Boraston Alisdair B, Abbott D Wade
Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Feb 1;68(Pt 2):129-33. doi: 10.1107/S1744309111055400. Epub 2012 Jan 21.
Pectin methylesterases (PMEs) are family 8 carbohydrate esterases (CE8s) which remove the methyl group from methylesterified galacturonic acid (GalA) residues within pectin. Although the role of pectinases such as PMEs within dedicated phytopathogens has been well established, the significance of homologous enzymes found within the genomes of human enteropathogens remains to be determined. Presented here is the low-resolution (3.5 Å) structure of the CE8 from Yersinia enterocolitica (YeCE8). The high degree of structural conservation in the topology of the active-site cleft and catalytic apparatus that is shared with a characterized PME from a bacterial phytopathogen (i) indicates that YeCE8 is active on methylated pectin and (ii) highlights a more prominent role for pectin utilization in Yersinia than in other enteropathogenic species.
果胶甲基酯酶（PMEs）属于第8家族碳水化合物酯酶（CE8s），可从果胶中甲基酯化的半乳糖醛酸（GalA）残基上去除甲基基团。尽管诸如PMEs等果胶酶在特定植物病原体中的作用已得到充分证实，但人类肠道病原体基因组中发现的同源酶的意义仍有待确定。本文展示了小肠结肠炎耶尔森菌（YeCE8）中CE8的低分辨率（3.5 Å）结构。其活性位点裂隙和催化装置的拓扑结构与一种来自细菌性植物病原体的已表征PME高度保守，这表明：（i）YeCE8对甲基化果胶具有活性；（ii）突出了果胶利用在耶尔森菌中比在其他肠道致病物种中发挥更重要的作用。
