A DNA damage-inducible mutagenic gene cassette has been implicated in the emergence of drug resistance in Mycobacterium tuberculosis during anti-tuberculosis (TB) chemotherapy. However, the molecular composition and operation of the encoded 'mycobacterial mutasome' - minimally comprising DnaE2 polymerase and ImuA ' and ImuB accessory proteins - remain elusive. Following exposure of mycobacteria to DNA damaging agents, we observe that DnaE2 and ImuB co-localize with the DNA polymerase III beta subunit (beta clamp) in distinct intracellular foci. Notably, genetic inactivation of the mutasome in an imuB(AAAAGG) mutant containing a disrupted beta clamp-binding motif abolishes ImuB-beta clamp focus formation, a phenotype recapitulated pharmacologically by treating bacilli with griselimycin and in biochemical assays in which this beta clamp-binding antibiotic collapses pre-formed ImuB-beta clamp complexes. These observations establish the essentiality of the ImuB-beta clamp interaction for mutagenic DNA repair in mycobacteria, identifying the mutasome as target for adjunctive therapeutics designed to protect anti-TB drugs against emerging resistance.
WOS:001077770600001
2023-08-02
12
e75628
REVIEWED
Funder | Grant Number |
Eunice Kennedy Shriver National Institute of Child Health and Human Development | U01HD085531 |
Norges Forskningsrad | 261669 |
South African Medical Research Council | |
National Research Foundation | |
Howard Hughes Medical Institute | |
Leids Universitair Medisch Centrum LUMC Fellowship | |
National Research Foundation | 104683 |
David and Elaine Potter Foundation PhD Fellowship | |