Document Detail


Interference of the CadC regulator in the arginine-dependent acid resistance system of Shigella and enteroinvasive E. coli.
MedLine Citation:
PMID:  19959396     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A typical pathoadaptive mutation of Shigella and enteroinvasive Escherichia coli (EIEC) is the inactivation of the cad locus which comprises the genes necessary for lysine decarboxylation, an enzyme involved in pH homoeostasis. In E. coli, the cadBA operon, encoding lysine decarboxylase (CadA) and a lysine cadaverine antiporter (CadB), is submitted to the control of CadC, a positive activator whose gene maps upstream the operon, and is transcribed independently from the same strand. CadC is an integral inner membrane protein which acts both, as signal sensor and as transcriptional regulator responding to the low pH and lysine signals. Analysis of the molecular rearrangements responsible for the loss of lysine decarboxylase activity in Shigella and EIEC has revealed that the inactivation of the cadC gene is a common feature. The 3 major adaptive acid resistance (AR) systems - AR1, AR2, and AR3 - are known to be activated at low pH by Shigella and E. coli, allowing them to withstand extremely acid conditions. In this study, evaluating the survival of S. flexneri, S. sonnei, and EIEC strains complemented with a functional cadC gene and challenged at low pH, we present evidence that CadC negatively regulates the expression of the arginine-dependent adaptive acid-resistance system (AR3), encoded by the adi locus while it has no effect on the expression of AR1 and AR2 systems. Moreover, since our results indicate that in enteroinvasive strains the presence of CadC reduces the expression of the arginine decarboxylase encoding gene adiA, it is possible to hypothesize that the loss of functionality of lysine decarboxylase is counterbalanced by a higher expression of the adi system, and that CadC, besides specifically affecting the regulation of the cadBA operon, is also relevant to other systems responding to low pH.
Authors:
Mariassunta Casalino; Gianni Prosseda; Marialuisa Barbagallo; Angelo Iacobino; Paolo Ceccarini; Maria Carmela Latella; Mauro Nicoletti; Bianca Colonna
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-12-02
Journal Detail:
Title:  International journal of medical microbiology : IJMM     Volume:  300     ISSN:  1618-0607     ISO Abbreviation:  Int. J. Med. Microbiol.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-17     Completed Date:  2010-08-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100898849     Medline TA:  Int J Med Microbiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  289-95     Citation Subset:  IM    
Copyright Information:
Copyright 2009 Elsevier GmbH. All rights reserved.
Affiliation:
Dipartimento di Biologia, Università Roma Tre, 00146 Rome, Italy.
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MeSH Terms
Descriptor/Qualifier:
Acids / toxicity*
Bacterial Proteins / genetics,  metabolism*
Base Sequence
Carboxy-Lyases / biosynthesis
Colony Count, Microbial
Down-Regulation
Escherichia coli / genetics,  physiology*
Gene Deletion
Gene Expression Regulation, Bacterial*
Genes, Reporter
Genetic Complementation Test
Microbial Viability / drug effects
Models, Biological
Molecular Sequence Data
Shigella / genetics,  physiology*
Stress, Physiological*
beta-Galactosidase / genetics,  metabolism
Chemical
Reg. No./Substance:
0/Acids; 0/Bacterial Proteins; 0/CadC protein, Bacteria; EC 3.2.1.23/beta-Galactosidase; EC 4.1.1.-/Carboxy-Lyases; EC 4.1.1.19/arginine decarboxylase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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