Structure of XC6422 from Xanthomonas campestris at 1.6 Å resolution: A small serine α/β-hydrolase

Chao Yu Yang, Ko Hsin Chin, Chia Cheng Chou, Andrew H.J. Wang, Shan Ho Chou

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


XC6422 is a conserved hypothetical protein from Xanthomonas campestris pathovar campestris (Xcc), a Gram-negative yellow-pigmented pathogenic bacterium that causes black rot, one of the major worldwide diseases of cruciferous crops. The protein consists of 220 amino acids and its structure has been determined to 1.6 Å resolution using the multi-wavelength anomalous dispersion (MAD) method. Although it has very low sequence identity to protein sequences in the PDB (less than 20%), the determined structure nevertheless shows that it belongs to the superfamily of serine α/β-hydrolases, with an active site that is fully accessible to solvent owing to the absence of a lid domain. Modelling studies with the serine esterase inhibitor E600 indicate that XC6422 adopts a conserved Ser-His-Asp catalytic triad common to this superfamily and has a preformed oxyanion hole for catalytic activation. These structural features suggest that XC6422 is most likely to be a hydrolase active on a soluble ester or a small lipid. An extra strand preceding the first β-strand in the canonical α/β-hydrolase fold leads to extensive subunit interactions between XC6422 monomers, which may explain why XC6422 crystals of good diffraction quality can grow to dimensions of up to 1.5 mm in a few days.

Original languageEnglish
Pages (from-to)498-503
Number of pages6
JournalActa Crystallographica Section F: Structural Biology and Crystallization Communications
Issue number6
Publication statusPublished - Jun 2006
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Genetics
  • Condensed Matter Physics


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