Schmitt M P, Beck P J, Kearney C A, Spence J L, DiGiovanni D, Condreay J P, Molineux I J
J Mol Biol. 1987 Feb 5;193(3):479-95. doi: 10.1016/0022-2836(87)90261-0.
The 3526 base-pair nucleotide sequence from near the end of bacteriophage T3 gene 1 to within the coding sequence of gene 2.5 is given. It includes the complete coding sequences for nine known or presumptive proteins, most of which are only conditionally essential for phage growth. The sequence includes five promoters for the phage RNA polymerase, the terminator for early (host enzyme-catalyzed) transcription, and two recognition sites for RNAase III. The primary origin of T3 DNA replication that is utilized by the phage in vivo has been localized to a 142 base-pair region. It has several features in common with the phage T7 origin of DNA replication, and exhibits considerable homology to recognition sites for the mRNA processing enzyme RNAase III. It is proposed that the primary origin of T3 DNA replication may have evolved directly from an RNAase III recognition site. The deletions present in a number of T3 mutant strains and the location of the nucleotide changes in several T3 strains that are defective in their ability to grow on F+-containing strains or on optA mutant hosts have been determined. We discuss how T3 may have become genetically isolated from its relatives in the T7-T3 group and simultaneously acquired novel biological and biochemical properties.
给出了从噬菌体T3基因1末端附近到基因2.5编码序列内的3526个碱基对的核苷酸序列。它包括9种已知或推测蛋白质的完整编码序列，其中大多数对噬菌体生长仅为条件必需。该序列包括5个噬菌体RNA聚合酶的启动子、早期（宿主酶催化）转录的终止子以及两个核糖核酸酶III的识别位点。噬菌体在体内利用的T3 DNA复制的主要起始位点已定位到一个142个碱基对的区域。它与噬菌体T7 DNA复制起始位点有几个共同特征，并且与mRNA加工酶核糖核酸酶III的识别位点表现出相当的同源性。有人提出，T3 DNA复制的主要起始位点可能直接从一个核糖核酸酶III识别位点进化而来。已经确定了一些T3突变株中的缺失以及一些在含F +菌株或optA突变宿主上生长能力有缺陷的T3菌株中核苷酸变化的位置。我们讨论了T3如何从其在T7 - T3组中的亲属中在遗传上隔离出来，同时获得新的生物学和生物化学特性。
