嗜冷黄杆菌酰基-Acp去饱和酶(AAD)的序列分析和结构建模

Sequence analysis and structure modeling study of acyl-ACP desaturase from Flavobacterium psychrophilum

多不饱和脂肪酸是生物膜的重要组成成分,在维持细胞膜的流动性与低温适应性中起到重要作用。以低温微生物嗜冷黄杆菌为对象,主要采用多重序列比对、同源建模、模型评价等生物信息学技术与方法,分析与研究了多不饱和脂肪酸代谢重要相关蛋白酰基-Acp去饱和酶的序列组成与基序特征、系统进化与重要活性位点中心,模建并高评分地获得了其三维空间结构。系统发育分析表明,嗜冷黄杆菌等低温耐受菌与植物类物种的酰基-Acp去饱和酶的分子进化关系较近,而与其他细菌的分子进化关系较远。多序列基序分析显示,多数物种含有HxxxxH、HxxHH和HxxHH等3个组氨酸保守区,为二Fe离子结合区。Swiss-model对嗜冷黄杆菌的酰基-Acp去饱和酶进行的同源建模及其模型分析发现,其也具备与Fe离子相互作用的活性区,与Fe离子直接作用的活性位点有His114、Glu111、Glu76、His200、Glu19和Glu164,嗜冷黄杆菌的酰基-Acp去饱和酶有异于其它细菌的特异性。这从某种程度上揭示,相对于常温菌而言,低温耐受菌可能存在着低温相关蛋白酶的序列乃至功效上的差异。对于深入了解细菌耐低温机制,低温相关蛋白差异性分析及改造与应用均有重要的意义与价值。

Polyunsaturated fatty acids are important components of biofilms,which plays an important role in maintaining of membrane fluidity. In this paper,multiple sequence alignment,homology modeling,model evaluation and other bioinformatics methods were used to analyze the sequence composition,motifs characteristic,system evolution and important center of the active sites,as well as modeling and high score evaluation of the modelled three-dimensional structure of acyl-ACP desaturase in psychrophilic microorganism of Flavobacterium related to the metabolism of polyunsaturated fatty acids. Phylogenetic analysis showed that the molecular evolutionary relationship between Flavobacterium and plant species was closer than other bacteria. Multiple sequence motif analysis showed that the majority of species had three conserved histidine regions bonded to iron atoms. Homology modeling by Swiss-Model and model analysis of Flavobacterium acyl-ACP desaturase disclosed that it also had the active regions which could bond to iron atoms,and the active sites were composed of His114,Glu111,Glu76,His200,Glu19 and Glu164. The psychrophilic Flavobacterium acyl-ACP desaturase was quite different from other bacteria. Relative to normal temperature bacteria,the structure and function of low temperature resistant bacteria might be different.