Schaefer T S, Hays J B
Department of Agricultural Chemistry, Oregon State University, Corvallis 97331.
J Bacteriol. 1990 Jun;172(6):3269-77. doi: 10.1128/jb.172.6.3269-3277.1990.
The C1 repressor of bacteriophage P1 acts via 14 or more distinct operators. This repressor represses its own synthesis as well as the synthesis of other gene products. Previously, mutation of an auxiliary regulatory gene, bof, has been shown to increase expression of some C1-regulated P1 genes (e.g., ref) but to decrease expression of others (e.g., ban). In this study the bof gene was isolated on the basis of its ability to depress stimulation of Escherichia coli chromosomal recombination by the P1 ref gene, if and only if a source of C1 was present. C1 alone, but not Bof alone, was partially effective. The bofDNA sequence encodes an 82-codon reading frame that begins with a TTG codon and includes the sites of the bof-1(Am) mutation and a bof::Tn5 null mutation. Expression of ref::lacZ and cl::lacZ fusion genes was partially repressed in trans by a P1 bof-1 prophage or by plasmid-encoded C1 alone, which was in agreement with effects on Ref-stimulated recombination and with previous indirect evidence for c1 autoregulation. Repression of both fusion genes by plasmid-encoded C1 plus Bof or by a P1 bof+ prophage was more complete. When the C1 source also included a 0.7-kilobase region upstream from C1 which encodes the coi gene, repression of both c1::lacZ and ref::lacZ by C1 alone or by C1 plus Bof was much less effective, as if Coi interfered with C1 repressor function.
噬菌体P1的C1阻遏物通过14个或更多不同的操纵基因起作用。这种阻遏物抑制自身的合成以及其他基因产物的合成。以前的研究表明，辅助调节基因bof发生突变会增加一些C1调节的P1基因的表达（例如，参考文献），但会降低其他一些基因的表达（例如，ban）。在本研究中，bof基因是根据其抑制P1 ref基因对大肠杆菌染色体重组的刺激作用的能力而分离出来的，条件是且仅是存在C1来源。单独的C1有部分效果，但单独的Bof没有效果。bofDNA序列编码一个82个密码子的阅读框，该阅读框从TTG密码子开始，包括bof-1（Am）突变位点和一个bof::Tn5无效突变位点。ref::lacZ和cl::lacZ融合基因的表达在反式中被P1 bof-1原噬菌体或仅被质粒编码的C1部分抑制，这与对Ref刺激的重组的影响以及先前关于c1自动调节的间接证据一致。质粒编码的C1加Bof或P1 bof+原噬菌体对两个融合基因的抑制作用更完全。当C1来源还包括C1上游一个0.7千碱基的区域（该区域编码coi基因）时，单独的C1或C1加Bof对c1::lacZ和ref::lacZ的抑制作用要小得多，就好像Coi干扰了C1阻遏物的功能。
