論文

査読有り 国際誌
2015年4月24日

The Radical S-Adenosyl-L-methionine Enzyme QhpD Catalyzes Sequential Formation of Intra-protein Sulfur-to-Methylene Carbon Thioether Bonds.

The Journal of biological chemistry
  • Tadashi Nakai
  • ,
  • Hiroto Ito
  • ,
  • Kazuo Kobayashi
  • ,
  • Yasuhiro Takahashi
  • ,
  • Hiroshi Hori
  • ,
  • Motonari Tsubaki
  • ,
  • Katsuyuki Tanizawa
  • ,
  • Toshihide Okajima

290
17
開始ページ
11144
終了ページ
66
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1074/jbc.M115.638320
出版者・発行元
The American Society for Biochemistry and Molecular Biology, Inc.

The bacterial enzyme designated QhpD belongs to the radical S-adenosyl-L-methionine (SAM) superfamily of enzymes and participates in the post-translational processing of quinohemoprotein amine dehydrogenase. QhpD is essential for the formation of intra-protein thioether bonds within the small subunit (maturated QhpC) of quinohemoprotein amine dehydrogenase. We overproduced QhpD from Paracoccus denitrificans as a stable complex with its substrate QhpC, carrying the 28-residue leader peptide that is essential for the complex formation. Absorption and electron paramagnetic resonance spectra together with the analyses of iron and sulfur contents suggested the presence of multiple (likely three) [4Fe-4S] clusters in the purified and reconstituted QhpD. In the presence of a reducing agent (sodium dithionite), QhpD catalyzed the multiple-turnover reaction of reductive cleavage of SAM into methionine and 5'-deoxyadenosine and also the single-turnover reaction of intra-protein sulfur-to-methylene carbon thioether bond formation in QhpC bound to QhpD, producing a multiknotted structure of the polypeptide chain. Homology modeling and mutagenic analysis revealed several conserved residues indispensable for both in vivo and in vitro activities of QhpD. Our findings uncover another challenging reaction catalyzed by a radical SAM enzyme acting on a ribosomally translated protein substrate.

リンク情報
DOI
https://doi.org/10.1074/jbc.M115.638320
PubMed
https://www.ncbi.nlm.nih.gov/pubmed/25778402
PubMed Central
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4409272