AdnAB: A new DSB-resecting motor-nuclease from mycobacteria Journal Article
| Authors: | Sinha, K. M.; Unciuleac, M. C.; Glickman, M. S.; Shuman, S. |
| Article Title: | AdnAB: A new DSB-resecting motor-nuclease from mycobacteria |
| Abstract: | The resection of DNA double-strand breaks (DSBs) in bacteria is a motor-driven process performed by a multisubunit helicase-nuclease complex: either an Escherichia coli-type RecBCD enzyme or a Bacillus-type AddAB enzyme. Here we identify mycobacterial AdnAB as the founder of a new family of heterodimeric helicase-nucleases with distinctive properties. The AdnA and AdnB subunits are each composed of an N-terminal UvrD-like motor domain and a C-terminal nuclease module. The AdnAB ATPase is triggered by dsDNA with free ends and the energy of ATP hydrolysis is coupled to DSB end resection by the AdnAB nuclease. The mycobacterial nonhomologous end-joining (NHEJ) protein Ku protects DSBs from resection by AdnAB. We find that AdnAB incises ssDNA by measuring the distance from the free 5′ end to dictate the sites of cleavage, which are predominantly 5 or 6 nucleotides (nt) from the 5′ end. The "molecular ruler" of AdnAB is regulated by ATP, which elicits an increase in ssDNA cleavage rate and a distal displacement of the cleavage sites 16-17 nt from the 5′ terminus. AdnAB is a dual nuclease with a clear division of labor between the subunits. Mutations in the nuclease active site of the AdnB subunit ablate the ATP-inducible cleavages; the corresponding changes in AdnA abolish ATP-independent cleavage. Complete suppression of DSB end resection requires simultaneous mutation of both subunit nucleases. The nuclease-null AdnAB is a helicase that unwinds linear plasmid DNA-without degrading the displaced single strands. Mutations of the phosphohydrolase active site of the AdnB subunit ablate DNA-dependent ATPase activity, DSB end resection, and ATP-inducible ssDNA cleavage; the equivalent mutations of the AdnA subunit have comparatively little effect. AdnAB is a novel signature of the Actinomycetales taxon. Mycobacteria are exceptional in that they encode both AdnAB and RecBCD, suggesting the existence of alternative end-resecting motor-nuclease complexes. © 2009 by Cold Spring Harbor Laboratory Press. |
| Keywords: | unclassified drug; genetics; mutation; nonhuman; metabolism; dna repair; carboxy terminal sequence; enzymology; physiology; chemistry; amino terminal sequence; escherichia coli; dna breaks, double-stranded; nuclease; double stranded dna break; models, molecular; protein structure, tertiary; chemical structure; helicase; adenosine triphosphate; single stranded dna; ku antigen; multienzyme complex; multienzyme complexes; adenosine triphosphatase; bacterial dna; mycobacterium; corynebacterineae; protein tertiary structure; dna, bacterial; dna cleavage; atp-dependent nuclease; double-strand breaks; molecular ruler; plasmid dna; protein adna; protein adnab; protein adnb; deoxyribonuclease; dna dependent atpase endonuclease; dna-dependent atpase-endonuclease; exodeoxyribonuclease; actinomycetales; endodeoxyribonucleases; exodeoxyribonucleases |
| Journal Title: | Genes and Development |
| Volume: | 23 |
| Issue: | 12 |
| ISSN: | 0890-9369 |
| Publisher: | Cold Spring Harbor Laboratory Press |
| Date Published: | 2009-06-15 |
| Start Page: | 1423 |
| End Page: | 1437 |
| Language: | English |
| DOI: | 10.1101/gad.1805709 |
| PUBMED: | 19470566 |
| PROVIDER: | scopus |
| PMCID: | PMC2701575 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 8" - "Export Date: 30 November 2010" - "CODEN: GEDEE" - "Source: Scopus" |
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