Study of cell wall permeability of bacteria from the order Actinomycetales with special emphasis on structure and function of cell wall channels

革兰氏阳性细菌（包括放线菌目细菌）的细胞壁被认为对小的亲水性溶质具有自由渗透性。几年前，我们能够证明在革兰氏阳性分枝杆菌（棒状杆菌亚科或棒状杆菌）的两个成员龟分枝杆菌和耻垢分枝杆菌的细胞壁中存在通道（Trias等人，一九九二年; Benz和Trias，1993; 1994），这些细胞壁通道将分枝菌的分枝菌酸层定义为渗透性屏障，并表明其与革兰氏阴性细菌的外膜具有某些相似性。细胞壁通道在真菌生理学中的作用现在被广泛接受。一个仍然悬而未决的问题是它们在不含分枝菌酸的分枝菌门亲属中的作用。该项目将涉及分枝菌细胞壁通道的翻译、结构和组装，特别强调对不同棒杆菌属物种的研究，例如能够以技术规模生产氨基酸的谷氨酸棒杆菌、Callunae棒杆菌和Corynebacterium efficiens棒杆菌。特别令人感兴趣的是不同细胞壁通道蛋白PorA/H/B/C在细胞壁的渗透性中的作用以及改变通道的渗透性的蛋白质突变。对其他革兰氏阳性菌（属于放线菌目）细胞壁通道的研究也将继续进行。特别令人感兴趣的是不含分枝菌酸的细菌细胞壁的渗透性性质的定义，例如来自链霉菌属和棒状杆菌属的物种。这里，形成渗透性屏障的脂质的结构应当被阐明和表征。这些细菌细胞壁通道的一级结构是绝对未知的。通道形成蛋白的基因将被克隆和测序。将尝试使来自不同生物体的细胞壁通道结晶。

The cell walls of gram-positive bacteria including those from the order Actinomycetales were believed to be freely permeable to small hydrophilic solutes. Several years ago we were able to demonstrate the presence of channels in the cell walls of two members of the grampositive mycolata (suborder Corynebacteriaceae or Coryneform bacteria), Mycobactehum chelonae and Mycobacterium smegmatis (Trias et al., 1992; Benz and Trias, 1993; 1994), These cell wall channels define the mycolic acid layer of the mycolata as a permeability barrier and suggest that it shares certain similarities to the outer membrane of gram-negative bacteria. The role of cell wall channels in the physiology of the mycolata is now widely accepted. A still open question is their role in non-mycolic acid containing relatives of mycolata. The project will deal with the translation, structure and assembly of cell wall channels of mycolata with special emphasis on the investigation of those of different Corynebacterium species, such as Corynebacterium glutamicum, Corynebacterium callunae and Corynebacterium efficiens that are able to produce amino acids at a technical scale. Of particular interest is the role of the different cell wall channel proteins PorA/H/B/C in the permeability properties of the cell wall and mutations of the proteins to alter the permeability properties of the channels. The study of the cell wall channels from other gram-positive bacteria, which belong to the order Actinomycetales will also be continued. Of special interest is the definition of the permeability properties of the cell wall of bacteria that that do not contain mycolic acids, such as species from the genera Streptomycetes and Corynebacterium, Here the structure of the lipids that form the permeability barrier should be elucidated and characterized. The primary structure of the cell wall channels of these bacteria is absolutely unknown. The genes of the channel-forming proteins will be cloned and sequenced. Attempts will be made to crystallize cell wall channels from different organisms.