A-factor and streptomycin biosynthesis in Streptomyces griseus.
Accumulating data have shown that the metabolites with a gamma-butyrolactone ring functions as an autoregulatory factor or a microbial hormone for the expression of various phenotypes not only in a variety of Streptomyces spp. but also in the distantly related bacteria. A-factor, as a representative of this type of autoregulators, triggers streptomycin biosynthesis and cellular differentiation in Streptomyces griseus. A model for the A-factor regulatory cascade on the basis of recent work is as follows. At an early step in the A-factor regulatory relay, the positive A-factor signal is first received by an A-factor receptor protein that is comparable in every aspect to eukaryotic hormone receptors, and then, via one or more regulatory steps, transmitted to an A-factor-responsive protein that binds to the upstream activation sequence of the strR gene, a regulatory gene in the streptomycin biosynthetic gene cluster. The StrR protein thus induced appears to activate the other streptomycin biosynthetic genes. This review summarizes the characteristics of A-factor as a microbial hormone and the A-factor regulatory relay leading to streptomycin production.
Horinouchi
S
S
Department of Agricultural Chemistry, University of Tokyo, Japan.
Beppu
T
T
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008957:Models, Genetic; D015183:Restriction Mapping; D013305:Streptomyces griseus / Q000235:genetics / Q000378:metabolism*; D013307:Streptomycin / Q000096:biosynthesis*; D014158:Transcription, Genetic
C025035:A-factor (Streptomyces); D015107:4-Butyrolactone; D013307:Streptomycin