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Team's presentation

Bacteria have to adapt constantly to survive to environmental changes. Depending on nutrient availability, the gram-positive model bacterium, Bacillus subtilis, developed an arsenal of physiological strategies such as adjusting its doubling time and its size to cope with a less favorable environment. When nutrients are lacking, B. subtilis is able to incorporate exogenous DNA or to differentiate in a metabolically dormant and environmentally resistant spore to wait for better conditions. In the lab, we are studying how B. subtilis adapts to the environmental signals.

  1. We are deciphering the role of genes of unknown function for which a link with metabolism has been established, and which would regulate proteins involved in cell division or cell elongation. They can be named as metabolic sensors.
  2. In several bacteria, it was shown that Serine Threonine Protein Kinases are implicated in many bacterial processes comprising central metabolism, sporulation, cell shape. We are investigating the regulatory role of protein phosphorylation and we are studying how protein kinases regulate growth, division, morphogenesis…
  3. Bacterial small RNAs have emerged as ubiquitous post-transcriptional regulators of gene expression, able to target mRNAs with key roles in most aspects of bacterial physiology and rapid adaptative responses. We want to investigate sRNA-mediated gene regulation in the links between nutrient availability, cell cycle processes, competence and sporulation.

Team's news

Team projects

AXIS 1

Regulation of cell elongation

AXIS 2

Protein kinases and phosphorylation events.

AXIS 3

sRNA interactome dynamics along environmental changes

Bacteria must have robust mechanisms to maintain their shape and their size and pass them to their progeny. One of the actors involved in this conservative process is the cell wall that provides bacterial physical integrity by balancing the high internal turgor pressure and maintains cell morphology. The main component of this cell wall is the peptidoglycan (PG), a polymer that is continuously remodeled during growth. PG precursors are synthesized in the cytoplasm and then exported across the cytoplasmic membrane, to be incorporated into pre-existing sacculus by the action of enzymes with either synthesizing or hydrolyzing activities. Major enzymes that catalyze PG synthesis are called penicillin-binding proteins (PBPs) because they bind the cell-wall antibiotic penicillin. Hence, therapeutic interests have fueled our extensive knowledge on these enzymes. However, while the biosynthetic pathway leading from intra-cellular sugar and amino acid intermediates to PG precursors is well understood, little is known about how cells control these enzymes. Our objective is to find and study regulators of these biosynthetic enzymes in particular in the Gram-positive bacteria B. subtilis where the PG layer is very thick.

Protein phosphorylation is a post-translational modification that affects protein activity through the addition of a phosphate moiety from a molecule of ATP by protein kinases. It occurs in all life forms and is important for a wide range of cellular processes. Bacteria possess a diverse repertoire of protein kinase families. Beyond these kinase families, one of them is conserved in eukaryotes and bacteria. This is the Hanks kinases, that catalyze phosphorylation of proteins on serine and threonine residues in bacteria; they are also called Ser/Thr Protein Kinases (STPKs). In the team, we decipher the role of these STPKs and phosphorylation events in the regulation of B. subtilis cellular processes.

In response to starvation, B. subtilis is able to differentiate in a dormant spore able to survive in extreme environmental conditions. Characterizing strategies used to control division and cell shape through changing environments is one of the biggest challenges in microbiology. Small noncoding RNAs (sRNAs) have emerged as the main class of post-transcriptional regulators in bacteria. sRNA synthesis is tightly controlled; most of them are transcribed transiently usually in response to environmental variations and allows a fast adaptive response. sRNAs imperfectly base-pair to multiple target-mRNAs involved in most aspects of bacterial physiology and thereby regulate, their translation and/or stability via a multitude of mechanisms. In B. subtilis, the sRNA-based regulation network is surprisingly poorly characterized. Our project aims to bring to light the sRNA-based network in regulating cellular processes (growth rate, cell size or sporulation) depending on the nutriment availability in this bacteria chosen as a model of study.

The Team

Anne Galinier

Group leader / Research director (DR-CNRS)

Clémentine Delan Forino

Researcher (CR-CNRS)

Elodie Foulquier Khadaroo

Engineer (IE-CNRS)

Frédérique Pompeo

Researcher (CR-CNRS)

Hakima Lakhal

Engineer (CDD-CNRS)

Ao Zhang

PhD student (PhD-AMU)

Scientific publications