The CHAP domain of Cse functions as an endopeptidase that acts at mature septa to promote Streptococcus thermophilus cell separation
Résumé
Cell separation is dependent on cell wall hydrolases that cleave the peptidoglycan shared between daughter cells. In Streptococcus thermophilus, this step is performed by the Cse protein whose depletion resulted in the formation of extremely long chains of cells. Cse, a natural chimeric enzyme created by domain shuffling, carries at least two important domains for its activity: the LysM expected to be responsible for the cell wall-binding and the CHAP domain predicted to contain the active centre. Accordingly, the localization of Cse on S. thermophilus cell surface has been undertaken by immunogold electron and immunofluorescence microscopies using of antibodies raised against the N-terminal end of this protein. Immunolocalization shows the presence of the Cse protein at mature septa. Moreover, the CHAP domain of Cse exhibits a cell wall lytic activity in zymograms performed with cell walls of Micrococcus lysodeikticus, Bacillus sub-tilis and S. thermophilus. Additionally, RP-HPLC analysis of muropeptides released from B. subtilis and S. thermophilus cell wall after digestion with the CHAP domain shows that Cse is an endopeptidase. Altogether, these results suggest that Cse is a cell wall hydrolase involved in daughter cell separation of S. thermophilus.
Mots clés
CHAP domain
Valérie
ecophysiology and functional ecology Legué
Bacterial Biochemistry Borges
Nancy University
Nathalie
Pascal
Bacterial Biochemistry Courtin
Genetic and Microbiology Gérard
cell separation
mature septa
Frédéric
Séverine
Complete List of Authors: Layec
Joelle
LSGA Decaris
ENSAIA
Bernard
Genetic and Microbiology Key Words: peptidoglycan hydrolase
INRA
Genetic and Microbiology Leblond-Bourget
ecophysiology and functional ecology Chapot-Chartier
Genomic
Streptococcus thermophilus
Marie-Pierre
Origine | Fichiers produits par l'(les) auteur(s) |
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