MISC

2010年1月

Structural Insights into Vinyl Reduction Regiospecificity of Phycocyanobilin:Ferredoxin Oxidoreductase (PcyA)

JOURNAL OF BIOLOGICAL CHEMISTRY
  • Yoshinori Hagiwara
  • ,
  • Masakazu Sugishima
  • ,
  • Htoi Khawn
  • ,
  • Hideki Kinoshita
  • ,
  • Katsuhiko Inomata
  • ,
  • Lixia Shang
  • ,
  • J. Clark Lagarias
  • ,
  • Yasuhiro Takahashi
  • ,
  • Keiichi Fukuyama

285
2
開始ページ
1000
終了ページ
1007
記述言語
英語
掲載種別
DOI
10.1074/jbc.M109.055632
出版者・発行元
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Phycocyanobilin: ferredoxin oxidoreductase (PcyA) is the best characterized member of the ferredoxin-dependent bilin reductase family. Unlike other ferredoxin-dependent bilin reductases that catalyze a two-electron reduction, PcyA sequentially reduces D-ring (exo) and A-ring (endo) vinyl groups of biliverdin IX alpha (BV) to yield phycocyanobilin, a key pigment precursor of the light-harvesting antennae complexes of red algae, cyanobacteria, and cryptophytes. To address the structural basis for the reduction regiospecificity of PcyA, we report new high resolution crystal structures of bilin substrate complexes of PcyA from Synechocystis sp. PCC6803, all of which lack exo-vinyl reduction activity. These include the BV complex of the E76Q mutant as well as substrate-bound complexes of wild-type PcyA with the reaction intermediate 18(1),18(2)-dihydrobiliverdin IX alpha (18EtBV) and with biliverdin XIII alpha (BV13), a synthetic substrate that lacks an exo-vinyl group. Although the overall folds and the binding sites of the U-shaped substrates of all three complexes were similar with wild-type PcyA-BV, the orientation of the Glu-76 side chain, which was in close contact with the exo-vinyl group in PcyA-BV, was rotated away from the bilin D-ring. The local structures around the A-rings in the three complexes, which all retain the ability to reduce the A-ring of their bound pigments, were nearly identical with that of wild-type PcyA-BV. Consistent with the proposed proton-donating role of the carboxylic acid side chain of Glu-76 for exo-vinyl reduction, these structures reveal new insight into the reduction regiospecificity of PcyA.

リンク情報
DOI
https://doi.org/10.1074/jbc.M109.055632
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000273258200020&DestApp=WOS_CPL
ID情報
  • DOI : 10.1074/jbc.M109.055632
  • ISSN : 0021-9258
  • Web of Science ID : WOS:000273258200020

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