Legoux R, Lelong P, Jourde C, Feuillerat C, Capdevielle J, Sure V, Ferran E, Kaghad M, Delpech B, Shire D, Ferrara P, Loison G, Salomé M
Department of Microbiology, Sanofi-Recherche, Labege, France.
J Bacteriol. 1996 Dec;178(24):7260-4. doi: 10.1128/jb.178.24.7260-7264.1996.
The structure of the capsular polysaccharide of Escherichia coli K5 is identical to that of N-acetyl-heparosan, a nonsulfated precursor of heparin, which makes this E. coli antigen an attractive starting point for the chemical synthesis of analogs of low-molecular-weight heparin. This polysaccharide is synthesized as a high-molecular-weight molecule that can be depolymerized by an enzyme displaying endo-beta-eliminase activity. The eliminase-encoding gene, designated elmA, has been cloned from E. coli K5 by expression in E. coli K-12. The K-12 genome is devoid of the elmA sequence. The elmA gene product is 820 amino acids long. Active recombinant eliminase is produced by K-12 cells in both cell-bound and secreted forms. Deletion analyses have shown that the C terminus and the N terminus are required for activity and secretion, respectively.
大肠杆菌K5荚膜多糖的结构与N-乙酰肝素（肝素的非硫酸化前体）相同，这使得这种大肠杆菌抗原成为化学合成低分子量肝素类似物的一个有吸引力的起始点。这种多糖以高分子量分子形式合成，可被具有内切β-消除酶活性的酶解聚。已通过在大肠杆菌K-12中表达从大肠杆菌K5中克隆出编码该消除酶的基因，命名为elmA。K-12基因组中没有elmA序列。elmA基因产物长度为820个氨基酸。活性重组消除酶由K-12细胞以细胞结合和分泌两种形式产生。缺失分析表明，C末端和N末端分别是活性和分泌所必需的。
