Document Detail


Identification of an l-alanine export system in Escherichia coli and isolation and characterization of export-deficient mutants.
MedLine Citation:
PMID:  21208269     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
An Escherichia coli strain that exhibits a double auxotrophy for l-alanine and d-alanine was constructed. During growth in the presence of the dipeptide l-alanyl-l-alanine (Ala-Ala), this was fully consumed with concomitant extracellular accumulation of l-alanine in a twofold molar concentration compared with the dipeptide. This finding indicates that the strain not only can hardly degrade l-alanine but has an export system(s) for l-alanine. To obtain access to the system, we chemically mutagenized the l-alanine-nonmetabolizing strain and isolated mutants with increased Ala-Ala sensitivity. Two such mutants accumulated l-alanine up to 150-190 mM in the cytoplasm with a reduced rate of l-alanine export relative to the parent strain in the presence of Ala-Ala. Furthermore, when chloramphenicol was added together with Ala-Ala, the parent strain accumulated l-alanine in the cytoplasm to a level similar to that observed in the mutants in the absence of chloramphenicol. In contrast, the intracellular l-alanine level in the mutants did not change irrespective of chloramphenicol treatment. From these results, we conclude that E. coli has an inducible l-alanine export carrier, together with a second, as yet unidentified, mechanism of alanine export.
Authors:
Hatsuhiro Hori; Tasuke Ando; Emiko Isogai; Hiroshi Yoneyama; Ryoichi Katsumata
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-1-5
Journal Detail:
Title:  FEMS microbiology letters     Volume:  -     ISSN:  1574-6968     ISO Abbreviation:  -     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-1-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7705721     Medline TA:  FEMS Microbiol Lett     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Affiliation:
Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, Japan.
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