The role of aminopeptidase PepS in the growth of Streptococcus thermophilus is not restricted to nitrogen nutrition.
OBJECTIVE
To investigate the effect of an absence of aminopeptidase PepS on the growth of Streptococcus thermophilus on different media and at different temperatures.


RESULTS
Using gene interruption, a negative mutant of the Strep. thermophilus CNRZ385 strain was constructed for the aminopeptidase PepS (strain DeltapepS). Checks were first of all made using biochemical assays that the DeltapepS strain lacks the peptide hydrolase activity of aminopeptidase PepS. It was demonstrated that the absence of the aminopeptidase PepS exerted a negative effect on growth whatever the culture medium (M17, chemically defined medium, milk). The role of aminopeptidase PepS in growth was enhanced at a high temperature (45 degrees C vs 37 degrees C). The DeltapepS strain was more resistant to lysozyme than the wild-type strain.


CONCLUSIONS
We were able to demonstrate that aminopeptidase PepS probably plays a pleiotropic role through its involvement in growth via nitrogen nutrition, as well as via other cellular functions/metabolisms (such as peptidoglycane metabolism).


CONCLUSIONS
This study constitutes the first report on the role of a member of the M29 MEROPS family of metallopeptidases (http://merops.sanger.ac.uk/).
Thomas
S
S
Unité de Biochimie Bactérienne, INRA, UR477, Jouy-en-Josas, France.
Besset
C
C
Courtin
P
P
Rul
F
F
D000626:Aminopeptidases / Q000378:metabolism*; D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D003470:Culture Media; D024881:Drug Resistance, Bacterial / Q000502:physiology*; D017353:Gene Deletion; D006358:Hot Temperature; D008666:Metalloendopeptidases / Q000378:metabolism*; D009113:Muramidase / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism*; D048249:Streptococcus thermophilus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*
D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D003470:Culture Media; D009113:Muramidase; D000626:Aminopeptidases; C120742:PepS protein, Streptococcus thermophilus; D008666:Metalloendopeptidases; D009584:Nitrogen