title: Novel regulator MphX represses activation of phenol hydroxylase genes caused by a XylR/DmpR-type regulator MphR in Acinetobacter calcoaceticus.
abstract: Acinetobacter calcoaceticus PHEA-2 utilizes phenol as its sole carbon and energy source and has a multi-component phenol hydroxylase-encoding gene operon (mphKLMNOP) for phenol degradation. Two additional genes, mphR and mphX, were found upstream and downstream of mphKLMNOP, respectively. The mphR gene encodes a XylR/DmpR-type regulator-like protein and is transcribed in the opposite direction to mphKLMNOP. The mphX gene is transcribed in the same direction as mphKLMNOP and encodes a protein with 293 amino acid residues showing weak identity with some unknown proteins encoded in the meta-cleavage pathway gene clusters for aromatic compound degradation. Disruption of mphR by homologous recombination resulted in the loss of phenol degradation while disruption of mphX caused significantly faster phenol degradation than in the wild type strain. Transcriptional assays for mphK, mphR, and mphX revealed that mphR activated mphKLMNOP transcription in the presence of phenol, but mphX partially repressed this activation. Gel mobility-shift assay demonstrated a direct interaction of MphR with the mphK promoter region. These results indicate the involvement of a novel repressor protein MphX in transcriptional regulation of phenol hydroxylase genes caused by a XylR/DmpR-type regulator MphR.
authors: College of Biological Sciences, China Agricultural University, Beijing, China.
authors: Haiying
authors: H
authors: Yu
authors: Zixin
authors: Z
authors: Peng
authors: Yuhua
authors: Y
authors: Zhan
authors: Jin
authors: J
authors: Wang
authors: Yongliang
authors: Y
authors: Yan
authors: Ming
authors: M
authors: Chen
authors: Wei
authors: W
authors: Lu
authors: Shuzhen
authors: S
authors: Ping
authors: Wei
authors: W
authors: Zhang
authors: Zhonglin
authors: Z
authors: Zhao
authors: Shuying
authors: S
authors: Li
authors: Masahiro
authors: M
authors: Takeo
authors: Min
authors: M
authors: Lin
mesh_terms: D016954:Acinetobacter calcoaceticus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006899:Mixed Function Oxygenases; C022336:phenol 2-monooxygenase