Rojo F, Alonso J C
Centro Nacional de Biotecnología, C.S.I.C., Campus Universidad Autónoma, Madrid, Spain.
Nucleic Acids Res. 1994 May 25;22(10):1855-60. doi: 10.1093/nar/22.10.1855.
The beta protein encoded by the Streptococcus pyogenes plasmid pSM19035 is a site-specific recombinase involved in both resolution of plasmid multimers into monomers and DNA inversion. It has been proposed that the DNA region to which the beta recombinase binds to mediate recombination includes a promoter from which orf alpha and the beta gene are transcribed. We have determined the sites at which transcription of the orf alpha and the beta gene initiates in vitro and we have demonstrated that highly purified beta recombinase acts as a repressor of its own synthesis. The promoters are located within the beta recombinase binding site, which we have defined previously. The binding of the beta recombinase to its target site does not seem to exclude RNA polymerase from the promoter, despite the overlapping of their binding sites. Therefore, it is likely that the beta recombinase does not repress transcription by a mere steric hindrance on RNA polymerase binding.
化脓性链球菌质粒pSM19035编码的β蛋白是一种位点特异性重组酶，参与质粒多聚体分解为单体以及DNA倒位过程。有人提出，β重组酶结合以介导重组的DNA区域包含一个启动子，orfα和β基因从该启动子转录。我们已经确定了orfα和β基因在体外转录起始的位点，并且我们已经证明，高度纯化的β重组酶可作为其自身合成的阻遏物。这些启动子位于我们之前定义的β重组酶结合位点内。尽管β重组酶与其靶位点的结合位点有重叠，但β重组酶与靶位点的结合似乎并不排除RNA聚合酶与启动子的结合。因此，β重组酶不太可能仅仅通过对RNA聚合酶结合的空间位阻来抑制转录。
