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HrpA, a DEAH‐box RNA helicase, is involved in mRNA processing of a fimbrial operon in Escherichia coli
Author(s) -
Koo Jovanka T.,
Choe Juno,
Moseley Steve L.
Publication year - 2004
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 - 10.1111/j.1365-2958.2004.04099.x
Subject(s) - biology , operon , rna helicase a , l arabinose operon , escherichia coli , helicase , rna , messenger rna , genetics , microbiology and biotechnology , gene
Summary Endonucleolytic cleavage of mRNA in the daa operon of Escherichia coli is responsible for co‐ordinate regulation of genes involved in F1845 fimbrial biogenesis. Cleavage occurs by an unidentified endoribonuclease, is translation dependent and involves a unique recognition mechanism. Here, we present the results of a genetic strategy used to identify factors involved in daa mRNA processing. We used a reporter construct consisting of the daa mRNA processing region fused to the gene encoding green fluorescent protein (GFP). A mutant defective in daa mRNA processing and expressing high levels of GFP was isolated by flow cytometry. To determine the location of mutations, two different genetic approaches, Hfr crosses and P1 transductions, were used. The mutation responsible for the processing defect was subsequently mapped to the 32 min region of the E. coli chromosome. A putative DEAH‐box RNA helicase‐encoding gene at this position, hrpA , was able to restore the ability of the mutant to cleave daa mRNA. Site‐directed mutagenesis of the hrpA regions predicted to encode nucleotide triphosphate binding and hydrolysis functions abolished the ability of the gene to restore the processing defect in the mutant. We propose that HrpA is a novel enzyme involved in mRNA processing in E. coli .