Molecular Biology
of Corynebacteria and Mycobacteria

Mycobacteria and Corynebacteria are diderm Gram positive bacteria with a very impermeable cell envelope composed of a very thick complex of peptidoglycan arabinogalactan and mycolic acids.

Our group is focused on the structure, organization and mechanism of assembly of this unique envelope whose function is essential for viability.

Project

Corynebacteriales are an order of actinomycetes that includes corynebacteria, mycobacteria, nocardia, rhodococci and other related microorganisms. Some species, e.g. Mycobacterium tuberculosis, Mycobacterium leprae, are known to cause severe infectious diseases in humans, while others are of considerable economic benefit like Corynebacterium glutamicum, the world’s largest producer of glutamate and lysine.

Organisation of {Corynebacteriales} cell envelope

The cell envelope of Corynebacteriales has a complex and unusual structure that possesses features of both Gram-positive and Gram-negative bacteria. The cell wall core of these bacteria is made up of a specific matrix composed of cross-linked peptidoglycan (PG) covalently bound to arabinogalactan chains (AG), which in turn are linked to long chain fatty acids (up to 90 carbon atoms in mycobacteria) and named mycolic acids (MA), allowing the attached lipids to form with other trehalose mycolates an outer membrane (mycomembrane). Our group played a significant role in the identification and biochemical characterization of this mycomembrane in C. glutamicum during the last decade (for example: Zuber et al. 2008, Marchand et al. 2012).

The biosynthesis of individual MA and AG cell wall compounds has been studied for a long time primarily because the production of these compounds is essential for mycobacterial survival. As a matter of fact, the AG and MA synthesis is the target of several known antituberculous drugs, e.g. isoniazid, ethionamide, ethambutol. In the last few years, many progresses have been made using C. glutamicum as a model microorganism, because, in contrast to mycobacteria we and others showed that viable mutants totally or severely deprived of mycolates or synthesizing a truncated AG could be obtained. Despite the fact that a large part of the cytoplasmic steps of these biosynthetic pathways has been elucidated, only little information is available regarding the trafficking of these cell wall components across the whole cell envelope and their final assembly to yield this very complex and fascinating architecture.

Currently, our group is focused on different projects using C. glutamicum and M. smegmatis as model organisms:

  • Structure and function of Mycoloyltransferases and their role during cell elongation and division
  • Protein mycoloylation: an atypical post translationnal modification

team

Nicolas BAYAN

Group Leader

Professor

Christophe REGEARD

Associate Professor

Florence CONSTANTINESCO-BECKER

Associate Professor

CécileLABARRE

Associate Professor

Christine HOUSSIN

Associate Professor

Postdoc

Célia DE SOUSA-D'AURIA

Engineer

Christiane DIETRICH

Assistant Engineer

Maya BEDOISEAU

Master Intern

Yijie ZHANG

PhD student

Tianyue WEI

PhD student

Théo CHADES

PhD student

Lucas MENAIS

PhD student

Latest publications

For all the publications of the Team click on the button below.

External funding

ANR PhoCellDiv 2018-2022

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