Chai S, Szepan U, Lüder G, Trautner T A, Alonso J C
Max-Planck-Institut für molekulare Genetik, Berlin, Germany.
Gene. 1993 Jul 15;129(1):41-9. doi: 10.1016/0378-1119(93)90694-x.
The left end of the genome of Bacillus subtilis bacteriophage SPP1 is represented by EcoRI DNA fragments 12 and 1 (EcoRI-12 and EcoRI-1). A number of different deletions were identified in EcoRI-1. A detailed physical and genetic map of EcoRI-1 from wild-type (wt) phage and SPP1 deletion mutants was constructed. Genes encoding essential products involved in late and early stages of phage DNA metabolism were mapped at the left and right ends of the 8.5-kb EcoRI-1, respectively. Deletions fell within the internal 5157-bp DNA segment of EcoRI-1. The nucleotide (nt) sequence of this region and of the endpoints of two deletions, delta X and delta L, were determined. The nt sequence of the junctions in SPP1 delta X and SPP1 delta L showed that, in these deletions, a segment of DNA between short directly repeated sequences of 10 and 13 bp, located 3427 and 4562 bp apart in the wt sequence, had been eliminated. In both cases, the copy of the repeated sequence was retained in the deletion mutant, consistent with the hypothesis that the deletions originated by homologous intramolecular recombination. The corresponding region in wt phage had fifteen presumptive open reading frames (orfs) and the previously identified SPP1 early promoters (PE1). The poor growth phenotype associated with the SPP1 deletion mutants was attributed to premature transcriptional read through from promoter(s) of the early region into late operon brought into close vicinity of the late genes due to the deletion event.
枯草芽孢杆菌噬菌体SPP1基因组的左端由EcoRI DNA片段12和1（EcoRI-12和EcoRI-1）代表。在EcoRI-1中鉴定出了许多不同的缺失。构建了野生型（wt）噬菌体和SPP1缺失突变体的EcoRI-1的详细物理和遗传图谱。参与噬菌体DNA代谢后期和早期阶段的必需产物的基因分别定位在8.5kb EcoRI-1的左端和右端。缺失位于EcoRI-1内部5157bp的DNA片段内。测定了该区域以及两个缺失（δX和δL）端点的核苷酸（nt）序列。SPP1 δX和SPP1 δL中连接处的nt序列表明，在这些缺失中，位于野生型序列中相距3427和4562bp的10和13bp短直接重复序列之间的一段DNA已被消除。在这两种情况下，重复序列的拷贝都保留在缺失突变体中，这与缺失起源于同源分子内重组的假设一致。野生型噬菌体中的相应区域有15个推定的开放阅读框（orfs）和先前鉴定的SPP1早期启动子（PE1）。与SPP1缺失突变体相关的生长不良表型归因于由于缺失事件，早期区域的启动子过早转录通读进入由于缺失而靠近晚期基因的晚期操纵子。
