Structural features of λ site-specific recombination at a secondary att site in galT
Structural features of λ site-specific recombination at a secondary att site in galT
复制标题
galT 次级 att 位点 λ 位点特异性重组的结构特征
DOI：
10.1016/0092-8674(79)90015-1
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发表时间：
1979
期刊：
影响因子：
64.5
通讯作者：
A. Landy
中科院分区：
文献类型：
--
作者：
K. Bidwell;A. Landy
噬菌体 X DNA 整合到大肠杆菌宿主的染色体中是通过噬菌体和细菌染色体上特定基因座（att 位点）之间的位点特异性重组进行的。删除主要细菌尾部位点的大肠杆菌宿主的感染会导致散布在大肠杆菌染色体周围的许多不同“次要尾部位点”的 X 整合效率降低。本文报道了对 galT 基因中出现的此类次级尾部位点的首次 DNA 序列分析，并讨论了与 M 依赖性位点特异性重组机制相关的几个特征。先前的研究表明，M依赖性重组中的交叉必须位于噬菌体和初级细菌att位点以及位于原噬菌体和宿主DNA连接处的左右原噬菌体尾部位点共有的15 bp序列（核心区域）内的某个位置。 ga/T次级前噬菌体尾部位点与初级前噬菌体尾部位点的比较允许确定ga/T次级后部位点中的类似“核心”区域。由此鉴定的 15 bp 序列显示与野生型核心的中断同源性（15 个中的 8 个）。非同源碱基的范围和排列允许将这种重组的交叉点精确地放置在核心区的+ 4-+ 5核苷酸间键上。核心区侧翼的序列与噬菌体或初级细菌亲和位点的类似序列没有显示出明显的同源性。 ga/T 左原噬菌体尾部位点与类似野生型位点的比较特别令人感兴趣，并在与纯化 int 蛋白的结合研究中进行讨论。
Integration of bacteriophage X DNA into the chromosome of its E. coli host proceeds via a sitespecific recombination between specific loci (att sites) on the phage and bacterial chromosomes. Infection of an E. coli host deleted for the primary bacterial aft site results in X integration with reduced efficiency at a number of different “secondary aft sites” scattered around the E. coli chromosome. The first DNA sequence analysis of such a secondary aft site, that occurring in the galT gene, is reported here, and several features pertinent to the mechanism of M-dependent sitespecific recombination are discussed. Previous studies have shown that the crossover in M-dependent recombination must be somewhere within a 15 bp sequence(core region) common to the phage and primary bacterial att sites, as well as to the left and right prophage aft sites which are at the junctures between prophage and host DNA. Comparison of the ga/T secondary prophage aft sites with the primary prophage aft sites allows determination of the analogous“core” region in the ga/T secondary aft site. The 15 bp sequence thus identified shows an interrupted homology(8 out of 15) with the wild-type core. The extent and arrangement of nonhomologous bases allow precise placement of the crossover point for this recombination to the+ 4-+ 5 internucleotide bond of the core region.Sequences flanking the core region show no obvious homology with analogous sequences of the phage or primary bacterial aff sites. Comparison of the ga/T left prophage aft site with the analogous wild-type site is of particular interest and is discussed in relation to binding studies with purified int protein.