title: Telomere associated primase Tap repairs truncated telomeres of Streptomyces.
abstract: Replication of the linear chromosomes of soil bacteria Streptomyces proceeds from an internal origin towards the telomeres, followed by patching of the resulting terminal single-strand overhangs by DNA synthesis using terminal proteins as the primer, which remains covalently bound to the 5΄ ends of the DNA. In most Streptomyces chromosomes, the end patching requires the single-strand overhangs, terminal protein Tpg, and terminal associated protein Tap. The telomere overhangs contain several palindromic sequences capable of forming stable hairpins. Previous in vitro deoxynucleotidylation studies indicated that Tap adds the Palindrome I sequence to Tpg, which is extended by a polymerase to fill the gap. In this study, the stringency of Palindrome I sequence was examined by an in vitro deoxynucleotidylation system and in vivo replication. Several nt in Palindrome I were identified to be critical for priming. While the first 3 G on the template were required for deoxynucleotidylation in vitro, deletions of them could be suppressed by the presence of dGTP. In vivo, deletions of these G were also tolerated, and the telomere sequence was restored in the linear plasmid DNA. Our results indicated that the truncated telomeres were repaired by extension synthesis by Tap on the foldback Palindrome I sequence.
authors.affiliation: Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan.
authors.forename: Chien-Chin
authors.initials: CC
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Chung-Yuan Christian University, Chung-li, Taiwan.
authors.forename: Shu-Min
authors.initials: SM
authors.lastname: Tseng
authors.affiliation: Institute of Biochemical and Biomedical Engineering, National Taipei University of Technology, Taipei, Taiwan.
authors.forename: Hung-Yin
authors.initials: HY
authors.lastname: Pan
authors.affiliation: Institute of Biochemical and Biomedical Engineering, National Taipei University of Technology, Taipei, Taiwan.
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Huang
authors.affiliation: Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Carton W
authors.initials: CW
authors.lastname: Chen
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D020029:Base Pairing; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000737:chemistry; D019915:DNA Primase / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000235:genetics* / Q000378:metabolism; D048170:Streptomyces lividans / Q000235:genetics* / Q000378:metabolism; D016615:Telomere / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D019915:DNA Primase