title: Translesion-synthesis DNA polymerases participate in replication of the telomeres in Streptomyces.
abstract: Linear chromosomes and linear plasmids of Streptomyces are capped by terminal proteins that are covalently bound to the 5'-ends of DNA. Replication is initiated from an internal origin, which leaves single-stranded gaps at the 3'-ends. These gaps are patched by terminal protein-primed DNA synthesis. Streptomyces contain five DNA polymerases: one DNA polymerase I (Pol I), two DNA polymerases III (Pol III) and two DNA polymerases IV (Pol IV). Of these, one Pol III, DnaE1, is essential for replication, and Pol I is not required for end patching. In this study, we found the two Pol IVs (DinB1 and DinB2) to be involved in end patching. dinB1 and dinB2 could not be co-deleted from wild-type strains containing a linear chromosome, but could be co-deleted from mutant strains containing a circular chromosome. The resulting ΔdinB1 ΔdinB2 mutants supported replication of circular but not linear plasmids, and exhibited increased ultraviolet sensitivity and ultraviolet-induced mutagenesis. In contrast, the second Pol III, DnaE2, was not required for replication, end patching, or ultraviolet resistance and mutagenesis. All five polymerase genes are relatively syntenous in the Streptomyces chromosomes, including a 4-bp overlap between dnaE2 and dinB2. Phylogenetic analysis showed that the dinB1-dinB2 duplication occurred in a common actinobacterial ancestor.
authors: Department of Life Sciences and Institute of Genome Sciences, Institute of Biotechnology in Medicine, National Yang-Ming University, Shih-Pai, Taipei 11221, Taiwan.
authors: Hsiu-Hui
authors: HH
authors: Tsai
authors: Hung-Wei
authors: HW
authors: Shu
authors: Chien-Chin
authors: CC
authors: Yang
authors: Carton W
authors: CW
authors: Chen
mesh_terms: D039903:Actinobacteria / Q000235:genetics; D000478:Alkylation; D002876:Chromosomes, Bacterial / Q000737:chemistry; D003227:Conjugation, Genetic; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004258:DNA Polymerase III / Q000145:classification / Q000235:genetics / Q000502:physiology*; D019951:DNA Polymerase beta / Q000145:classification / Q000235:genetics / Q000502:physiology*; D004260:DNA Repair; D004261:DNA Replication; D017353:Gene Deletion; D020440:Gene Duplication; D022761:Gene Transfer, Horizontal; D010802:Phylogeny; D010957:Plasmids / Q000096:biosynthesis; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics*; D026801:Synteny; D016615:Telomere / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D004247:DNA; D004258:DNA Polymerase III; D019951:DNA Polymerase beta