Genomic and transcriptomic insights into the thermo-regulated biosynthesis of validamycin in Streptomyces hygroscopicus 5008.
BMC Genomics, 2012/7/24;13:337.
Wu H[1], Qu S, Lu C, Zheng H, Zhou X, Bai L, Deng Z
Affiliations
PMID: 22827618DOI: 10.1186/1471-2164-13-337
Impact factor: 4.547
Abstract
background: Streptomyces hygroscopicus 5008 has been used for the production of the antifungal validamycin/jinggangmycin for more than 40 years. A high yield of validamycin is achieved by culturing the strain at 37°C, rather than at 30°C for normal growth and sporulation. The mechanism(s) of its thermo-regulated biosynthesis was largely unknown.
results: The 10,383,684-bp genome of strain 5008 was completely sequenced and composed of a linear chromosome, a 164.57-kb linear plasmid, and a 73.28-kb circular plasmid. Compared with other Streptomyces genomes, the chromosome of strain 5008 has a smaller core region and shorter terminal inverted repeats, encodes more α/β hydrolases, major facilitator superfamily transporters, and Mg2+/Mn2+-dependent regulatory phosphatases. Transcriptomic analysis revealed that the expression of 7.5% of coding sequences was increased at 37°C, including biosynthetic genes for validamycin and other three secondary metabolites. At 37°C, a glutamate dehydrogenase was transcriptionally up-regulated, and further proved its involvement in validamycin production by gene replacement. Moreover, efficient synthesis and utilization of intracellular glutamate were noticed in strain 5008 at 37°C, revealing glutamate as the nitrogen source for validamycin biosynthesis. Furthermore, a SARP-family regulatory gene with enhanced transcription at 37°C was identified and confirmed to be positively involved in the thermo-regulation of validamycin production by gene inactivation and transcriptional analysis.
conclusions: Strain 5008 seemed to have evolved with specific genomic components to facilitate the thermo-regulated validamycin biosynthesis. The data obtained here will facilitate future studies for validamycin yield improvement and industrial bioprocess optimization.
MeSH terms
Bacterial Proteins; Carbon; Chromosomes, Bacterial; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genomics; Glutamates; Inositol; Molecular Sequence Data; Multigene Family; Nitrogen; Plasmids; Sequence Analysis, DNA; Streptomyces; Telomere; Temperature; Transcriptome
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