Genetics, Mechanism and Regulation of Cellulose Synthesis inA. Tumefaciens

9405844 Matthysse建议继续研究A.根瘤菌 在以前的研究中，纤维素合成所需的两个操纵子被鉴定和测序。 在相同的研究中，还开发了体外纤维素合成系统。 有了这种体外纤维素合成系统，再加上突变细胞中的cel（纤维素合成）基因，每一个cel基因产物在纤维素合成中的作用就变得更加复杂。 可以确定形成。 通过使用相同的纤维素合成系统和突变体收集，发现了纤维素合成的可能中间体，并确定了这些中间体的化学结构。 此外，还对A.在植物细胞或植物提取物的存在下，根癌农杆菌的数量增加。 将审查这一规定的机制。 纤维素是由植物、细菌和真菌产生的，是地球上最丰富的生物材料之一。 它是一种相对简单的分子，由β-1，4-葡萄糖分子的线性链组成。 然而，纤维素合成的详细机制还不清楚。 目前尚不清楚是否所有的生物体都使用类似的途径来制造纤维素，或者是否有不同的生物体使用不同的途径。 纤维素合成的调控也知之甚少。 在本研究项目中，将检查称为根癌农杆菌的细菌合成纤维素的机制和调节。 使用细菌研究纤维素合成的优点是细菌相对简单，并且通常更容易确定所需的基因以及相同基因产物在复杂生物合成途径中的单独作用。 在早期的研究中，确定了这种细菌形成纤维素的基因。 现在，随着突变细胞的收集和无细胞纤维素合成系统的开发，人们希望可以确定纤维素合成的每一个基因的功能，纤维素形成途径中的化学步骤将被确定，并且可以进行实验以开始了解微生物途径是如何调节纤维素形成的。 ***

9405844 Matthysse It was propose to continue our investigation of the mechanisms of cellulose synthesis by A. tumefaciens. In previous research, two operons required for cellulose synthesis were identified and sequenced. In the same studies, an in vitro cellulose synthesis system was also developed. With this in vitro cellulose synthesis system together with mutant cells in the cel (cellulose synthesis) genes, the role of each one of the cel gene products in cellulose formation may be determined. By using the same in vitro cellulose synthesis system and mutant collection, putative intermediates in cellulose synthesis were found. The chemical structure of these intermediates will be determined. In addition, cellulose synthesis in A. tumefaciens is increased in the present of plant cells or plant extracts. The mechanism of this regulation will be examined. %%% Cellulose, which is made by plants and by some bacteria and fungi, is one of the most abundant biologically produced materials on earth. It is a relatively simple molecule consisting of a linear chain of beta-1,4-glucose molecules. However, the detailed mechanism of cellulose synthesis is not well understood. It is not now known whether all organisms which make cellulose use similar pathways, or whether there are different pathways used by different groups of organisms. The regulation of cellulose synthesis is also poorly understood. In this research project, the mechanism and regulation of cellulose synthesis by a bacterium called Agrobacterium tumefaciens will be examined. The advantages of using a bacterium to study cellulose synthesis are that the bacteria are relatively simple and often allow more easily for the determination of genes required and the individual role(s) of the same gene products in a complex biosynthetic pathway. In an earlier study, the genes for cellulose formation by this bacterium were determined. Now with a collection of mutant cells and the development of a cell-fre e cellulose synthesis system, it is hoped that the function of each one of the genes of cellulose synthesis can be determined, that the chemical steps in the pathway for cellulose formation will be identified, and that experiments can be undertaken to begin to understand how the microbial pathway is regulated for cellulose formation. ***