Insights into the Alkyl Peroxide Reduction Pathway of Xanthomonas campestris Bacterioferritin Comigratory Protein from the Trapped Intermediate-Ligand Complex Structures

Shu Ju Liao, Chao Yu Yang, Ko Hsin Chin, Andrew H.J. Wang, Shan Ho Chou

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26 引文 斯高帕斯(Scopus)

摘要

Considerable insights into the oxidoreduction activity of the Xanthomonas campestris bacterioferritin comigratory protein (XcBCP) have been obtained from trapped intermediate/ligand complex structures determined by X-ray crystallography. Multiple sequence alignment and enzyme assay indicate that XcBCP belongs to a subfamily of atypical 2-Cys peroxiredoxins (Prxs), containing a strictly conserved peroxidatic cysteine (CP48) and an unconserved resolving cysteine (CR84). Crystals at different states, i.e. Free_SH state, Intra_SS state, and Inter_SS state, were obtained by screening the XcBCP proteins from a double C48S/C84S mutant, a wild type, and a C48A mutant, respectively. A formate or an alkyl analog with two water molecules that mimic an alkyl peroxide substrate was found close to the active site of the Free_SH or Inter_SS state, respectively. Their global structures were found to contain a novel substrate-binding pocket capable of accommodating an alkyl chain of no less than 16 carbons. In addition, in the Intra_SS or Inter_SS state, substantial local unfolding or complete unfolding of the CR-helix was detected, with the CP-helix remaining essentially unchanged. This is in contrast to the earlier observation that the CP-helix exhibits local unfolding during disulfide bond formation in typical 2-Cys Prxs. These rich experimental data have enabled us to propose a pathway by which XcBCP carries out its oxidoreduction activity through the alternate opening and closing of the substrate entry channel and the disulfide-bond pocket.

原文英語
頁(從 - 到)951-966
頁數16
期刊Journal of Molecular Biology
390
發行號5
DOIs
出版狀態已發佈 - 7月 31 2009
對外發佈

ASJC Scopus subject areas

  • 生物物理學
  • 結構生物學
  • 分子生物學

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