MOLECULAR NOVELTY AND CONSERVATION IN BACTERIAL PROTEIN SEQUENCES

细菌蛋白质序列的分子新颖性和保守性

• 批准号: 3781269
• 负责人: J WOOTTON
• 金额: --
• 依托单位: NATIONAL LIBRARY OF MEDICINE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3781269
• 关键词: Archaea; Clostridium; Escherichia coli; Myxococcus; Streptomyces; active sites; bacterial proteins; biochemical evolution; computer assisted sequence analysis; enzyme mechanism; genome; glutamate dehydrogenase; photosynthetic bacteria; protein kinase; protein kinase C; protein sequence; protein structure function; protonation; site directed mutagenesis

Protein sequences deduced from gene sequences of diverse bacteria and archaebacteria are yielding a wealth of new knowledge on protein functions, interactions and evolution. Some novel findings were studied by concerted methods including directed mutagenesis, spectroscopic/enzymological analyses and computer analyses of sequence databases. Findings include:- A. Bacterial homologs of major "eukaryotic" protein families. Bacterial homologs of Serine/Threonine protein kinases were further investigated in cyanobacteria and archaebacteria. These are evidently relatively similar to the protein kinase C subfamily, but their phosphorylation specificity remains to be confirmed. B. Novel proton exchange mechanism in glutamate dehydrogenase. This enzyme differs from other NAD/NADP dependent dehydrogenases in lacking a catalytic histidine residue. From sequence conservation and site-directed mutagenesis of the E. coli enzyme, in comparison with the crystal structure of the Clostridium symbiosum enzyme, a triad of lysine residues was identified in the active site. These have novel protonation properties and evidently act in concert in dicarboxylate substrate binding, deprotonation of ammonium and other proton exchange steps of glutamate dehydrogenase catalysis. C. Sequence families in complex bacteria. New sequences from multicellular and differentiating bacteria, Streptomyces, Myxococcus and various cyanobacteria and archaebacteria, were investigated by global database sequence similarity searches. More than 50 percent of the classifiable protein sequences did not have counterparts in E. coli and other well-studied enteric bacteria, and many of these had eukaryotic homologs. Examples of low-complexity segments and multiple repeats are emerging with increasing frequency. Significance of project: Genome sequences from metabolically and morphogenetically diverse bacteria continue to provide a rich and cost-effective source of new discoveries on the molecular functions and evolution of proteins.

从不同细菌的基因序列推导的蛋白质序列 考古细菌正在产生有关蛋白质的大量新知识 功能，相互作用和进化。 研究了一些新颖的发现 通过包括定向诱变在内的协同方法， 光谱/酶学分析和序列的计算机分析 数据库。调查结果包括： - A.主要“真核”蛋白家族的细菌同源物。 丝氨酸/苏氨酸蛋白激酶的细菌同源物进一步 在蓝细菌和考古细菌中进行了研究。 这些显然是 与蛋白激酶C亚科相对相似，但 磷酸化特异性仍有待证实。 B.谷氨酸脱氢酶中的新型质子交换机制。 这 酶不同于其他NAD/NADP依赖性脱氢酶 催化组氨酸残基。 从序列保护和 与大肠杆菌酶的位置定向诱变相比 梭状芽胞杆菌酶的晶体结构，赖氨酸三合会 在活动部位确定了残留物。 这些有小说 质子化特性，显然在二羧酸盐中演奏 底物结合，铵和其他质子交换的去质子化 谷氨酸脱氢酶催化的步骤。 C.复杂细菌中的序列家族。 来自 多细胞和分化细菌，链霉菌，粘粘膜和 全球研究了各种蓝细菌和考古细菌 数据库序列相似性搜索。 超过50％ 可分类蛋白序列在大肠杆菌中没有对应物， 其他良好的肠细菌，其中许多都有真核的 同源物。 低复杂性段和多个重复的示例是 随着频率的增加而出现。 项目的意义：来自代谢和的基因组序列 形态学上多样的细菌继续提供丰富的 具有成本效益的分子功能新发现的来源和 蛋白质的进化。