BACKGROUND/AIMS A-factor, a γ-butyrolactone autoregulator, in Streptomyces griseus is involved in the regulation of differentiation and antibiotic production. Here we studied the S. griseus B2682-AFN (A-factor negative) bald mutant that harbors a nonsense mutation in the afsR gene encoding a pleiotropic regulator. Our aim was to prove that this mutation is the cause of the A-factor deficiency in AFN. We also studied whether AfsR regulates A-factor production by AfsA, which is supposed to be the only specific key enzyme in A-factor biosynthesis. METHODS Wild afsR was cloned to the pHJL401 shuttle vector and was transformed to the S. griseus AFN and B2682 strains. During phenotypic characterization, sporulation, antibiotic, protease, A-factor, and AfsA protein production were studied. RESULTS Transformation of AFN by a wild afsR restored its phenotype including sporulation, antibiotic, extracellular protease, and A-factor production. Introduction of afsR to the B2682 wild-type strain resulted in antibiotic and extracellular protease overproduction that was accompanied with an elevated A-factor level. AfsA was detected both in AFN and B2682. CONCLUSIONS AfsR has an effect on the regulation of A-factor production in S. griseus. The presence of AfsA is not sufficient for normal A-factor production. AfsR regulates A-factor biosynthesis independently of AfsA.

中文翻译：

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afsR中的突变导致灰链霉菌B2682中的A因子缺乏。

背景/目的灰链霉菌中的A因子γ-丁内酯自动调节剂参与分化和抗生素产生的调节。在这里，我们研究了灰褐色链球菌B2682-AFN（A因子阴性）秃头突变体，该突变体在编码多效性调节剂的afsR基因中包含无意义的突变。我们的目的是证明这种突变是AFN中A因子缺乏的原因。我们还研究了AfsR是否调节AfsA产生的A因子，AfsA被认为是A因子生物合成中唯一的特定关键酶。方法将野生型afsR克隆至pHJL401穿梭载体，并转化至灰链霉菌AFN和B2682菌株。在表型表征过程中，研究了孢子形成，抗生素，蛋白酶，A因子和AfsA蛋白的产生。结果野生afsR对AFN的转化恢复了其表型，包括孢子形成，抗生素，细胞外蛋白酶和A因子产生。将afsR导入B2682野生型菌株会导致抗生素和细胞外蛋白酶的过量生产，并伴随A因子水平升高。在AFN和B2682中均检测到AfsA。结论AfsR对灰链霉菌中A因子的产生具有调节作用。AfsA的存在不足以产生正常的A因子。AfsR独立于AfsA调节A因子的生物合成。在AFN和B2682中均检测到AfsA。结论AfsR对灰链霉菌中A因子的产生具有调节作用。AfsA的存在不足以产生正常的A因子。AfsR独立于AfsA调节A因子的生物合成。在AFN和B2682中均检测到AfsA。结论AfsR对灰链霉菌中A因子的产生具有调节作用。AfsA的存在不足以产生正常的A因子。AfsR独立于AfsA调节A因子的生物合成。