Membrane Complexes Required for Gliding Motility.

滑动运动所需的膜复合物。

• 批准号: 0094635
• 负责人: Patricia Hartzell
• 金额: $ 36.32万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0094635&HistoricalAwards=false
• 关键词: Membrane; Complexes; Required; Gliding; Motility.

0094635HartzellStudies of the soil-dwelling bacterium Myxococcus xanthus have broadened our understanding of prokaryotic biology. M. xanthus uses gliding motility to forage for nutrients in relatively dry environments and to form a fruiting body containing quiescent spores in the absence of nutrients. We have discovered independent sets of genes encoding homologs of the E. coli transmembrane TolBQRA protein complex that are essential for gliding motility during growth. Surprisingly, the Tol proteins are not needed for gliding per se during development, because disruption of any of the tol genes does not affect aggregation or fruiting body formation. However, the spores produced by tol mutants fail to mature, showing that the Tol proteins are required at a late stage of spore differentiation. We will test the hypothesis that the Tol proteins are involved in the transport of biopolymers needed for gliding motility during growth and spore maturation during development. Important clues to the function of the Tol complex have come from the study of one tol operon, the gidA- aglU (tolB1) operon. AglU, a homolog of TolB, is predicted to be an outer membrane lipoprotein. Like TolB, AglU contains WD-repeat motifs that form B-propellar structures that mediate protein-protein interactions with the TolQRA proteins located in the inner membrane. The gidA gene encodes a homolog of the E. coli glucose-inhibited division protein, a protein of unknown function present in many prokaryotes. Purified M. xanthus GidA absorbs at 450nm and has features showing that it is a flavoprotein. The gidA mutant does not aggregate and cells do not differentiate into spores. Moreover, the gidA mutant releases a substance that inhibits the development of wild-type cells. The inhibitor is likely exported via the Tol complex, because a second mutation in aglU prevents the release of this toxic substance. Analysis of the inhibitor, purified from the gidA mutant, may provide clues to the nature of the material secreted through the Tol complex.

0094635 Hartzell对土壤细菌粘球菌的研究拓宽了我们对原核生物学的理解。 M.在相对干燥的环境中，黄属利用滑动运动来寻找营养，并在缺乏营养的情况下形成含有静止孢子的子实体。 我们已经发现了编码E.大肠杆菌跨膜TolBQRA蛋白复合物是生长过程中滑行运动所必需的。 令人惊讶的是，Tol蛋白本身在发育过程中并不需要滑行，因为任何tol基因的破坏都不会影响聚集或子实体的形成。 然而，由tol突变体产生的孢子不能成熟，表明在孢子分化的后期阶段需要Tol蛋白。 我们将测试的假设，Tol蛋白参与运输的生物聚合物需要滑行运动在生长过程中和孢子成熟过程中的发展。 Tol复合物功能的重要线索来自对一种tol操纵子gidA-aglU（tolB 1）操纵子的研究. TolB的同源物AglU被预测为外膜脂蛋白。 与TolB一样，AglU含有WD重复基序，其形成B-螺旋结构，介导与位于内膜中的TolQRA蛋白的蛋白质-蛋白质相互作用。 gidA基因编码E.大肠杆菌葡萄糖抑制分裂蛋白，一种存在于许多原核生物中的功能未知的蛋白。 纯化的M. xanthus GidA在450 nm处有吸收，其特征表明它是一种黄素蛋白。gidA突变体不聚集，细胞不分化成孢子。 此外，gidA突变体释放出一种抑制野生型细胞发育的物质。 抑制剂可能通过Tol复合物输出，因为aglU中的第二个突变阻止了这种有毒物质的释放。 从gidA突变体中纯化的抑制剂的分析可以提供通过Tol复合物分泌的物质的性质的线索。