logo Insalogo Insa

Hélène MARTIN-YKENChargée de Recherches LISBP


Chargée de Recherches
Equipe Physiologie Moléculaire des Eucaryotes
+33 (0)562250132
INSA de Toulouse
135 avenue de Rangueil
31077 Toulouse cedex 4 - FRANCE



PhD in Biochemistry
Date of birth: April 23th 1972
Nationality: French.

1995 : Engineering Diploma from the National Institute of Applied Sciences (INSA) specialty: Biochemistry and Molecular biology (1rst of promotion).
1998 : PhD Thesis from the National Institute of Applied Sciences (INSA)/ Paul Sabatier University, Toulouse, France.
1999-2000 : Post-doc position in the lab of Pr. David Levin, Johns Hopkins University, Baltimore, Maryland (USA).
2001 : Researcher at National Institute of Agronomic Research (INRA), LISBP, Toulouse.





Cell Wall Synthesis and Cell Integrity Maintenance in response to Stress in the model yeast S. cerevisiae.

Our team uses complementary approaches such as genomics, proteomics, fluxomics, microbiology and classical molecular biology techniques, as well as genetics and analytical biochemistry to study various aspects of stress response in the model budding yeast Saccharomyces cerevisiae. I am specifically investigating the mechanisms of cell integrity maintenance and cell wall adaptation upon heat shock,mechanical or osmotic stress and exposure to several drugs (Martin-Yken et al.,2003, Basmaji et al., 2008, Dagkessamanskaia et al., 2010,…).
Yeast cell walls are essential for the maintenance of cell shape, prevention of lysis, and regulation of the uptake of substances from the medium. In Saccharomyces cerevisiae, the cell wall is a complex structure composed of mannoproteins, β-1,3-glucan, and β-1,6-glucan, and chitin (a N-acetylglucosamine polymer) cross-linked to each other. This rigid structure is in fact highly dynamic at the molecular level, and gets remodeled for morphogentic events such as budding, mating, and sporulation to take place, and is also quickly adapted in response to environmental changes. We studied these mechanisms at the biochemical and molecular levels (Lagorce et al., 2003, Durand et al., 2008, Dagkessamanskaia et al., 2010-2) and we are currently investigating the biophysics of yeast cell wall using Atomic Force Microscopy (AFM) (Dague et al., 2010).
AFM is a remarkably powerful tool, allowing us to get images of the cell surface topology at the nanoscale and to measure physical characteristics of the cell wall (roughness, elasticity) as well as interaction forces between cellular components. In addition, it provides a true ‘physical visualization’ of how molecular events -that were previously characterized only chemically- actually take place in the cell wall. We have thus used AFM technology to characterize the effects on cell wall of several stresses (François et al., 2013, Curr. Genet.), including heat shock (Pillet et al., 2014, BMC Biology), Caspofungin treatment (Formosa et al., 2013, A. A. C.) and exposure to Killer toxin (Liu et al., 2015, App. Lett. NanoBioScience).
Moreover, we are now developing new strategies using AFM to perform Single Molecule Force Spectroscopy (SMFS) in order to detect and map out receptors, enzymes, adhesins, or any other molecules at the surface of living cells. We have successfully mapped Ha-tagged proteins at the surface of different cell types, including living S. cerevisiae yeast cells undergoing sexual differentiation (Formosa et al., 2015,J. Mol. Rec.). We have also been able to characterize the adhesion pattern of C. albicans cells specifically overexpressing adhesins of interest (Cabral, 2015. PLoS Path.)


Stochastic Fluctuations in Gene expression and their relations to Stress Adaptation and Evolution

I am also involved in a different project, which aims at studying the role of variability of gene expression (due to the stochastic fluctuations at the molecular level) in stress response and genetic instability. The impact of this variability on population dynamics is now well-studied, and increase of stochasticity (or noise) of gene expression is considered as a relevant evolutionary strategy in fluctuating environments. Here we want to determine if such an increase for some genes has been a way for technological yeast strains to adapt to the stressful fluctuating conditions they have to deal with. Indeed, these strains are well-adapted to many environmental stress compared to laboratory strains. To start with this project, we have used a recently sequenced oenological strain of Saccharomyces cerevisiae EC1118 to detect promoters that are noisier in this strain compared to the standard non-adapted laboratory strain S288c. We are now analysing the differences of noise between these promoter variants, before studying their impact on stress response and adaptation in stressful environments, especially in terms of fitness. Through this study we were able to identify new determinants of stress resistance and tolerance (Liu et al., 2015-2).



