Details

Autor(en) / Beteiligte

• Warner, Digby F.
• Ndwandwe, Duduzile E.
• Abrahams, Garth L.
• Kana, Bavesh D.
• Machowski, Edith E.
• Venclovas, Česlovas
• Mizrahi, Valerie
• Benkovic, Stephen J.

Titel

Essential roles for imuA' - and imuB -encoded accessory factors in DnaE2-dependent mutagenesis in Mycobacterium tuberculosis

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2010-07, Vol.107 (29), p.13093-13098

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2010

Quelle

MEDLINE

Beschreibungen/Notizen

• In Mycobacterium tuberculosis (Mtb), damage-induced mutagenesis is dependent on the C-family DNA polymerase, DnaE2. Included with dnaE2 in the Mtb SOS regulon is a putative operon comprising Rv3395c, which encodes a protein of unknown function restricted primarily to actinomycetes, and Rv3394c, which is predicted to encode a Y-family DNA polymerase. These genes were previously identified as components of an imuA-imuB-dnaE2–type mutagenic cassette widespread among bacterial genomes. Here, we confirm that Rv3395c (designated imuA') and Rv3394c (imuB) are individually essential for induced mutagenesis and damage tolerance. Yeast two-hybrid analyses indicate that ImuB interacts with both ImuA' and DnaE2, as well as with the β-clamp. Moreover, disruption of the ImuB-β clamp interaction significantly reduces induced mutagenesis and damage tolerance, phenocopying imuA', imuB, and dnaE2 gene deletion mutants. Despite retaining structural features characteristic of Y-family members, ImuB homologs lack conserved active-site amino acids required for polymerase activity. In contrast, replacement of DnaE2 catalytic residues reproduces the dnaE2 gene deletion phenotype, strongly implying a direct role for the α-subunit in mutagenic lesion bypass. These data implicate differential protein interactions in specialist polymerase function and identify the split imuA'-imuB/dnaE2 cassette as a compelling target for compounds designed to limit mutagenesis in a pathogen increasingly associated with drug resistance.