Sands J F, Regnier P, Cummings H S, Grunberg-Manago M, Hershey J W
Department of Biological Chemistry, School of Medicine, University of California, Davis 95616.
Nucleic Acids Res. 1988 Nov 25;16(22):10803-16. doi: 10.1093/nar/16.22.10803.
A number of genes encoding proteins involved in transcription and translation are clustered between 68 and 69 minutes on the Escherichia coli genome map and are transcribed clockwise as two operons: the metY operon, containing metY, P15A, nusA, infB; and about a kilobase further downstream, the rpsO and pnp operon. The DNA sequence between infB and rpsO was determined and two open reading frames were detected which code for proteins of 15,200 (P15B) and 35,091 (P35) daltons. Maxicell analysis showed a relatively strong expression of P15B whereas P35 was synthesized more weakly. An overlap of the termination codon of P15B and the initiator codon for P35 suggests that translation of P15B and P35 may be coupled. S1 nuclease mapping of in vivo transcripts between infB and rpsO provided no evidence for major promoters but detected a moderately efficient rho-independent terminator between infB and P15B. The results indicate that P15B and P35 are expressed as part of the metY operon, but that some transcriptional read through into the rpsO operon also occurs, thereby, functionally linking the expression of these two complex systems.
一些编码参与转录和翻译的蛋白质的基因聚集在大肠杆菌基因组图谱上68至69分钟之间的区域，作为两个操纵子顺时针转录：metY操纵子，包含metY、P15A、nusA、infB；在下游约1千碱基处是rpsO和pnp操纵子。测定了infB和rpsO之间的DNA序列，检测到两个开放阅读框，它们编码15200道尔顿（P15B）和35091道尔顿（P35）的蛋白质。大细胞分析显示P15B表达相对较强，而P35合成较弱。P15B的终止密码子与P35的起始密码子重叠，这表明P15B和P35的翻译可能是偶联的。对infB和rpsO之间体内转录本进行S1核酸酶作图，未发现主要启动子的证据，但在infB和P15B之间检测到一个中等效率的不依赖ρ因子的终止子。结果表明，P15B和P35作为metY操纵子的一部分表达，但也存在一些转录通读进入rpsO操纵子的情况，从而在功能上连接了这两个复杂系统的表达。
