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

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)951-966
Number of pages16
JournalJournal of Molecular Biology
Volume390
Issue number5
DOIs
Publication statusPublished - Jul 31 2009
Externally publishedYes

Keywords

  • atypical 2-Cys
  • BCP
  • peroxide oxidoreduction pathway
  • Prxs
  • ROS

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Molecular Biology

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