TETHERED DOMAINS AS REGULATORY ELEMENTS

这项建议是为了研究3-3的监管机制- 磷酸甘油脱氢酶，一种致力于 丝氨酸生物合成。丝氨酸是一种负变构抑制物。 晶体结构表明调控位点在结构域中 与其他两个结构域分离，核苷酸和底物结合 域名。假设是核苷酸和氨基酸的结构域运动 底物结合域必须出现才能发生催化作用。 丝氨酸在调控部位的结合阻止了这种结构域的运动。 此外，丝氨酸在调节部位的结合增加了 两个监管站点之间的相互作用。初步实验 表明交叉链接相邻的监管结构域会导致 抑制，而定点突变实验削弱了 亚基之间的相互作用可防止丝氨酸的抑制作用。这 提案使用了各种荧光方法，并继续 确定变构机理的结晶学努力 控制力。

This proposal is to study the regulatory mechanism of 3- phosphoglycerate dehydrogenase, an enzyme that is the committed step in de novo serine biosynthesis. Serine is a negative allosteric inhibitor. The crystal structure indicates that the regulatory site is in a domain separated from other two domains, the nucleotide and substrate binding domains. The hypothesis is that a domain motion of the nucleotide and substrate binding domains has to occur for catalysis to take place. Binding of serine at the regulatory site prevents this domain motion. Further, the binding of serine at the regulatory site increases the interaction between two regulatory sites. Preliminary experiments indicate that cross-linking the adjacent regulatory domains results in inhibition, whereas site directed mutagenesis experiments weakening the interaction between subunits prevents inhibition by serine. This proposal uses a variety of fluorescence methodologies and continued crystallographic efforts to determine the mechanism of allosteric control.