title: Involvement of the TetR-Type Regulator PaaR in the Regulation of Pristinamycin I Biosynthesis through an Effect on Precursor Supply in Streptomyces pristinaespiralis.
abstract: Pristinamycin I (PI), produced by Streptomyces pristinaespiralis, is a streptogramin type B antibiotic, which contains two proteinogenic and five aproteinogenic amino acid precursors. PI is coproduced with pristinamycin II (PII), a member of streptogramin type A antibiotics. The PI biosynthetic gene cluster has been cloned and characterized. However, thus far little is understood about the regulation of PI biosynthesis. In this study, a TetR family regulator (encoded by SSDG_03033) was identified as playing a positive role in PI biosynthesis. Its homologue, PaaR, from Corynebacterium glutamicum serves as a transcriptional repressor of the paa genes involved in phenylacetic acid (PAA) catabolism. Herein, we also designated the identified regulator as PaaR. Deletion of paaR led to an approximately 70% decrease in PI production but had little effect on PII biosynthesis. Identical to the function of its homologue from C. glutamicum, PaaR is also involved in the suppression of paa expression. Given that phenylacetyl coenzyme A (PA-CoA) is the common intermediate of the PAA catabolic pathway and the biosynthetic pathway of L-phenylglycine (L-Phg), the last amino acid precursor for PI biosynthesis, we proposed that derepression of the transcription of paa genes in a ΔpaaR mutant possibly diverts more PA-CoA to the PAA catabolic pathway, thereby with less PA-CoA metabolic flux toward L-Phg formation, thus resulting in lower PI titers. This hypothesis was verified by the observations that PI production of a ΔpaaR mutant was restored by L-Phg supplementation as well as by deletion of the paaABCDE operon in the ΔpaaR mutant. Altogether, this study provides new insights into the regulation of PI biosynthesis by S. pristinaespiralis.
  
  
  OBJECTIVE
  A better understanding of the regulation mechanisms for antibiotic biosynthesis will provide valuable clues for Streptomyces strain improvement. Herein, a TetR family regulator PaaR, which serves as the repressor of the transcription of paa genes involved in phenylacetic acid (PAA) catabolism, was identified as playing a positive role in the regulation of pristinamycin I (PI) by affecting the supply of one of seven amino acid precursors, L-phenylglycine, in Streptomyces pristinaespiralis. To our knowledge, this is the first report describing the interplay between PAA catabolism and antibiotic biosynthesis in Streptomyces strains. Considering that the PAA catabolic pathway and its regulation by PaaR are widespread in antibiotic-producing actinomycetes, it could be suggested that PaaR-dependent regulation of antibiotic biosynthesis might commonly exist.
authors: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors: Yawei
authors: Y
authors: Zhao
authors: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors: Rongrong
authors: R
authors: Feng
authors: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors: Guosong
authors: G
authors: Zheng
authors: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors: Jinzhong
authors: J
authors: Tian
authors: Shanghai Laiyi Center for Biopharmaceuticals R&D, Shanghai, People's Republic of China.
authors: Lijun
authors: L
authors: Ruan
authors: Shanghai Laiyi Center for Biopharmaceuticals R&D, Shanghai, People's Republic of China.
authors: Mei
authors: M
authors: Ge
authors: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, People's Republic of China.
authors: Weihong
authors: W
authors: Jiang
authors: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China yhlu@sibs.ac.cn.
authors: Yinhua
authors: Y
authors: Lu
mesh_terms: D000105:Acetyl Coenzyme A / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D005809:Genes, Regulator / Q000502:physiology*; D005998:Glycine / Q000031:analogs & derivatives / Q000378:metabolism; D015394:Molecular Structure; D025762:Pristinamycin / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D013302:Streptomyces / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D025762:Pristinamycin; C008852:2-phenylglycine; D000105:Acetyl Coenzyme A; C037816:phenylacetyl-coenzyme A; D005998:Glycine