Engineer, Institut National Agronomique (2017)
Doctor of Philosophy, Universite Du Quebec (2022)
Master of Science, Universite De Paris Vi (2017)
Doctor of Philosophy, Université du Québec à Montréal (Montréal, Canada), Biochemsitry (2022)
Food industry engineer, AgroParisTech (Paris, France) (2017)
Lynette Cegelski, Postdoctoral Faculty Sponsor
Peculiar Phosphonate Modifications of Velvet Worm Slime Revealed by Advanced Nuclear Magnetic Resonance and Mass Spectrometry.
Journal of the American Chemical Society
Nature is rich with examples of highly specialized biological materials produced by organisms for functions, including defense, hunting, and protection. Along these lines, velvet worms (Onychophora) expel a protein-based slime used for hunting and defense that upon shearing and dehydration forms fibers as stiff as thermoplastics. These fibers can dissolve back into their precursor proteins in water, after which they can be drawn into new fibers, providing biological inspiration to design recyclable materials. Elevated phosphorus content in velvet worm slime was previously observed and putatively ascribed to protein phosphorylation. Here, we show instead that phosphorus is primarily present as phosphonate moieties in the slime of distantly related velvet worm species. Using high-resolution nuclear magnetic resonance (NMR), natural abundance dynamic nuclear polarization (DNP), and mass spectrometry (MS), we demonstrate that 2-aminoethyl phosphonate (2-AEP) is associated with glycans linked to large slime proteins, while transcriptomic analyses confirm the expression of 2-AEP synthesizing enzymes in slime glands. The evolutionary conservation of this rare protein modification suggests an essential functional role of phosphonates in velvet worm slime and should stimulate further study of the function of this unusual chemical modification in nature.
View details for DOI 10.1021/jacs.3c06798
View details for PubMedID 37722679
The Internal Structure of the Velvet Worm Projectile Slime: A Small-Angle Scattering Study.
Small (Weinheim an der Bergstrasse, Germany)
For prey capture and defense, velvet worms eject an adhesive slime which has been established as a model system for recyclable complex liquids. Triggered by mechanical agitation, the liquid bio-adhesive rapidly transitions into solid fibers. In order to understand this mechanoresponsive behavior, here, the nanostructural organization of slime components are studied using small-angle scattering with neutrons and X-rays. The scattering intensities are successfully described with a three-component model accounting for proteins of two dominant molecular weight fractions and nanoscale globules. In contrast to the previous assumption that high molecular weight proteins-the presumed building blocks of the fiber core-are contained in the nanoglobules, it is found that the majority of slime proteins exist freely in solution. Only less than 10% of the slime proteins are contained in the nanoglobules, necessitating a reassessment of their function in fiber formation. Comparing scattering data of slime re-hydrated with light and heavy water reveals that the majority of lipids in slime are contained in the nanoglobules with homogeneous distribution. Vibrating mechanical impact under exclusion of air neither leads to formation of fibers nor alters the bulk structure of slime significantly, suggesting that interfacial phenomena and directional shearing are required for fiberformation.
View details for DOI 10.1002/smll.202300516
View details for PubMedID 36828797
Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants
Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.
