INTERPRETING CONFORMATIONAL DIFFERENCES IN THE ALLOSTERIC REGULATION OF PYRUV

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， 因此可以在其他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。 我们建议使用X-射线晶体学来研究变构蛋白质，兔肌肉丙酮酸激酶（M1-PYK）的构象变化是重要的变构机制。 尽管变构调节在允许生物系统适应变化的环境中的重要性，但对变构的分子机制知之甚少。 我们对M1-PYK的变构效应物的结果表明，抑制剂苯丙氨酸内的离散亚结构具有功能特异性作用，即，结合所需的亚结构不同于引发变构反应的亚结构（威廉姆斯等人（2006）生物化学45，5421-5429）。 由此产生的假设是，效应子结合后改变的蛋白质性质也必须分为相同的功能子集。使用该信息，丝氨酸和丙氨酸可以被认为是非变构效应类似物，即与苯丙氨酸竞争性结合但不引起变构应答的类似物。 2-与苯丙氨酸相比，氨基丁酸具有适度的变构抑制作用。 小角X-射线散射数据表明，苯丙氨酸结合时观察到的全局构象变化也引起非变构效应类似物结合时。因此，这些全局变化可能仅限于绑定功能。 需要比SAXS更高分辨率的数据来表征不同效应类似物引起的变化之间的微小差异。 这些微小的差异可能是变构功能的结果。 我们先前已经解析了与Ala复合的M1-PYK在1.65 Ω处的结构（威廉姆斯等人（2006）生物化学45，5421-5429）。 当前的射束时间请求将用于收集与苯丙氨酸、2-氨基丁酸和丝氨酸共结晶的M1-PYK结构的数据。

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 X-ray crystallography to study conformational changes of an allosteric protein, rabbit muscle pyruvate kinase (M1-PYK) that are important to the allosteric mechanism. Despite the importance of allosteric regulation in allowing biological systems to adapt to changing environments, the molecular mechanisms of allostery are poorly understood. Our results with allosteric effectors of M1-PYK demonstrate that discrete substructures within the inhibitor, phenylalanine, have functionally specific roles, that is, substructures required for binding differ from those that elicit an allosteric response (Williams et al. (2006) Biochemistry 45, 5421-5429). The resulting hypothesis is that the protein properties that are altered upon effector binding must also be divided into the same functional subsets. Using this information, serine and alanine can be considered as non-allosteric effector analogs, analogs that bind competitively with phenylalanine but do not elicit an allosteric response. 2-amino butyric acid elicits a modest allosteric inhibition as compared to phenylalanine. Small-angle X-ray scattering data indicate that the global conformational changes observed when phenylalanine binds are also elicited when non-allosteric effector analogs bind. As such, these global changes may be confined to binding functions. Higher resolution data than are possible with SAXS are needed to characterize small differences between the changes elicited by different effector analogs. These small differences are likely consequential to allosteric functions. We have previously solved the structure of M1-PYK in complex with Ala at 1.65¿ (Williams et al. (2006) Biochemistry 45, 5421-5429). The current beamtime request will be used to collect data for the structures of M1-PYK co-crystalized with phenylalanine, 2-amino butyric acid, and serine.