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Identifying regulators of transcription in an obligate intracellular pathogen: a metal‐dependent repressor in Chlamydia trachomatis
Author(s) -
Wyllie Susan,
Raulston Jane E.
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02453.x
Subject(s) - biology , orfs , repressor , chlamydia trachomatis , open reading frame , escherichia coli , genetics , gene , regulon , promoter , transcription (linguistics) , peptide sequence , transcription factor , gene expression , virology , linguistics , philosophy
A prominent feature exhibited by Chlamydia trachomatis growing in an iron‐limiting environment is a differential pattern of protein expression. In many bacteria, iron‐responsive proteins are regulated at the level of transcription by a family of repressors resembling the Escherichia coli ferric uptake regulator (Fur) protein. Although the chlamydial genome sequencing project did not unveil an obvious Fur homologue, a detailed examination indicated five unassigned open reading frames (ORFs) that would encode products with limited sequence homology to Fur. In this report, each chlamydial ORF was engineered in E. coli , and recombinant proteins were examined for functional characteristics resembling Fur. A Fur‐specific polyclonal antiserum revealed that the protein encoded by ORF CT296 shares antigenic cross‐recognition. Moreover, this protein forms dimers in solution in a fashion analogous to E. coli Fur. Further studies confirmed that the product of ORF CT296 is able to (i) complement Fur activity in a mutant strain of E. coli; and (ii) specifically bind to a 19 bp consensus sequence found in promoters of iron‐regulated genes in E. coli . We propose a designation of dcrA ( d ivalent c ation‐dependent r egulator A) for ORF CT296, which encodes a protein distantly related to E. coli Fur. DcrA represents the first repressor described for this obligate intracellular bacterium.