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Dual Two-Component Regulatory Systems Are Involved in Aromatic Compound Degradation in a Polychlorinated-Biphenyl Degrader, Rhodococcus jostii RHA1

  • Hisashi Takeda
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
  • Jun Shimodaira
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
  • Kiyoshi Yukawa
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
  • Naho Hara
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
  • Daisuke Kasai
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
  • Keisuke Miyauchi
    Department of Civil and Environmental Engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo, Miyagi 985-8537, Japan
  • Eiji Masai
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
  • Masao Fukuda
    Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan

Abstract

<jats:title>ABSTRACT</jats:title> <jats:p> A Gram-positive polychlorinated-biphenyl (PCB) degrader, <jats:italic>Rhodococcus jostii</jats:italic> RHA1, degrades PCBs by cometabolism with biphenyl. A two-component BphS1T1 system encoded by <jats:italic>bphS1</jats:italic> and <jats:italic>bphT1</jats:italic> (formerly <jats:italic>bphS</jats:italic> and <jats:italic>bphT</jats:italic> ) is responsible for the transcription induction of the five gene clusters, <jats:italic>bphAaAbAcAdC1B1</jats:italic> , <jats:italic>etbAa1Ab1CbphD1</jats:italic> , <jats:italic>etbAa2Ab2AcD2</jats:italic> , <jats:italic>etbAdbphB2</jats:italic> , and <jats:italic>etbD1</jats:italic> , which constitute multiple enzyme systems for biphenyl/PCB degradation. The <jats:italic>bphS2</jats:italic> and <jats:italic>bphT2</jats:italic> genes, which encode BphS2 and BphT2, virtually identical to BphS1 (92%) and BphT1 (97%), respectively, were characterized. BphS2T2 induced the activation of the <jats:italic>bphAa</jats:italic> promoter in a host, <jats:italic>Rhodococcus erythropolis</jats:italic> IAM1399, in the presence of a variety of aromatics, including benzene, toluene, ethylbenzene, xylenes, isopropylbenzene, and chlorinated benzenes, as effectively as BphS1T1. The substrate spectrum of BphS2T2 was the same as that of BphS1T1, except for biphenyl, which is a substrate only for BphS1T1. BphS2T2 activated transcription from the five promoters of biphenyl/PCB degradation enzyme gene clusters as effectively as BphS1T1. The targeted disruptions of the <jats:italic>bphS1</jats:italic> , <jats:italic>bphS2</jats:italic> , <jats:italic>bphT1</jats:italic> , and <jats:italic>bphT2</jats:italic> genes indicated that all these genes are involved in the growth of RHA1 on aromatic compounds. The hybrid system with <jats:italic>bphS1</jats:italic> and <jats:italic>bphT2</jats:italic> and that with <jats:italic>bphS2</jats:italic> and <jats:italic>bphT1</jats:italic> were constructed, and both systems conducted induced activation of the <jats:italic>bphAa</jats:italic> promoter, indicating cross-communication. These results indicated that RHA1 employs not only multiple enzyme systems, but also dual regulatory systems for biphenyl/PCB degradation. Comparison of the sequences, including <jats:italic>bphS2T2</jats:italic> , with the <jats:italic>bphS1T1</jats:italic> -containing sequences and the corresponding sequences in other rhodococcal degraders suggests that <jats:italic>bphS2T2</jats:italic> might have originated from <jats:italic>bphS1T1</jats:italic> . </jats:p>

Journal

  • Journal of Bacteriology

    Journal of Bacteriology 192 (18), 4741-4751, 2010-09-15

    American Society for Microbiology

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