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Hélène Marquis

 

 

Helene Marquis Photo

Associate Professor of Microbiology

Cornell University College of Veterinary Medicine
C5 169 Veterinary Medical Center
E-mail: hm72@cornell.edu
Phone: 607-253-3273

DVM (University of Montreal)
PhD (Texas A&M University)


Dr. Marquis is an associate professor of Microbiology and Immunology. She received a doctorate degree in Veterinary Medicine from the University of Montréal in Canada and was awarded a Ph.D. in Veterinary Microbiology from Texas A&M University for her studies on the outer membrane proteins of Brucella spp. with Dr. Thomas Ficht. She was a post-doctoral fellow in the laboratory of Dr. Daniel Portnoy at the University of Pennsylvania, working on the pathogenesis of Listeria monocytogenes. In 1997, she assumed a position of assistant professor in the Department of Microbiology at the University of Colorado School of Medicine. She moved to Cornell University in July 2001.


 Research Interests | Graduate Fields | Lab Members | Related Links | Selected References

Research Interests

The study of intracellular microbial pathogens allows a multidisciplinary approach to fundamental questions related to host cell/microbe interactions. My laboratory is studying the facultative intracellular Gram-positive bacterium Listeria monocytogenes. During infection, L. monocytogenes resides in the cytosol of infected cells and spreads from cell to cell without leaving the intracellular milieu. We are presently pursuing three projects in the lab: (1) Proprotein secretion in monoderm Gram-positive bacteria; (2) Modulation of innate immunity by a bacterial phospholipase; and (3) Listeria-based vaccine for cutaneous leishmaniasis.

Text Box:      Model of PC-PLC and Mpl maturation and secretion by L. monocytogenes  Proprotein secretion in monoderm Gram-positive bacteria. The broad-range phospholipase C of L. monocytogenes (PC-PLC) contributes to bacterial escape from vacuoles formed upon cell-to-cell spread.  PC-PLC is made as a proenzyme whose activation is mediated by a metalloprotease (Mpl).  Mpl is also made as a proenzyme whose activation occurs by autocatalysis.  We showed that intracellular bacteria carry a pool of Mpl and PC-PLC within the inner wall zone, and that a decrease in vacuolar pH leads to the activation and secretion of both enzymes across the cell wall.  We are interested in defining at the molecular and biochemical levels the mechanism(s) regulating the secretion of proproteins made by monoderm Gram-positive bacteria.

Modulation of innate immunity by a bacterial phospholipase. A mutant of L. monocytogenes that has lost the ability to regulate PC-PLC activity is strongly attenuated in the mouse. We are investigating the mechanism by which PC-PLC compromises the virulence of L. monocytogenes.

Listeria-based vaccine for cutaneous leishmaniasis. In this project, we are using L. monocytogenes to deliver sandfly salivary gland antigens in the cytosol of infected cells, aiming at stimulating a rapid immune response upon transmission of Leishmania by sandflies.


Graduate Fields

Dr. Marquis is a member of the following Graduate Fields:

dot Comparative Biomedical Sciences
dot Food Science and Technology
dot Immunology and Infecitous Disease
dot Microbiology


Lab Members

Kelsey Goldbeck, Lab Technical Support (kcg48@cornell.edu)

Related Links

dot Program in Infection and Pathobiology
dot Program in Bacterial Pathogenesis
dot Graduate Program in Biological and Biomedical Sciences
dot Seminars in Infection and Immunity: Fall, Spring

 

Selected References

O’Neil, H.S., B.M. Forster, K.L. Roberts, A.J. Chambers, A.P. Bitar, and H. Marquis. 2009. The propeptide of the metalloprotease of Listeria monocytogenes controls compartmentalization of the zymogen during intracellular infection. J. Bacteriol. 191:3594-3603.

Zemansky, J., B.C. Kline, J.J. Woodward, J.H. Leber, H. Marquis, and D.A. Portnoy. 2009. Development of a mariner-based transposon and identification of Listeria monocytogenes determinants, including the peptidyl-prolyl isomerase PrsA2, that contribute to its hemolytic activity. J. Bacteriol. 191:3950-3964.

Xayarath, B., H. Marquis, G. C. Port, and N. E. Freitag. 2009. Listeria monocytogenes CtaP is a multifunctional cysteine transport-associated protein required for bacterial pathogenesis. Mol Microbiol. 74:956-973.

Slepkov, E.R., A. Pavinski Bitar, and H. Marquis. 2010. Differentiation of propeptide residues regulating the compartmentalization, maturation and activity of the broad-range phospholipase C of Listeria monocytogenes. Biochem. J. 432:557-563.

Forster, B.M., A. Pavinski Bitar, E.R. Slepkov, K.J. Kota, H. Sondermann, and H. Marquis. 2011. The metalloprotease of Listeria monocytogenes is regulated by pH. J. Bacteriol. 193:5090-5097.

Forster, B.M., J. Zemansky, D.A. Portnoy, and H. Marquis. 2011. The post-translocation chaperone PrsA2 regulates the maturation and secretion of Listeria monocytogenes proprotein virulence factors. J. Bacteriol. 193:5961-5970.

Foster, B.M. and H. Marquis. 2012. Protein transport across the cell wall of monoderm Gram-positive bacteria. Mol. Microbiol. 84:405-413.