Mycobacterial helicase Lhr abets resistance to DNA crosslinking agents mitomycin C and cisplatin Journal Article
| Authors: | Warren, G. M.; Ejaz, A.; Fay, A.; Glickman, M. S.; Shuman, S. |
| Article Title: | Mycobacterial helicase Lhr abets resistance to DNA crosslinking agents mitomycin C and cisplatin |
| Abstract: | Mycobacterium smegmatis Lhr exemplifies a novel clade of helicases composed of an N-terminal ATPase/helicase domain (Lhr-Core) and a large C-terminal domain (Lhr-CTD) that nucleates a unique homo-tetrameric quaternary structure. Expression of Lhr, and its operonic neighbor Nei2, is induced in mycobacteria exposed to mitomycin C (MMC). Here we report that lhr deletion sensitizes M. smegmatis to killing by DNA crosslinkers MMC and cisplatin but not to killing by monoadduct-forming alkylating agent methyl methanesulfonate or UV irradiation. Testing complementation of MMC and cisplatin sensitivity by expression of Lhr mutants in Δlhr cells established that: (i) Lhr-CTD is essential for DNA repair activity, such that Lhr-Core does not suffice; (ii) ATPase-defective mutant D170A/E171A fails to complement; (iii) ATPase-active, helicase-defective mutant W597A fails to complement and (iv) alanine mutations at the CTD-CTD interface that interdict homo-tetramer formation result in failure to complement. Our results instate Lhr's ATP-driven motor as an agent of inter-strand crosslink repair in vivo, contingent on Lhr's tetrameric quaternary structure. We characterize M. smegmatis Nei2 as a monomeric enzyme with AP β-lyase activity on single-stranded DNA. Counter to previous reports, we find Nei2 is inactive as a lyase at a THF abasic site and has feeble uracil glycosylase activity. © The Author(s) 2023. Published by Oxford University Press on behalf of Nucleic Acids Research. |
| Keywords: | genetics; cisplatin; metabolism; dna repair; bacterial protein; bacterial proteins; single stranded dna; dna, single-stranded; mitomycin; adenosine triphosphatase; mycobacterium; adenosine triphosphatases; dna helicases; dna helicase |
| Journal Title: | Nucleic Acids Research |
| Volume: | 51 |
| Issue: | 1 |
| ISSN: | 0305-1048 |
| Publisher: | Oxford University Press |
| Date Published: | 2023-01-11 |
| Start Page: | 218 |
| End Page: | 235 |
| Language: | English |
| DOI: | 10.1093/nar/gkac1222 |
| PUBMED: | 36610794 |
| PROVIDER: | scopus |
| PMCID: | PMC9841417 |
| DOI/URL: | |
| Notes: | Article -- MSK corresponding author is Stewart Shuman -- Export Date: 1 February 2023 -- Source: Scopus |
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