title: Role of σ-factor (orf21) in clavulanic acid production in Streptomyces clavuligerus NRRL3585.
abstract: A putative sigma factor gene, orf21, was disrupted or overexpressed in the wild-type clavulanic acid (CA) producer Streptomyces clavuligerus NRRL3585 and characterized. An orf21 mutant (Streptomyces clavuligerus HN14) of S. clavuligerus was obtained by insertional inactivation via double-crossover. Although there was little reduction of sporulation in the mutant, the growth pattern was similar between mutant and wild-type. The production was reduced by 10-15% in S. clavuligerus HN14 compared to that in wild-type. Overexpression of orf21 in wild-type cells caused hyperproduction of spores on solid medium and increased clavulanic acid production by 1.43-fold. The overexpression of orf21 in wild-type S. clavuligerus stimulated the expression of the early clavulanic acid genes, ceas2 and cas2, and the regulatory gene, ccaR, as demonstrated by RT-PCR. The elevation of the ceas2, cas2 and ccaR transcripts was consistent with the enhanced production of clavulanic acid.
authors.affiliation: Institute of Biomolecule Reconstruction (iBR), Department of Pharmaceutical Engineering, SunMoon University, # 100, Asansi, Chungnam 336-708, Republic of Korea.
authors.forename: Hum Nath
authors.initials: HN
authors.lastname: Jnawali
authors.forename: Kwangkyoung
authors.initials: K
authors.lastname: Liou
authors.forename: Jae Kyung
authors.initials: JK
authors.lastname: Sohng
mesh_terms: D019818:Clavulanic Acid / Q000096:biosynthesis*; D003470:Culture Media / Q000737:chemistry; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D016254:Mutagenesis, Insertional; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development; D013302:Streptomyces / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D003470:Culture Media; D012808:Sigma Factor; D019818:Clavulanic Acid