Brolle D F, Pape H, Hopwood D A, Kieser T
John Innes Institute, John Innes Centre, Norwich, UK.
Mol Microbiol. 1993 Oct;10(1):157-70. doi: 10.1111/j.1365-2958.1993.tb00912.x.
pIJ903, a bifunctional derivative of the 31.4 kb low-copy-number, conjugative Streptomyces plasmid SCP2*, was mutagenized in Streptomyces lividans using Tn4560. Mutant plasmids differing in their transfer frequencies, chromosome mobilization abilities, pock formation, and complementation properties were isolated. The mutations defined five transfer-related genes, traA, traB, traC, traD and spd, clustered in a region of 9 kb. The deduced sequences of the putative TraA and TraB proteins showed no overall similarity to known protein sequences, but the phenotype of traA mutant plasmids and sequence motifs in the putative TraA protein suggested that it might be a DNA helicase.
pIJ903是31.4 kb低拷贝数的接合型链霉菌质粒SCP2*的双功能衍生物，它在变铅青链霉菌中利用Tn4560进行诱变。分离出了转移频率、染色体动员能力、噬菌斑形成和互补特性不同的突变体质粒。这些突变确定了五个与转移相关的基因，即traA、traB、traC、traD和spd，它们聚集在一个9 kb的区域。推测的TraA和TraB蛋白的推导序列与已知蛋白序列没有整体相似性，但traA突变体质粒的表型和推测的TraA蛋白中的序列基序表明它可能是一种DNA解旋酶。