View details for DOI 10.1021/acs.chemrev.1c00669
View details for Web of Science ID 000731592900001
View details for PubMedID 34878762
View details for PubMedCentralID PMC9486976
Identification and Quantification of Glycans in Whole Cells: Architecture of Microalgal Polysaccharides Described by Solid-State Nuclear Magnetic Resonance
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
2021; 143 (46): 19374-19388
Microalgae are photosynthetic organisms widely distributed in nature and serve as a sustainable source of bioproducts. Their carbohydrate components are also promising candidates for bioenergy production and bioremediation, but the structural characterization of these heterogeneous polymers in cells remains a formidable problem. Here we present a widely applicable protocol for identifying and quantifying the glycan content using magic-angle-spinning (MAS) solid-state NMR (ssNMR) spectroscopy, with validation from glycosyl linkage and composition analysis deduced from mass-spectrometry (MS). Two-dimensional 13C-13C correlation ssNMR spectra of a uniformly 13C-labeled green microalga Parachlorella beijerinckii reveal that starch is the most abundant polysaccharide in a naturally cellulose-deficient strain, and this polymer adopts a well-organized and highly rigid structure in the cell. Some xyloses are present in both the mobile and rigid domains of the cell wall, with their chemical shifts partially aligned with the flat-ribbon 2-fold xylan identified in plants. Surprisingly, most other carbohydrates are largely mobile, regardless of their distribution in glycolipids or cell walls. These structural insights correlate with the high digestibility of this cellulose-deficient strain, and the in-cell ssNMR methods will facilitate the investigations of other economically important algae species.
View details for DOI 10.1021/jacs.1c07429
View details for Web of Science ID 000750614100007
View details for PubMedID 34735142
View details for PubMedCentralID PMC8630702
Effects of polydopamine-passivation on the optical properties of carbon dots and its potential usein vivo
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
2020; 22 (29): 16595-16605
Passivation of carbon dots via heteroatom doping has been shown to enhance their optical properties and tune their fluorescence signature. Additionally, the incorporation of polymeric precursors in carbon dot synthesis has gained considerable interest with benefits to biological applications namely bioimaging, drug delivery and sensing, among others. In order to combine the desirable attributes of both, fluorescence enhancement and increased biocompatibility, polymers composed of high aromaticity and nitrogen content can be used as efficient carbon dot passivating agents. Here, the synthesis of fluorescent polymer-passivated carbon dots was developed through a microwave-assisted pyrolysis reaction of galactose, citric acid and polydopamine. Passivation of the dots with polydopamine induces a 90 nm red-shift in the fluorescence maxima from 420 to 510 nm. Moreover, passivation results in excitation-independent fluorescence and a 3.5-fold increase in fluorescence quantum yield, which increases from 1.3 to 4.6%. The application of the carbon dots as imaging probes was investigated in in vitro and in vivo model systems. Cytotoxicity studies in J774 and CHO-K1 cell lines revealed reduced cell toxicity for the polydopamine-passivated carbon dots in comparison to their unpassivated counterpart. In BALB/c mice, biodistribution studies demonstrated that regardless of surface passivation, the dots predominantly remained in the circulatory system 90 minutes post inoculation suggesting their potential use for cardiovascular therapies.
View details for DOI 10.1039/d0cp01938k
View details for Web of Science ID 000556485900007
View details for PubMedID 32666968
Unambiguous Ex Situ and in Cell 2D C-13 Solid-State NMR Characterization of Starch and Its Constituents
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
2018; 19 (12)
Starch is the most abundant energy storage molecule in plants and is an essential part of the human diet. This glucose polymer is composed of amorphous and crystalline domains in different forms (A and B types) with specific physicochemical properties that determine its bioavailability for an organism, as well as its value in the food industry. Using two-dimensional (2D) high resolution solid-state nuclear magnetic resonance (SS-NMR) on 13C-labelled starches that were obtained from Chlamydomonas reinhardtii microalgae, we established a complete and unambiguous assignment for starch and its constituents (amylopectin and amylose) in the two crystalline forms and in the amorphous state. We also assigned so far unreported non-reducing end groups and assessed starch chain length, crystallinity and amylose content. Starch was then characterized in situ, i.e., by 13C solid-state NMR of intact microalgal cells. Our in-cell methodology also enabled the identification of the effect of nitrogen starvation on starch metabolism. This work shows how solid-state NMR can enable the identification of starch structure, chemical modifications and biosynthesis in situ in intact microorganisms, eliminating time consuming and potentially altering purification steps.
View details for DOI 10.3390/ijms19123817
View details for Web of Science ID 000455323500119
View details for PubMedID 30513587
View details for PubMedCentralID PMC6320826