Gene Enzyme and Physiological Characterization of shrunken-2Isoalleles

9316887汉娜：腺苷二磷酸葡萄糖焦磷酸化酶的变构性质对控制从大肠杆菌到土豆的各种生物中葡萄糖聚合物的含量至关重要。玉米转座元件，解离DS，被放置在编码玉米胚乳酶基因的编码区。DS切除是不精确的，因此逆转基因代表了一系列密切相关的突变，这些突变来自基因中的一个位置。这种体内、定点突变的形式被用来创造在DNA序列、酶水平、变构性质和种子重量上不同的野生型变异。由于淀粉占种子重量的70%，淀粉含量很可能发生了变化。这项研究将进一步在DNA、酶和生理水平上对逆转株进行表征。其他切除事件将识别该位置的变化，不仅恢复基因功能，而且那些不恢复基因功能的变化。整合基因、酶和生理水平的研究将有助于确定关键酶的一个重要区域的结构/功能关系，以及这些变化如何影响淀粉含量。其次，这些研究为研究DS易位的机制提供了新的视角。出乎意料的是，一些反转体并不容易适应当前的转位模型。额外的删减事件应导致现有模型的修改或新模型的开发。综上所述，为了更清楚地了解该酶的这一区域如何影响其变构性质，以及反过来，变化如何影响淀粉的生物合成，提出了一系列综合实验。除此之外，人们还将更好地理解D是如何起诱变剂作用的。***

9316887 Hannah The allosteric properties of ADP-glucose pyrophosphorylase are critical in controlling the amount of glucose polymers in organisms ranging from E. coli to potato. The maize transposable element, dissociation Ds, was placed within the coding region of the site of a gene encoding the maize endosperm enzyme. Ds excisions are imprecise, thus revertants represent a series of closely-related mutations arising from one position in the gene. This form of in- vivo, site-specific mutagenesis was used to create wild type variants that differ in DNA sequence, enzyme levels, allosteric properties and seed weight. Since starch comprises 70% of seed weight, starch content likely has been altered. This research will further characterize revertants at DNA, enzyme and physiological levels. Additional excision events will identify changes at this site not only restoring gene function, but those not restoring gene function. Integration of studies at the gene, enzyme and physiological levels of the isogenic maize lines will help define the structure/function relationships of a important region of a critical enzyme and how these changes affect starch content. Secondly, these studies are providing new insight into the mechanism of Ds transposition. Unexpectedly some revertants do not easily fit current models of transposition. Additional excision events should lead to modification of existing models or to development of new ones. In summary, a series of integrated experiments are proposed to more clearly understand how this region of the enzyme affects its allosteric properties and, in turn, how changes affect starch biosynthesis. Coupled with this will be a better understanding of how Ds acts as a mutagen. ***