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A conserved anti‐repressor controls horizontal gene transfer by proteolysis
Author(s) -
Bose Baundauna,
Auchtung Jennifer M.,
Lee Catherine A.,
Grossman Alan D.
Publication year - 2008
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.1365-2958.2008.06414.x
Subject(s) - repressor , biology , bacillus subtilis , genetics , gene , mutant , horizontal gene transfer , microbiology and biotechnology , gene expression , bacteria , phylogenetics
Summary The mobile genetic element ICE Bs1 is an integrative and conjugative element (a conjugative transposon) found in the Bacillus subtilis chromosome. The SOS response and the RapI‐PhrI sensory system activate ICE Bs1 gene expression, excision and transfer by inactivating the ICE Bs1 repressor protein ImmR. Although ImmR is similar to many characterized phage repressors, we found that, unlike these repressors, inactivation of ImmR requires an ICE Bs1 ‐encoded anti‐repressor ImmA (YdcM). ImmA was needed for the degradation of ImmR in B. subtilis . Coexpression of ImmA and ImmR in Escherichia coli or co‐incubation of purified ImmA and ImmR resulted in site‐specific cleavage of ImmR. Homologues of immR and immA are found in many mobile genetic elements. We found that the ImmA homologue encoded by B. subtilis phage φ105 is required for inactivation of the φ105 repressor (an ImmR homologue). ImmA‐dependent proteolysis of ImmR repressors may be a conserved mechanism for regulating horizontal gene transfer.