Document Detail

Characterization of a Vibrio fischeri aminopeptidase and evidence for its influence on an early stage of squid colonization.
MedLine Citation:
PMID:  22636772     Owner:  NLM     Status:  MEDLINE    
Vibrio fischeri cells are the sole colonists of a specialized light organ in the mantle cavity of the sepiolid squid Euprymna scolopes. The process begins when the bacteria aggregate in mucus secretions outside the light organ. The cells eventually leave the aggregate, enter the light organ, and encounter a rich supply of peptides. The need to dissociate from mucus and presumably utilize peptides led us to hypothesize that protease activity is integral to the colonization process. Protease activity associated with whole cells of Vibrio fischeri strain ES114 was identified as the product of a putative cell membrane-associated aminopeptidase (PepN). To characterize this activity, the aminopeptidase was cloned, overexpressed, and purified. Initial steady-state kinetic studies revealed that the aminopeptidase has broad activity, with a preference for basic and hydrophobic side chains and k(cat) and K(m) values that are lower and smaller, respectively, than those of Escherichia coli PepN. A V. fischeri mutant unable to produce PepN is significantly delayed in its ability to colonize squid within the first 12 h, but eventually it establishes a wild-type colonization level. Likewise, in competition with the wild type for colonization, the mutant is outcompeted at 12 h postinoculation but then competes evenly by 24 h. Also, the PepN-deficient strain fails to achieve wild-type levels of cells in aggregates, suggesting an explanation for the initial colonization delay. This study provides a foundation for more studies on PepN expression, localization, and role in the early stages of squid colonization.
Pat M Fidopiastis; Bethany A Rader; David G Gerling; Nestor A Gutierrez; Katherine H Watkins; Michelle West Frey; Spencer V Nyholm; Cheryl A Whistler
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2012-05-25
Journal Detail:
Title:  Journal of bacteriology     Volume:  194     ISSN:  1098-5530     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-07-20     Completed Date:  2012-10-02     Revised Date:  2013-08-15    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3995-4002     Citation Subset:  IM    
Biological Sciences Department, California Polytechnic University, San Luis Obispo, California, USA.
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MeSH Terms
Aliivibrio fischeri / enzymology*,  growth & development,  physiology*
Amino Acid Sequence
Aminopeptidases / genetics,  metabolism*
Animal Structures / microbiology
Cloning, Molecular
Decapodiformes / microbiology*
Escherichia coli / genetics
Gene Expression
Molecular Sequence Data
Recombinant Proteins / genetics,  isolation & purification,  metabolism
Sequence Homology, Amino Acid
Substrate Specificity
Reg. No./Substance:
0/Recombinant Proteins; EC 3.4.11.-/Aminopeptidases
Erratum In:
J Bacteriol. 2013 Jul;195(14):3298

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