Kumar S, Srivastava S
Mol Gen Genet. 1983;190(1):27-34. doi: 10.1007/BF00330320.
A number of cya and crp mutants of Escherichia coli HfrH were analyzed for several Tra functions of the F plasmid. The mutants were observed to be deficient in conjugal donor ability, absorption of phages MS2 and Q beta and surface exclusion. These defects were suppressed in cya mutants grown with cAMP supplementation. A cAMP concentration of 3 X 10(-4) M produced maximal suppression of donor ability defect in a cya strain. cAMP did not suppress the Tra- phenotype of crp mutants. Latent periods of MS2 were shorter in cya and crp bacteria. Phage T7 development appeared similar in wild type, cya, and crp cells. It is concluded that tra genes of F plasmid are expressed only to a small extent in cya and crp mutants and that cAMP and its receptor protein are required for the normal expression of tra genes.
对大肠杆菌HfrH的多个cya和crp突变体进行了F质粒几种转移功能的分析。观察到这些突变体在接合供体能力、噬菌体MS2和Qβ的吸附以及表面排斥方面存在缺陷。在用补充了cAMP的培养基中生长的cya突变体中，这些缺陷得到了抑制。3×10⁻⁴ M的cAMP浓度对cya菌株的供体能力缺陷产生了最大程度的抑制。cAMP不能抑制crp突变体的Tra⁻表型。MS2在cya和crp细菌中的潜伏期较短。噬菌体T7在野生型、cya和crp细胞中的发育情况相似。得出的结论是，F质粒的tra基因在cya和crp突变体中仅少量表达，并且cAMP及其受体蛋白是tra基因正常表达所必需的。
