• KSBB Journal
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• v.24 no.3
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• pp.259-266
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• 2009

AfsR2 in Streptomyces lividans, a 63-amino acid protein with limited sequence homology to Streptomyces sigma factors, has been known for a global regulatory protein stimulating multiple antibiotic biosynthetic pathways. Although the detailed regulatory mechanism of AfsK-AfsR-AfsR2 system has been well characterized, very little information about the AfsR2-dependent down-stream regulatory genes were characterized. Recently, the null mutant of afsS in S. coelicolor (the identical ortholog of afsR2) has been characterized through DNA microarray system, revealing that afsS deletion regulated several genes involved in antibiotic biosynthesis as well as phosphate-starvation. Through comparative DNA microarray analysis of afsR2-overexpressed S. lividans, here we also identify several afsR2-dependent genes involved in phosphate starvation, morphological differentiation, and antibiotic regulation in S. lividans, confirming that the AfsR2 plays an important pleiotrophic regulatory role in Streptomyces species.

• Microbiology and Biotechnology Letters
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• v.34 no.3
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• pp.211-215
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• 2006

AfsR2 is a global regulatory protein involved in the stimulation of secondary metabolite biosynthesis in various Streptomyces species including avermectin-producing S. avermitilis. Among several AfsR2-dependent genes identified from the comparative proteomics, the polyribonucleotide nucleotidyltransferase (PNP) and the glyceraldehyde-3-phosphate dehydrogenase (GPD) genes were previously proposed to regulate the actinorhodin production in S. lividans upon afsR2 over-expression positively and negatively, respectively. To show the biological significance of the PNP and GPD genes in the S. avermitilis strains, these two genes were functionally expressed in both the wild-type and the avermectin-overproducing mutant strains. The PNP gene expression stimulated secondary metabolite production in the wild-type S. avermitilis ATCC31267, but not in the avermectin-overproducing S. avermitilis ATCC31780. Interestingly, the GDP gene expression stimulated secondary metabolite production by 4-fold in the wild-type S. avermitilis ATCC31267 and by 2.5-fold in the avermectin-overproducing S. avermitilis ATCC31780, respectively. These results suggest that the biological significance of the afsR2-dependent PNP and GPD gene expressions on antibiotic biosynthetic regulation could be significantly different depending on Streptomyces species.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.480-484
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• 2010

AfsR2 is a global regulatory protein that stimulates antibiotic biosynthesis in both Streptomyces lividans and S. coelicolor. Previously, various afsR2-dependent genes including a putative abaA-like regulatory gene, SCO4677, were identified through comparative DNA microarray analysis. To further identify the putative SCO4677-dependent proteins, the comparative proteomics-driven approach was applied to the SCO4677-overexpressing strains of S. lividans and S. coelicolor along with the wild-type strains. The 2D gel electrophoresis gave approximately 277 protein spots for S. lividans and 207 protein spots for S. coelicolor, showing different protein expression patterns between the SCO4677-overexpressing strains and the wild-type strains. Further MALDI-TOF analysis revealed that only 18 proteins exhibited similar expression patterns in both S. lividans and S. coelicolor, suggesting that the SCO4677 could encode an abaA-like regulator that controls a few cross-species common proteins as well as many species-specific proteins in Streptomyces species.