title: A Sir2-like protein participates in mycobacterial NHEJ.
abstract: In eukaryotic cells, repair of DNA double-strand breaks (DSBs) by the nonhomologous end-joining (NHEJ) pathway is critical for genome stability. In contrast to the complex eukaryotic repair system, bacterial NHEJ apparatus consists of only two proteins, Ku and a multifunctional DNA ligase (LigD), whose functional mechanism has not been fully clarified. We show here for the first time that Sir2 is involved in the mycobacterial NHEJ repair pathway. Here, using tandem affinity purification (TAP) screening, we have identified an NAD-dependent deacetylase in mycobacteria which is a homologue of the eukaryotic Sir2 protein and interacts directly with Ku. Results from an in vitro glutathione S-transferase (GST) pull-down assay suggest that Sir2 interacts directly with LigD. Plasmid-based end-joining assays revealed that the efficiency of DSB repair in a sir2 deletion mutant was reduced 2-fold. Moreover, the Δsir2 strain was about 10-fold more sensitive to ionizing radiation (IR) in the stationary phase than the wild-type. Our results suggest that Sir2 may function closely together with Ku and LigD in the nonhomologous end-joining pathway in mycobacteria.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Zhongdao
authors.initials: Z
authors.lastname: Li
authors.forename: Jikai
authors.initials: J
authors.lastname: Wen
authors.forename: Yaning
authors.initials: Y
authors.lastname: Lin
authors.forename: Shihua
authors.initials: S
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Xue
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Sui
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Bi
authors.forename: Xian-En
authors.initials: XE
authors.lastname: Zhang
mesh_terms: D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D011088:DNA Ligases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D055879:Gene Knock-In Techniques; D056426:Genetic Loci / Q000235:genetics; D007259:Infrared Rays; D000072200:Ku Autoantigen; D050296:Microbial Viability / Q000528:radiation effects; D009161:Mycobacterium / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects; D011485:Protein Binding / Q000528:radiation effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011995:Recombination, Genetic / Q000528:radiation effects; D015203:Reproducibility of Results; D037761:Sirtuins / Q000378:metabolism*
chemical_list: D034961:Antigens, Nuclear; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D037761:Sirtuins; D000072200:Ku Autoantigen; D011088:DNA Ligases