Williams M D, Ouyang T X, Flickinger M C
Department of Biochemistry, University of Minnesota, St. Paul 55108-6106.
Biochem Biophys Res Commun. 1994 May 30;201(1):123-7. doi: 10.1006/bbrc.1994.1677.
Bacteriophage P1 is unable to form plaques on E. coli hosts lacking a functional sspA gene. However, sspA mutants can be infected by P1, resulting in the synthesis of P1 early gene products and accumulation of P1 DNA, but without P1 late gene product formation or host lysis. Overexpression of the stringent starvation protein (SspA) as a glutathione-S-transferase fusion results in complementation of the sspA mutation and production of viable viral particles as in sspA+ strains. This suggests that the GST-SspA protein functions in vivo in a similar manner as native SspA with respect to P1 replication. Here, evidence is presented that shows that SspA binds to RNA-polymerase. This supports the notion that SspA is involved in P1 replication since it is known that P1 requires host RNA-polymerase activity to replicate and this suggests a mechanism by which P1 redirects E. coli RNA-polymerase specificity from P1 early to P1 late genes.
噬菌体P1无法在缺乏功能性sspA基因的大肠杆菌宿主上形成噬菌斑。然而，sspA突变体可被P1感染，导致P1早期基因产物的合成以及P1 DNA的积累，但不会形成P1晚期基因产物或导致宿主裂解。作为谷胱甘肽-S-转移酶融合蛋白的严格饥饿蛋白（SspA）的过表达导致sspA突变得到互补，并像在sspA+菌株中一样产生有活力的病毒颗粒。这表明GST-SspA蛋白在体内对于P1复制的功能与天然SspA相似。在此，有证据表明SspA与RNA聚合酶结合。这支持了SspA参与P1复制的观点，因为已知P1需要宿主RNA聚合酶活性来进行复制，这提示了一种机制，通过该机制P1可将大肠杆菌RNA聚合酶的特异性从P1早期基因重定向至P1晚期基因。
