【摘要】 从苏云金杆菌(Bacillus thuringiensis,B t)entom oc idus亚种HD109菌株中克隆了几丁质酶基因chiA74-HD109,其序列全长为2 031 bp,编码676个氨基酸,GenBank登录号为AY455290。其编码产物与蜡状芽孢杆菌几丁质酶CHiB(AB041932)的相似性达97.9%,与B t kenyae亚种LB IT-82菌株几丁质酶chiA74(AF424979)的相似性达98.4%,与B t pak istan i亚种几丁质酶(U89796)的相似性为83.0%,与B t kurstak i亚种几丁质酶kchi(AY189740)的相似性达97.8%,与B t israe lensis亚种几丁质酶(AF526379)的相似性达96.6%,与B t几丁质酶(AY074882)的相似性达98.4%,与B t sotto亚种几丁质酶(AY129671)的相似性为97.3%。功能结构域分析显示其编码区包含信号肽、催化区、Ⅲ型粘蛋白同源区及几丁质结合区4个部分。更多还原

【Abstract】 Based on the conserved 5’ and 3’ sequence of chitinase gene from B.thuringiensis,a product of 2 031 bp was amplified and cloned into Escherichia coli strain DH5α from B.thuringiensis serovar entomocidus strain HD109 genomic DNA.The product encoded an open reading frame (chiA74-HD109) encoding a deduced protein of 676 amino acids.Removal of the signal peptide sequence resulted in a predicted protein that was 70 457 Da in size and 5.45 of isoelectric point.The deduced 676 amino acids sequence showed high degree of identity with other chitinases such as ChiB(AB041932) from Bacillus cereus(97.9 %),chiA74(AF424979) from B.thuringiensis serovar kenyae strain LBIT-82(98.4 %),chitinase(U89796) from B.thuringiensis serovar pakistani(83.0 %),kchi(AY189740) from B.thuringiensis serovar kurstaki(97.8 %),chitinase(AF526379) from B.thuringiensis serovar israelensis(96.6 %),chitinase(AY074882) from B.thuringiensis(98.4 %),and chitinase(AY129671) from B.thuringiensis serovar sotto(97.3 %).Analysis of the sequence indicated that the chitinase contained a catalytic domain belonging to family 18 of glycosyl hydrolases in the N-terminus,a fibronectin type Ⅲ domain in the middle region and a chitin-binding domain in the C-terminus.All three domains showed conserved sequences when compared to other bacterial chitinase sequences.更多还原