Convergent evolution sheds light on the anti-β-elimination mechanism common to family 1 and 10 polysaccharide lyases
Convergent evolution sheds light on the anti-β-elimination mechanism common to family 1 and 10 polysaccharide lyases
复制标题
DOI：
10.1073/pnas.182431199
复制
发表时间：
2002-09-17
影响因子：
11.1
通讯作者：
Davies, GJ
中科院分区：
文献类型：
--
作者：
Charnock, SJ;Brown, IE;Davies, GJ
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 Angstrom, 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/Ca(2+) 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 Ca(2+) ion, the positioning of an arginine catalytic base in close proximity to the a-carbon hydrogen and numerous other conserved enzyme-substrate interactions, considered in light of mutagenesis data for both families, suggest a generic polysaccharicle anti-beta-elimination mechanism.
