title: Crystal structure of polygalacturonase from Erwinia carotovora ssp. carotovora.
abstract: The crystal structure of the 40-kDa endo-polygalacturonase from Erwinia carotovora ssp. carotovora was solved by multiple isomorphous replacement and refined at 1.9 A to a conventional crystallographic R-factor of 0.198 and Rfree of 0.239. This is the first structure of a polygalacturonase and comprises a 10 turn right-handed parallel beta-helix domain with two loop regions forming a "tunnel like" substrate-binding cleft. Sequence conservation indicates that the active site of polygalacturonase is between these two loop regions, and comparison of the structure of polygalacturonase with that of rhamnogalacturonase A from Aspergillus aculeatus enables two conserved aspartates, presumed to be catalytic residues, to be identified. An adjacent histidine, in accord with biochemical results, is also seen. A similarity in overall electrostatic properties of the substrate-binding clefts of polygalacturonase and pectate lyase, which bind and cleave the same substrate, polygalacturonic acid, is also revealed.
authors.affiliation: Institute of Food Research, Reading Laboratory, Earley Gate, Whiteknights Road, Reading RG6 6BZ, United Kingdom. richard.pickersgill@bbsrc.ak.uk
authors.forename: R
authors.initials: R
authors.lastname: Pickersgill
authors.forename: D
authors.initials: D
authors.lastname: Smith
authors.forename: K
authors.initials: K
authors.lastname: Worboys
authors.forename: J
authors.initials: J
authors.lastname: Jenkins
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D006026:Glycoside Hydrolases / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016973:Pectobacterium carotovorum / Q000201:enzymology* / Q000235:genetics; D011096:Polygalacturonase / Q000737:chemistry* / Q000235:genetics; D011133:Polysaccharide-Lyases / Q000737:chemistry; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D011994:Recombinant Proteins; D006026:Glycoside Hydrolases; C067959:rhamnogalacturonase A; D011096:Polygalacturonase; D011133:Polysaccharide-Lyases; C023911:pectate lyase