Most Recent Publications:
Liu J., C. Formosa, Schiavone M., Dague E., François J.M. and Martin-Yken H. 2015. Combining Atomic Force Microscopy and genetics to investigate the role of Knr4 in Saccharomyces cerevisiae sensitivity to K9 Killer toxin. Letters in Applied NanoBioScience, (In press).
Liu J., Martin-Yken H., Bigey F., Dequin S., François J.M., Capp J.P.. Genome Biology and Evolution. 2015. Natural yeast promoter variants reveal epistasis in the generation of transcriptional-mediated noise and its potential benefit in stressful conditions.; DOI:10.1093/gbe/evv047
Formosa C., Lachaize V., Galés C., Rols M.P., Martin‐Yken H., François J.M., Duval R.E., Dague E. 2015. Mapping HA-tagged protein at the surface of living cells by atomic force microscopy. Journal of Molecular Recognition; 28(1). DOI:10.1002/jmr.2407
V. Cabral, Znaidi S., Walker L. A, Martin-Yken H., Dague E., Legrand M., Lee K., Chauvel M., Firon A., Rossignol T., Richard M. L, Munro C. A, Bachellier-Bassi S., d'Enfert Ch.. 2015. PLoS Pathogens. Targeted Changes of the Cell Wall Proteome Influence Candida albicans Ability to Form Single- and Multi-strain Biofilms.
Walther T., Létisse F., Peyriga L., Alkim C., Liu Y., Lardenois A., Martin-Yken H., Portais J.C., Primig M., François J. M.. BMC Biology . 2014. 12(1):60. Developmental stage dependent metabolic regulation during meiotic differentiation in budding yeast. DOI:10.1186/s12915-014-0060
Schiavone M., Vax A., Formosa C., Martin‐Yken H., Dague E., François J.M.. 2014. FEMS Yeast Research 14(6). A combined chemical and
enzymatic method to determine quantitatively the polysaccharide components in the cell wall of yeasts. DOI:10.1111/1567-1364.12182
Pillet F., Lemonier S., Schiavone M., Formosa C., Martin-Yken H., Francois J. M., Dague E.. 2014. BMC Biology . 12(1):6. Uncovering by Atomic Force Microscopy of an original circular structure at the yeast cell surface in response to heat shock. DOI:10.1186/1741-7007-12-6
François J.M., C. Formosa, Schiavone M., Pillet F., Martin-Yken H., Dague E. 2013. Current Genetics. Use of atomic force microscopy (AFM) to explore cell wall properties and response to stress in the yeast Saccharomyces cerevisiae. DOI:10.1007/s00294-013-0411-0
Formosa C., Schiavone M., Martin-Yken H., François J. M., Duval R. E., Dague E. 2013. Antimicrobial Agents and Chemotherapy; 57(8). Nanoscale Effects of Caspofungin against Two Yeast Species, Saccharomyces cerevisiae and Candida albicans. DOI:10.1128/AAC.00105-13
H. Martin-Yken, Ribaud V., Poli J., Hoareau-Aveilla C., Spichal M., Beaufort S., Tilloy V., Delerue T., Capp J-P., Parrou J-L.. 2012. 10th Francophone Yeast Meeting 'Levures, Modèles & Outils'. Research in Microbiology; 163(5):309-15. DOI:10.1016/j.resmic.2012.05.007
Dagkessamanskaia A., El Azzouzi K., Kikuchi Y., Timmers T., Ohya Y., François J. and Martin-Yken H. 2010, Knr4 N-terminal domain controls its localization and function during sexual differentiation and vegetative growth, Yeast, 27(8), 563-74.
Dagkessamanskaia A., Durand F., Uversky V.N., Binda M., Lopez F., El Azzouzi K., Francois J., Martin-Yken H. 2010, Functional dissection of an intrinsically disordered protein: understanding the roles of different domains of Knr4 protein in protein-protein interactions. Protein Sci, 19(7):1376-85.
Dague E., Bitar R., Ranchon H., Durand F, Martin-Yken H, and François J., 2010, An atomic force microscopy analysis of yeast mutants defective in cell wall architecture. Yeast, 27(8), 673-84.
Durand F, Dagkessamanskaia A, Martin-Yken H, Graille M, Van Tilbeurgh H, Uversky VN, François J., 2008, Structure-function analysis of Knr4/Smi1, a newly member of intrinsically disordered proteins family, indispensable in the absence of a functional PKC1-SLT2 pathway in Saccharomyces cerevisiae. Yeast, 25(8):563-76.
Basmaji F., Martin-Yken H., Durand F., Pichereaux C., Rossignol M. and. François J, 2006. The ‘interactome” of the Knr4/Smi1, a protein implicated
in coordinating cell wall assembly with cellular growth in Saccharomyces cerevisiae. Mol Gen.Genomics, 275(3) : 217-30.
Guillemot G., Vaca-Medina G., Martin-Yken H., Vernhet A., Schmitz P. and Mercier-Bonin M., 2006. Elucidating strong adhesion of Saccharomyces cerevisiae to stainless steel. Colloids and Surfaces-B : Bio-interfaces, 49(2) : 126-35.
Martin-Yken H., Dagkessamanskaia A., Basmaji F., Lagorce A., and François J. 2003. The interaction of Slt2 MAP kinase with Knr4 is necessary for signalling through the cell wall integrity pathway in Saccharomyces cerevisiae. Mol. Microbiol. 49(1), 23-35.
Lagorce A., Hauser N., Labourdette D., Rodriguez C., Martin-Yken H., Arroyo J., Hoheisel J. and François J. 2003. Genome wide analysis of the response to cell wall mutations in the yeast Saccharomyces cerevisiae. J Biol Chem, 278 (22), 20345-20357
Martin-Yken H., Lagorce A. and François, J. 2003. The yeast Sacharomyces cerevisiae Cell Wall : Molecular architecture, regulatory pathways and remodelling in response to environmental conditions and biotechnological values. “Recent Research Developments in Microbiology”, 6, 503-525.
Total number of international publications or communications: 35.