Structure of cryptic lambda prophages.
Structure of cryptic lambda prophages.
复制标题
神秘的 lambda 原噬菌体的结构。
DOI：
10.1016/0022-2836(87)90289-0
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发表时间：
1987
影响因子：
5.6
通讯作者：
Campbell,AM
中科院分区：
文献类型：
--
作者：
Redfield,RJ;Campbell,AM
当大肠杆菌细胞溶原性λ噬菌体诱导紫外线，携带隐蔽λ噬菌体的细胞中偶尔发现明显治愈的幸存者。λ变体隐原（λcrg）携带转座因子IS 2的插入，其将隐溶原的频率增加到约50%的治愈细胞：这些隐原噬菌体中的43个已被表征。它们都含有用宿主染色体的一个大片段的重复拷贝替换原噬菌体基因组的早期片段（从IS 2到靠近cos位点）的替换。在大肠杆菌中，12.5分钟时，原噬菌体的nin-QSR-cos区域与同源的不完全拟马氏链原噬菌体Qsr′之间发生重组，从而导致右端的取代。coli染色体。置换的左端通常是一个交换，它将原噬菌体中的IS 2元件与E.在8.5分钟时与位于lac基因附近的第二个IS 2，或在2分钟时与位于leu逆时针方向的第二个IS 2，产生至少200，000个碱基的重复。已对来源于λ参考菌株（缺乏λcrg中存在的IS 2）溶原性细胞的5种隐蔽溶原菌进行了表征。它们含有通过与Qsr′原噬菌体交换而产生的右端替换。这些取代的左端是由λ exo基因和Qsr′的一个短的外同源片段之间的交叉形成的（2 5），或者是由attL左侧序列和宿主染色体的一个未定位的远距离区域之间的交叉形成的（3 5）。与串联复制不同，这些隐蔽溶原携带的大复制是稳定的，因此可能会显著影响细胞的进化潜力。
When Escherichia coli cells lysogenic for bacteriophage λ are induced with ultraviolet light, cells carrying cryptic λ prophages are occasionally found among the apparently cured survivors. The λ variant crypticogen (λcrg) carries an insertion of the transposable element IS2, which increases the frequency of cryptic lysogens to about 50% of cured cells: 43 of these cryptic prophages have been characterized. They all contain substitutions that replace the early segment of the prophage genome (from the IS2 to near the cos site) with a duplicate copy of a large segment of the host chromosome. The right end of the substitution always results from recombination between the nin-QSR-cos region of the prophage and the homologous incomplete lambdoid prophage Qsr′ at 12.5 minutes in the E. coli chromosome. The left end of the substitution is usually a crossover that recombines the IS2 element in the prophage with an E. coli IS2 at 8.5 minutes, near the lac gene, or with a second IS2 located counterclockwise from leu at 2 minutes, generating duplications of at least 200,000 bases. Five cryptic lysogens derived from cells lysogenic for a reference strain of λ (which lacks the IS2 present in λcrg) have been characterized. They contain substitutions whose right termini are generated by a crossover with the Qsr′ prophage. The left termini of these substitutions are formed either by a crossover between the λ exo gene and a short exo-homologous segment of Qsr′(2 5), or by a crossover between sequences to the left of attL and an unmapped distant region of the host chromosome (3 5). The large duplications carried by these cryptic lysogens are stable, unlike tandem duplications, and so may significantly influence the cell's evolutionary potential.