枯草芽孢杆菌DNA聚合酶III的tau亚基与噬菌体SPP1复制性DNA解旋酶G40P相互作用。
Bacillus subtilis tau subunit of DNA polymerase III interacts with bacteriophage SPP1 replicative DNA helicase G40P.
作者信息
Martínez-Jiménez María I, Mesa Pablo, Alonso Juan C
机构信息
Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, C.S.I.C., Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
出版信息
Nucleic Acids Res. 2002 Dec 1;30(23):5056-64. doi: 10.1093/nar/gkf650.
Genetic evidence suggests that the Bacillus subtilis dnaX gene only encodes for the tau subunit of both DNA polymerases III (Pol IIIs). The B.subtilis full-length protein and their mutant derivatives tau(373- 563) (lacking the N-terminal, domains I-III or amino acid residues 1-372) and tau(1-372) (lacking the C-terminal region or amino acids 373-563) have been purified. The tau protein forms tetramers, tau(373- 563) forms dimers, whereas tau(1-372), depending on the ionic strength, forms trimers or tetramers in solution. In the absence of single-stranded (ss) DNA and a nucleotide cofactor, tau interacts with the SPP1 hexameric replicative G40P DNA helicase in solution or with G40P-ATP bound to ssDNA, with a 1:1 stoichiometry. G40P(109-442), lacking the N-terminal amino acid residues 1-108, interacts with the C-terminal moiety of tau. The data indicate that the interaction of G40P with the tau subunit of Pol III, is relevant for the loading of the Pol IIIs into the SPP1 G38P-promoted open complex.
遗传证据表明，枯草芽孢杆菌的dnaX基因仅编码DNA聚合酶III（Pol IIIs）的τ亚基。已纯化出枯草芽孢杆菌全长蛋白及其突变衍生物τ(373 - 563)（缺少N端结构域I - III或氨基酸残基1 - 372）和τ(1 - 372)（缺少C端区域或氨基酸373 - 563）。τ蛋白形成四聚体，τ(373 - 563)形成二聚体，而τ(1 - 372)根据离子强度在溶液中形成三聚体或四聚体。在没有单链（ss）DNA和核苷酸辅因子的情况下，τ在溶液中与SPP1六聚体复制型G40P DNA解旋酶相互作用，或与结合到ssDNA上的G40P - ATP以1:1的化学计量比相互作用。缺少N端氨基酸残基1 - 108的G40P(109 - 442)与τ的C端部分相互作用。数据表明，G40P与Pol III的τ亚基的相互作用与将Pol IIIs加载到SPP1 G38P促进的开放复合物中有关。
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