA resulted in the upregulation of ∼73% of all differentially expressed genes, belonging to multiple pathways suggesting it to be a global repressor. The results show that HbhA is a nonessential NAP regulating gene expression globally and acting as a plausible transcriptional repressor.

  View details for DOI 10.1016/j.jbc.2023.105364

  View details for PubMedID 37865319

  View details for PubMedCentralID PMC10665949

• Giving a signal: how protein phosphorylation helps Bacillus navigate through different life stages. FEMS microbiology reviews Gangwal, A., Kumar, N., Sangwan, N., Dhasmana, N., Dhawan, U., Sajid, A., Arora, G., Singh, Y. 2023; 47 (4)

  Abstract

  Protein phosphorylation is a universal mechanism regulating a wide range of cellular responses across all domains of life. The antagonistic activities of kinases and phosphatases can orchestrate the life cycle of an organism. The availability of bacterial genome sequences, particularly Bacillus species, followed by proteomics and functional studies have aided in the identification of putative protein kinases and protein phosphatases, and their downstream substrates. Several studies have established the role of phosphorylation in different physiological states of Bacillus species as they pass through various life stages such as sporulation, germination, and biofilm formation. The most common phosphorylation sites in Bacillus proteins are histidine, aspartate, tyrosine, serine, threonine, and arginine residues. Protein phosphorylation can alter protein activity, structural conformation, and protein-protein interactions, ultimately affecting the downstream pathways. In this review, we summarize the knowledge available in the field of Bacillus signaling, with a focus on the role of protein phosphorylation in its physiological processes.

  View details for DOI 10.1093/femsre/fuad044

  View details for PubMedID 37533212

  View details for PubMedCentralID PMC10465088

• Role of serine/threonine protein phosphatase PrpN in the life cycle of Bacillus anthracis. PLoS pathogens Gangwal, A., Sangwan, N., Dhasmana, N., Kumar, N., Keshavam, C. C., Singh, L. K., Bothra, A., Goel, A. K., Pomerantsev, A. P., Leppla, S. H., Singh, Y. 2022; 18 (8): e1010729

  Abstract

  Reversible protein phosphorylation at serine/threonine residues is one of the most common protein modifications, widely observed in all kingdoms of life. The catalysts controlling this modification are specific serine/threonine kinases and phosphatases that modulate various cellular pathways ranging from growth to cellular death. Genome sequencing and various omics studies have led to the identification of numerous serine/threonine kinases and cognate phosphatases, yet the physiological relevance of many of these proteins remain enigmatic. In Bacillus anthracis, only one ser/thr phosphatase, PrpC, has been functionally characterized; it was reported to be non-essential for bacterial growth and survival. In the present study, we characterized another ser/thr phosphatase (PrpN) of B. anthracis by various structural and functional approaches. To examine its physiological relevance in B. anthracis, a null mutant strain of prpN was generated and shown to have defects in sporulation and reduced synthesis of toxins (PA and LF) and the toxin activator protein AtxA. We also identified CodY, a global transcriptional regulator, as a target of PrpN and ser/thr kinase PrkC. CodY phosphorylation strongly controlled its binding to the promoter region of atxA, as shown using phosphomimetic and phosphoablative mutants. In nutshell, the present study reports phosphorylation-mediated regulation of CodY activity in the context of anthrax toxin synthesis in B. anthracis by a previously uncharacterized ser/thr protein phosphatase-PrpN.

  View details for DOI 10.1371/journal.ppat.1010729

  View details for PubMedID 35913993

  View details for PubMedCentralID PMC9371265

• Bacillus anthracis chain length, a virulence determinant, is regulated by membrane localized serine/threonine protein kinase PrkC. Journal of bacteriology Dhasmana, N., Kumar, N., Gangwal, A., Keshavam, C. C., Singh, L. K., Sangwan, N., Nashier, P., Biswas, S., Pomerantsev, A. P., Leppla, S. H., Singh, Y., Gupta, M. 2021; 203 (11)

  Abstract

  Anthrax is a zoonotic disease caused by Bacillus anthracis, a spore-forming pathogen that displays a chaining phenotype. It has been reported that the chaining phenotype acts as a virulence factor in B. anthracis In this study, we identify a serine/threonine protein kinase of B. anthracis, PrkC, the only kinase localized at the bacteria-host interface, as a determinant of B. anthracis chain length. In vitro, prkC disruption strain (BAS ΔprkC) grew as shorter chains throughout the bacterial growth cycle. A comparative analysis between the parent strain and BAS ΔprkC indicated that the levels of proteins, BslO and Sap, associated with the regulation of the bacterial chain length, were upregulated in BAS ΔprkC BslO is a septal murein hydrolase that catalyzes daughter cell separation and Sap is an S-layer structural protein required for the septal localization of BslO. PrkC disruption also has a significant effect on bacterial growth, cell wall thickness, and septa formation. Upregulation of ftsZ in BAS ΔprkC was also observed. Altogether, our results indicate that PrkC is required for maintaining optimum growth, cell wall homeostasis and most importantly - for the maintenance of the chaining phenotype.IMPORTANCEChaining phenotype acts as a virulence factor in Bacillus anthracis This is the first study that identifies a 'signal transduction protein' with an ability to regulate the chaining phenotype in Bacillus anthracis We show that the disruption of the lone surface-localized serine/threonine protein kinase, PrkC, leads to the shortening of the bacterial chains. We report upregulation of the de-chaining proteins in the PrkC disruption strain. Apart from this, we also report for the first time that PrkC disruption results in an attenuated cell growth, a decrease in the cell wall thickness and aberrant cell septa formation during the logarithmic phase of growth - a growth phase where PrkC is expressed maximally.

