Envelope Components of Gliding Bacteria

许多细菌能够在固体表面（通常是生物聚合物，如琼脂、纤维素、几丁质、果胶或木聚糖）上移动，这一过程被称为滑翔。这是这些生物在矿化过程中发挥核心作用的一个重要方面，许多“高等”生命形式无法影响矿化过程，但它们依赖矿化过程。滑翔细菌完成这种易位的机制仍然是个谜；然而，在这个实验室中首次分离和描述的磺胺脂是第一个被认为是滑翔运动所必需的分子（在细胞吞噬体和柔韧性细菌中）。细胞表面的多糖也起辅助作用。当前关注的细胞包膜特征在细胞易位中很重要，包括肽聚糖相关蛋白和其他细胞包膜特征，当特定的非滑移突变体可逆地恢复滑行能力时，这些特征会发生变化。细菌如何滑翔一直是微生物学中最棘手的问题之一。没有关于滑翔机制的形态学线索。许多实验室多年来一直在研究这个问题，使用遗传和生化方法，但收效甚微。Leadbetter实验室有了突破性的发现，他们发现了一种特殊的非利格突变体jonsonae在一种新型磺类脂的生物合成途径中存在缺陷，并且可以通过在培养基中添加适当的代谢前体（半胱氨酸）来逆转非利格表型。这个项目是对这一开创性发现的生化后续研究，并有望真正破译参与滑翔机制的细菌分子的本质。

Many bacteria are able to move over solid surfaces (often these are biological polymers such as agar, cellulose, chitin, pectin, or xylan) by a process termed gliding. This is an important aspect of these organisms' central role in the mineralization processes which so many "higher" forms of life are unable to effect, but upon which they are dependent. The mechanism by which the gliding bacteria accomplish this translocation remains a mystery; however, the sulfonolipids first isolated and described in this laboratory are the first molecules to be recognized as necessary (in the cytophagas an flexibacters) for gliding motility. A cell-surface polysaccharide also plays an accessory role. The current focus on the features of the cell envelope that are important in cell translocation will include a peptidoglycan-associated protein and other cell envelope features that change when a particular nongliding mutant regains, reversibly, the ability to glide. %%% The question of how gliding bacteria glide has been one of the most intractable problems in microbiology. There are no morphological clues to the mechanism of gliding. A number of laboratories have been working on the problem for many years, using both genetic and biochemical approaches, with minimal success. The Leadbetter laboratory made a breakthrough discovery when it was found that a particular nongliding mutant of Cytophaga johnsonae had a defect in the pathway of biosynthesis of a novel sulfonolipid, and that the nongliding phenotype could be reversed by the addition of the appropriate metabolic precursor (cysteate) to the culture medium. This project is a biochemical followup to that seminal discovery, and holds the promise of actually deciphering the nature of the bacterial molecule(s) involved in the gliding mechanism.