Ham L M, Skurray R
Department of Microbiology, Monash University Clayton, Victoria, Australia.
Mol Gen Genet. 1989 Mar;216(1):99-105. doi: 10.1007/BF00332236.
We report the cloning of finQ, a gene coding for fertility inhibition of the F plasmid, from the IncI R factor R820a. The finQ gene was mapped precisely within a 1.24 kb region by ptac-transposase + min-kan mutagenesis and its product, FinQp, identified as a single polypeptide by means of SDS-polyacrylamide gel electrophoresis. Nucleotide sequencing of the finQ region allowed elucidation of the FinQp amino acid sequence and determination of its precise molecular weight as 39,895 Da. Analysis of the predicted amino acid sequence indicated that FinQp is a positively charged protein possessing a helix-turn-helix DNA binding motif. We propose a possible model for the mechanism by which FinQp terminates transcription within the F plasmid tra region. DNA-DNA hybridization established that all FinQ+ R factors examined have an homologous finQ gene.
我们报道了从IncI R因子R820a中克隆出finQ基因，该基因编码F质粒的育性抑制因子。通过ptac-转座酶+min-kan诱变将finQ基因精确定位在一个1.24 kb的区域内，并通过SDS-聚丙烯酰胺凝胶电泳将其产物FinQp鉴定为单一多肽。对finQ区域进行核苷酸测序，从而阐明了FinQp的氨基酸序列，并确定其精确分子量为39,895 Da。对预测的氨基酸序列分析表明，FinQp是一种带正电荷的蛋白质，具有螺旋-转角-螺旋DNA结合基序。我们提出了一个关于FinQp在F质粒tra区域内终止转录机制的可能模型。DNA-DNA杂交表明，所有检测的FinQ+ R因子都有同源的finQ基因。
