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Identification and function of the RNA chaperone Hfq in the Lyme disease spirochete Borrelia burgdorferi
Author(s) -
Lybecker Meghan C.,
Abel Cassandra A.,
Feig Andrew L.,
Samuels D. Scott
Publication year - 2010
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.1365-2958.2010.07374.x
Subject(s) - rpos , borrelia burgdorferi , biology , mutant , spirochaetaceae , microbiology and biotechnology , gene , sigma factor , escherichia coli , gene expression , genetics , rna polymerase , antibody , promoter
Summary Hfq is a global regulatory RNA‐binding protein. We have identified and characterized an atypical Hfq required for gene regulation and infectivity in the Lyme disease spirochete Borrelia burgdorferi . Sequence analyses of the putative B. burgdorferi Hfq protein revealed only a modest level of similarity with the Hfq from Escherichia coli , although a few key residues are retained and the predicted tertiary structure is similar. Several lines of evidence suggest that the B. burgdorferi bb0268 gene encodes a functional Hfq homologue. First, the hfq Bb gene ( bb0268 ) restores the efficient translation of an rpoS :: lacZ fusion in an E. coli hfq null mutant. Second, the Hfq from B. burgdorferi binds to the small RNA DsrA Bb and the rpoS mRNA. Third, a B. burgdorferi hfq null mutant was generated and has a pleiotropic phenotype that includes increased cell length and decreased growth rate, as found in hfq mutants in other bacteria. The hfq Bb mutant phenotype is complemented in trans with the hfq gene from either B. burgdorferi or, surprisingly, E. coli . This is the first example of a heterologous bacterial gene complementing a B. burgdorferi mutant. The alternative sigma factor RpoS and the outer membrane lipoprotein OspC, which are induced by increased temperature and required for mammalian infection, are not upregulated in the hfq mutant. Consequently, the hfq mutant is not infectious by needle inoculation in the murine model. These data suggest that Hfq plays a key role in the regulation of pathogenicity factors in B. burgdorferi and we hypothesize that the spirochete has a complex Hfq‐dependent sRNA network.