  View details for DOI 10.1128/JB.00582-20

  View details for PubMedID 33753466

  View details for PubMedCentralID PMC8117516

• ClpC-Mediated Sporulation Regulation at Engulfment Stage in Bacillus anthracis. Indian journal of microbiology Kumar, N., Gangwal, A., Sangwan, N., Dhasmana, N., Keshavam, C. C., Tyagi, E., Singh, Y. 2021; 61 (2): 170-179

  Abstract

  Bacterial sporulation is a conserved process utilized by members of Bacillus genus and Clostridium in response to stress such as nutrient or temperature. Sporulation initiation is triggered by stress signals perceived by bacterial cell that leads to shutdown of metabolic pathways of bacterial cells. The mechanism of sporulation involves a complex network that is regulated at various checkpoints to form the viable bacterial spore. Engulfment is one such check point that drives the required cellular rearrangement necessary for the spore assembly and is mediated by bacterial proteolytic machinery that involves association of various Clp ATPases and ClpP protease. The present study highlights the importance of degradation of an anti-sigma factor F, SpoIIAB by ClpCP proteolytic machinery playing a crucial role in culmination of engulfment process during the sporulation in Bacillus anthracis.

  View details for DOI 10.1007/s12088-021-00927-5

  View details for PubMedID 33927458

  View details for PubMedCentralID PMC8039082

• Bacterial Virulence Factors: Secreted for Survival. Indian journal of microbiology Sharma, A. K., Dhasmana, N., Dubey, N., Kumar, N., Gangwal, A., Gupta, M., Singh, Y. 2017; 57 (1): 1-10

  Abstract

  Virulence is described as an ability of an organism to infect the host and cause a disease. Virulence factors are the molecules that assist the bacterium colonize the host at the cellular level. These factors are either secretory, membrane associated or cytosolic in nature. The cytosolic factors facilitate the bacterium to undergo quick adaptive-metabolic, physiological and morphological shifts. The membrane associated virulence factors aid the bacterium in adhesion and evasion of the host cell. The secretory factors are important components of bacterial armoury which help the bacterium wade through the innate and adaptive immune response mounted within the host. In extracellular pathogens, the secretory virulence factors act synergistically to kill the host cells. In this review, we revisit the role of some of the secreted virulence factors of two human pathogens: Mycobacterium tuberculosis-an intracellular pathogen and Bacillus anthracis-an extracellular pathogen. The advances in research on the role of secretory factors of these pathogens during infection are discussed.

  View details for DOI 10.1007/s12088-016-0625-1

  View details for PubMedID 28148975

  View details for PubMedCentralID PMC5243249

• Serine/Threonine Protein Phosphatase PstP of Mycobacterium tuberculosis Is Necessary for Accurate Cell Division and Survival of Pathogen. The Journal of biological chemistry Sharma, A. K., Arora, D., Singh, L. K., Gangwal, A., Sajid, A., Molle, V., Singh, Y., Nandicoori, V. K. 2016; 291 (46): 24215-24230

  Abstract

  Protein phosphatases play vital roles in phosphorylation-mediated cellular signaling. Although there are 11 serine/threonine protein kinases in Mycobacterium tuberculosis, only one serine/threonine phosphatase, PstP, has been identified. Although PstP has been biochemically characterized and multiple in vitro substrates have been identified, its physiological role has not yet been elucidated. In this study, we have investigated the impact of PstP on cell growth and survival of the pathogen in the host. Overexpression of PstP led to elongated cells and partially compromised survival. We find that depletion of PstP is detrimental to cell survival, eventually leading to cell death. PstP depletion results in elongated multiseptate cells, suggesting a role for PstP in regulating cell division events. Complementation experiments performed with PstP deletion mutants revealed marginally compromised survival, suggesting that all of the domains, including the extracellular domain, are necessary for complete rescue. On the other hand, the catalytic activity of PstP is absolutely essential for the in vitro growth. Mice infection experiments establish a definitive role for PstP in pathogen survival within the host. Depletion of PstP from established infections causes pathogen clearance, indicating that the continued presence of PstP is necessary for pathogen survival. Taken together, our data suggest an important role for PstP in establishing and maintaining infection, possibly via the modulation of cell division events.

  View details for DOI 10.1074/jbc.M116.754531

  View details for PubMedID 27758870

  View details for PubMedCentralID PMC5104944