Conversion of Inactive Cobalamins to Coenzyme B12

无活性钴胺素转化为辅酶 B12

• 批准号: 6803162
• 负责人: THOMAS Aquinas BOBIK
• 金额: $ 20.6万
• 依托单位: IOWA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6803162
• 关键词: Escherichia coli; alkyltransferase; bacterial genetics; bacterial proteins; biotechnology; cobalamin; enzyme induction /repression; enzyme mechanism; genetic mapping; methionine; microorganism metabolism; miscellaneous oxidoreductase; nutrition related tag; transfection /expression vector; vitamin B12 coenzyme; vitamin metabolism

DESCRIPTION (provided by applicant): Coenzyme B12-dependent processes are vital to human health and play important roles in ecological niches and industrial applications. The long-term goal of the proposed research is to improve our general understanding of the genetics and biochemistry of coenzyme B 12. The proposed studies focus on the metabolism of inactive cobalamins into the B 12 coenzymes. This process is needed for the assimilation of exogenous cobalamins, and because the B 12 coenzymes are unstable, for the maintenance of adequate B 12 pools to meet physiological needs. The human cob(I)alamin adenosyltransferase which functions in cobalamin metabolism will be characterized biochemically and its 3-dimensional structure will be determined. The reduction of cob(II) alamin to cob(I)alamin for coenzyme B 12 synthesis will also be investigated. Preliminary studies showed that the human methionine synthase reductase can reduce cob(II)alamin to cob(I)alamin for coenzyme B 12 synthesis, and results indicated a highly specific interaction between the human methionine synthase reductase and adenosyltransferase enzymes. The reduction of cob(II)alamin to cob(I)alamin by the human methionine synthase reductase will be more fully characterized. The results of bioinformatic analyses have indicated that the bacterial YgfD protein and its homologues are involved in cobalamin metabolism The specific function of the YgfD protein will be determined by a series of biochemical tests. The final aim of the project will be to use the genes identified in this study to construct gene therapy vectors for expression of enzymes involved in cobalamin metabolism. The proposed studies will provide information directly applicable to improved methods of diagnosis and treatment of inherited diseases of B 12 metabolism. Furthermore, since changes in B 12 metabolism have been linked to chronic liver disease, cancer, elevated serum homocysteine (a possible risk factor in heart disease), increased rates of DNA damage, impaired cognitive function, and HIV infection, the proposed studies may also provide information relevant to understanding these diseases.

描述（申请人提供）：辅酶B12依赖性过程对人类健康至关重要，在生态环境和工业应用中发挥重要作用。拟议研究的长期目标是提高我们对辅酶B 12的遗传学和生物化学的总体理解。拟议的研究集中在非活性钴酸盐代谢成B 12辅酶。这一过程对于外源性钴的同化是必需的，并且由于B 12辅酶不稳定，因此需要维持足够的B 12库以满足生理需要。将对在钴胺素代谢中起作用的人钴胺素腺苷转移酶进行生物化学表征，并确定其三维结构。还将研究用于辅酶B 12合成的co B（II）丙氨酸还原为co B（I）丙氨酸。初步研究表明，人甲硫氨酸合成酶还原酶可将辅酶B（II）丙氨酸还原为辅酶B（I）丙氨酸，用于辅酶B 12的合成，结果表明人甲硫氨酸合成酶还原酶和腺苷转移酶之间存在高度特异性的相互作用。通过人甲硫氨酸合酶还原酶将辅酶（II）三聚氰胺还原为辅酶（I）三聚氰胺将得到更充分的表征。生物信息学分析结果表明，细菌YgfD蛋白及其同源物参与了钴胺素的代谢。该项目的最终目的是利用本研究中鉴定的基因构建基因治疗载体，用于表达钴胺素代谢相关酶。拟议的研究将提供直接适用于改进B 12代谢遗传性疾病的诊断和治疗方法的信息。此外，由于B 12代谢的变化与慢性肝病、癌症、血清同型半胱氨酸升高（心脏病的一个可能的危险因素）、DNA损伤率增加、认知功能受损和HIV感染有关，因此拟议的研究也可能提供与理解这些疾病相关的信息。