Hara O, Horinouchi S, Uozumi T, Beppu T
J Gen Microbiol. 1983 Sep;129(9):2939-44. doi: 10.1099/00221287-129-9-2939.
A-factor is a potent pleiotropic effector produced by Streptomyces griseus and is essential for streptomycin production and spore formation in this organism. Its production is widely distributed among various actinomycetes including Streptomyces coelicolor A3(2). Genetic analysis of A-factor production was carried out with S. coelicolor A3(2), and two closely linked loci for A-factor mutations (afsA and B) were identified between cysD and leuB on the chromosomal linkage map. In contrast, genetic crosses of A-factor-negative mutants of S. griseus, using a protoplast fusion technique, failed to give a fixed locus for A-factor gene(s) and suggested involvement of an extrachromosomal or transposable genetic element in A-factor synthesis in this organism.
A因子是由灰色链霉菌产生的一种强效多效效应物，对于该生物体中链霉素的产生和孢子形成至关重要。其产生在包括天蓝色链霉菌A3(2)在内的各种放线菌中广泛分布。利用天蓝色链霉菌A3(2)对A因子的产生进行了遗传分析，在染色体连锁图谱上的cysD和leuB之间鉴定出了两个与A因子突变紧密连锁的基因座（afsA和B）。相比之下，利用原生质体融合技术对灰色链霉菌A因子阴性突变体进行遗传杂交，未能确定A因子基因的固定位点，并表明该生物体中A因子合成涉及一个染色体外或可转座的遗传元件。
