INVESTIGATIONS OF DYNAMICS AND FUNCTIONAL DIVERSITIES OF LYSINE 5,6-AMINOMUTASE

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 本文利用小角X射线散射研究底物诱导的赖氨酸5，6-氨基变位酶（5，6-LAM）构象变化。5，6-LAM是一种腺苷钴胺素（Adenosylcobalamin，缩写为B1, 2）和吡哆醛5 <$-磷酸（PLP，缩写为B6）依赖性α 2 β 2四聚体，可催化D-或L-赖氨酸和L-β-赖氨酸末端氨基的不寻常、可逆的1，2-重排。Cbl是自由基化学反应中的重要辅因子。载脂蛋白-5，6-LAM的晶体结构表明，底物结合可能诱导大的构象变化，以使apoCbl靠近活性位点中的底物和PLP。我们建议使用SAXS检查（i）辅因子的作用;（ii）所提出的底物诱导的构象变化;和（iii）通过关联催化活性，底物特异性和所提出的构象变化来研究5，6-LAM的功能-结构关系。此外，连接5，6-LAM的二聚化和催化结构域的高度无序区域由晶体结构揭示，并且将研究高度无序区域和二聚化结构域在所提出的构象变化和酶的催化活性/底物特异性中的作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We propose to use small-angle x-ray scattering to investigate substrate-induced conformational change of lysine 5,6-aminomutase (5,6-LAM). 5,6-LAM is an adenosylcobalamin (AdoCbl, or coenzyme B12)- and pyridoxal 5¿-phosphate (PLP, coenzyme B6)-dependent alpha2beta2 tetramer that catalyzes an unusual, reversible, 1,2-rearrangement of the terminal amino group of D- or L-lysine and of L-beta-lysine. AdoCbl is an important cofactor in free radical chemistry reactions. The crystal structure of the apo-5,6-LAM suggests that substrate binding likely induces a large conformational change to place AdoCbl close to both the substrate and PLP in the active site. We propose to use SAXS to examine (i) the role(s) of cofactors; (ii) the proposed substrate-induced conformational change; and (iii) the function-structure relationship of 5,6-LAM by correlating catalytic activity, substrate specificity, and the proposed conformational change. In addition, a highly disordered region connecting the dimerization and catalytic domains of 5,6-LAM is revealed by the crystal structure, and the role(s) of the highly disordered region and the dimerization domain in the proposed conformational change and in the catalytic activity/substrate specificity of the enzyme will be investigated.