1gxn
From Proteopedia
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FAMILY 10 POLYSACCHARIDE LYASE FROM CELLVIBRIO CELLULOSA
Overview
Enzyme-catalyzed beta-elimination of sugar uronic acids, exemplified by the degradation of plant cell wall pectins, plays an important role in a wide spectrum of biological processes ranging from the recycling of plant biomass through to pathogen virulence. The three-dimensional crystal structure of the catalytic module of a "family PL-10" polysaccharide lyase, Pel10Acm from Cellvibrio japonicus, solved at a resolution of 1.3 A, reveals a new polysaccharide lyase fold and is the first example of a polygalacturonic acid lyase that does not exhibit the "parallel beta-helix" topology. The "Michaelis" complex of an inactive mutant in association with the substrate trigalacturonate/Ca2+ reveals the catalytic machinery harnessed by this polygalacturonate lyase, which displays a stunning resemblance, presumably through convergent evolution, to the tetragalacturonic acid complex observed for a structurally unrelated polygalacturonate lyase from family PL-1. Common coordination of the -1 and +1 subsite saccharide carboxylate groups by a protein-liganded Ca2+ ion, the positioning of an arginine catalytic base in close proximity to the alpha-carbon hydrogen and numerous other conserved enzyme-substrate interactions, considered in light of mutagenesis data for both families, suggest a generic polysaccharide anti-beta-elimination mechanism.
About this Structure
1GXN is a Single protein structure of sequence from Cellvibrio japonicus. Active as Pectate lyase, with EC number 4.2.2.2 Full crystallographic information is available from OCA.
Reference
Convergent evolution sheds light on the anti-beta -elimination mechanism common to family 1 and 10 polysaccharide lyases., Charnock SJ, Brown IE, Turkenburg JP, Black GW, Davies GJ, Proc Natl Acad Sci U S A. 2002 Sep 17;99(19):12067-72. Epub 2002 Sep 9. PMID:12221284
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