Structure of XC6422 from Xanthomonas campestris at 1.6 Å resolution: a small serine α/β-hydrolase
- Institute of Biochemistry, National Chung-Hsing University, Taichung 40227,Taiwan (China)
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei,Taiwan (China)
The crystal structure of a conserved hypothetical protein from X. campestris has been determined to a resolution of 1.6 Å. The determined X. campestris structure shows that it belongs to the superfamily of serine α/β hydrolase, with an extra strand preceding the first β-strand to lead to extensive subunit interactions in the crystal. 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.
- OSTI ID:
- 22360240
- Journal Information:
- Acta Crystallographica. Section F, Vol. 62, Issue Pt 6; Other Information: PMCID: PMC2243109; PMID: 16754966; PUBLISHER-ID: sx5051; OAI: oai:pubmedcentral.nih.gov:2243109; Copyright (c) International Union of Crystallography 2006; Country of input: International Atomic Energy Agency (IAEA); ISSN 1744-3091
- Country of Publication:
- United Kingdom
- Language:
- English
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