CAULOBACTER FLAGELLAR FUNCTION, BUT NOT ASSEMBLY, REQUIRES FLIL, A NON-POLARLY LOCALIZED MEMBRANE-PROTEIN PRESENT IN ALL CELL-TYPES
CAULOBACTER FLAGELLAR FUNCTION, BUT NOT ASSEMBLY, REQUIRES FLIL, A NON-POLARLY LOCALIZED MEMBRANE-PROTEIN PRESENT IN ALL CELL-TYPES
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DOI：
10.1006/jmbi.1994.1650
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发表时间：
1994-10-21
影响因子：
5.6
通讯作者：
SHAPIRO, L
中科院分区：
文献类型：
--
作者：
JENAL, U;WHITE, J;SHAPIRO, L
新月茎杆菌具有单极鞭毛，在分裂前细胞中组装。已知的鞭毛基因编码鞭毛组装和功能所需的结构和调控成分。这些基因被组织成几类，形成一个转录调控层次结构。II类基因的一个成员，FliM操纵子，编码大肠杆菌鞭毛开关蛋白的同源物：FliM；以及一种功能未知的蛋白质FliL。我们在这里报道鞭毛旋转需要FliL蛋白。fliL基因染色体拷贝的框架内缺失导致细胞形成鞭毛，但不能运动。FliL蛋白被发现与细胞膜有关，并存在于所有类型的细胞中。这是首次报道一种对运动至关重要但不局限于鞭毛基体区域的新月茎杆菌蛋白。虽然FliL是鞭毛功能所必需的，但它不是转录层次结构的一部分，这支持了这样的假设，即与肠道的情况一样，调控层次结构与组装线索有关，而不是直接与鞭毛蛋白的表达有关。
Caulobacter crescentus has a single polar flagellum, which is assembled in the predivisional cell. Known flagellar genes encode structural and regulatory components that are required for flagellar assembly and function. These genes are organized in several classes which form a transcriptional regulatory hierarchy. A member of the Class II genes, the fliLM operon, encodes homologs of the Escherchia coli flagellar switch protein: FliM; and a protein with a hitherto unknown function, FliL. We report here that flagellar rotation requires the FliL protein. In-frame deletions in the chromosomal copy of the fliL gene result in cells that form a flagellum but are non-motile. The FliL protein was found to be associated with the inner membrane and to be present in all cell types. This is the first report of a Caulobacter crescentus protein that is essential for motility but is not spatially restricted to the region of the flagellar basal body. Although FliL is required for flagellar function, it is not part of the transcriptional hierarchy, supporting the hypothesis that, as is the case for the enterics, the regulatory hierarchy resp ends to assembly cues rather than directly to the expression of flagellar proteins.