Terminal, and telomere-associated proteins of pAL1, a linear plasmid from Arthrobacter nitroguajacolicus Rü61a

基于对nitroguajacolicus r<e:1> 61a新型线性质粒pAL1的序列分析，我们提出以pBD2[1]和pAL1为代表的放线菌线性质粒亚群已经进化出独特的端粒补丁机制，涉及前所未有的端粒相关蛋白（Tap）。该端粒修补系统的蛋白质可能与链霉菌线性复制子的Tap和Tpg（终端端粒结合）蛋白具有一些共同的基序，但在结构域结构方面似乎存在显著差异。推测的TappAL1含有较大的附加结构域，可能与b型DNA聚合酶有远亲关系。第一个节肢杆菌线性质粒项目的目标是鉴定所有与端粒连接并参与端粒修补的蛋白质，并表征它们的功能。我们特别感兴趣的是研究假定的TappAL1在与DNA和/或末端蛋白（TpgpAL1）相互作用中的作用，以及它在端粒修补中的潜在催化活性。主要目标是：Tpg蛋白的鉴定；鉴定（进一步）与端粒有特定亲和力的蛋白质；tpgpAL1和tappAL1的表达克隆功能研究(i)解决TpgpAL1， TappAL1（和/或其他蛋白质）DNA结合的特异性，（ii）评估TpgpAL1和TappAL1的相互作用，以及（iii）分析TappAL1是否显示脱氧核苷酸化（引物酶，聚合酶）活性。最终目标是了解端粒修补的机制。[10]张建军，张建军，张建军，等。微生物学进展[J] .微生物学杂志，2003,19(2):569 - 574。

Based on sequence analysis of the novel linear plasmid pAL1 of Arthrobacter nitroguajacolicus Rü61a, we propose that a subgroup of actinomycetal linear plasmids, represented by pBD2[1] and pAL1, have evolved a unique mechanism of telomere patching, involving an unprecedented telomere associated protein (Tap). The proteins of this telomere patching system may share some common motifs with the Tap and Tpg (terminal telomere binding) proteins of Streptomyces linear replicons, but appear to be significantly different, e.g., in their domain structure. The putative TappAL1 contains large additional domain(s) and may be distantly related to B-type DNA polymerases. The goal of this first project on an Arthrobacter linear plasmid is to identify all proteins bound to the termini and involved in telomere patching, and to characterize their function. We are especially interested in investigating the role of the presumptive TappAL1 in interacting with the DNA and/or the terminal protein(s) (TpgpAL1), and its potential catalytic activity in telomere patching. The main objectives are: Identification of the Tpg protein(s); identification of (further) proteins with specific affinity to the telomeres; expression cloning of tpgpAL1 and tappAL1; functional studies (i) addressing the specificity of DNA binding of TpgpAL1, TappAL1 (and/or other proteins), (ii) assessing the interaction of TpgpAL1 and TappAL1, and (iii) analysing whether TappAL1 shows desoxynucleotidylation (primase, polymerase) activity. The ultimate goal is to understand the mechanism of telomere patching. [1] Stecker C, Johann A, Herzberg C, Averhoff B, Gottschalk G (2003) J Bacteriol 185: 5269-5274.