Kokoska R J, Steege D A
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Bacteriol. 1998 Jun;180(12):3245-9. doi: 10.1128/JB.180.12.3245-3249.1998.
The products of in-frame overlapping genes II and X carried by the filamentous phage f1 genome are proteins with required but opposing functions in phage DNA replication. Their normal relative levels are important for continuous production of phage DNA without killing infected Escherichia coli hosts. Here we identify several factors responsible for determining the relative levels of pII and pX and that, if perturbed, alter the normal distribution of the phage DNA species in infected hosts. Translation of the two proteins is essentially relegated to separate mRNAs. The mRNAs encoding genes II and X are also differentially sensitive to cleavage dependent on rne, the gene encoding the only E. coli endo-RNase known to have a global role in mRNA stability. Whereas pII levels are limited at the level of mRNA stability, normal pX levels require transcription in sufficient amounts from the promoter for the smaller mRNA encoding only pX.
丝状噬菌体f1基因组携带的框内重叠基因II和X的产物是在噬菌体DNA复制中具有必需但相反功能的蛋白质。它们的正常相对水平对于在不杀死受感染的大肠杆菌宿主的情况下持续产生噬菌体DNA很重要。在这里，我们确定了几个负责决定pII和pX相对水平的因素，这些因素如果受到干扰，会改变受感染宿主中噬菌体DNA种类的正常分布。这两种蛋白质的翻译基本上被分配到不同的mRNA上。编码基因II和X的mRNA对依赖rne的切割也有不同的敏感性，rne是编码唯一已知在mRNA稳定性中起全局作用的大肠杆菌内切核糖核酸酶的基因。虽然pII水平在mRNA稳定性水平上受到限制，但正常的pX水平需要从仅编码pX的较小mRNA的启动子进行足够量的转录。
