Nilssen O, Six E W, Sunshine M G, Lindqvist B H
Laboratory of Microbial Gene Technology, NLVF, Norway.
Virology. 1996 May 15;219(2):432-42. doi: 10.1006/viro.1996.0269.
Satellite phage P4 (11,624 bp) depends on the morphopoietic genes (capsid, tail) and lysis genes of its helper phage P2 (33.5 kb) for its lytic development. In the morphopoietic process, P4 redirects the assembly pathway of large, P2 size, capsids (diameter = 60 nm) to yield smaller, P4 size, capsids (diameter = 45 nm), 1/3 in volume of that of its helper. The P4-specified capsid size determination is dependent on the function of the 27-kDa gpSid. To study the capsid size-determining function, we carried out a mutational analysis of the P4 sid gene. Use of a P4-derived genome of 29.1 kb (P461), which can be packaged only into large, P2 size, capsids allowed us to select P4 Sid- mutants. By DNA sequencing we characterized 25 P4 Sid- mutants, of which 10 contain base pair substitutions and 15 contain deletions. Both types of mutations are clustered in separate locations within the sid gene. Our results suggest that the Sid polypeptide contains three distinct functional domains.
卫星噬菌体P4（11,624碱基对）的裂解发育依赖于其辅助噬菌体P2（33.5千碱基对）的形态发生基因（衣壳、尾部）和裂解基因。在形态发生过程中，P4将大的、P2大小的衣壳（直径 = 60纳米）的组装途径重定向，以产生较小的、P4大小的衣壳（直径 = 45纳米），其体积为其辅助噬菌体衣壳体积的1/3。P4指定的衣壳大小决定取决于27千道尔顿的gpSid的功能。为了研究衣壳大小决定功能，我们对P4 sid基因进行了突变分析。使用仅能包装成大的、P2大小衣壳的29.1千碱基对的P4衍生基因组（P461），使我们能够筛选P4 Sid-突变体。通过DNA测序，我们鉴定了25个P4 Sid-突变体，其中10个含有碱基对替换，15个含有缺失。这两种类型的突变都聚集在sid基因内的不同位置。我们的结果表明，Sid多肽包含三个不同的功能结构域。
