CSGA EXPRESSION ENTRAINS MYXOCOCCUS-XANTHUS DEVELOPMENT
CSGA EXPRESSION ENTRAINS MYXOCOCCUS-XANTHUS DEVELOPMENT
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DOI：
10.1101/gad.6.3.401
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发表时间：
1992-03-01
影响因子：
10.5
通讯作者：
SHIMKETS, LJ
中科院分区：
文献类型：
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作者：
LI, SF;LEE, BU;SHIMKETS, LJ
粘细菌粘球菌Xanthus的发育周期由三个部分重叠的形态学阶段组成，称为波纹，子实体形成和孢子形成，所有这些都不存在于csgA无效突变体中。CsgA基因产物是细胞外蛋白，称为C信号，其对于发育细胞-细胞相互作用是必需的。csgA表达在整个发育过程中增加，在孢子形成期间达到峰值。通过构建csgA基因上游的巢式缺失使CsgA限制发育，这导致csgA表达减少。连续较大的缺失导致终止的发展在较早和较早的阶段，与涟漪需要约20%的最大csgA的表达，子实体形成需要约30%的表达，孢子形成需要82%的表达。相反，人工诱导csgA也诱导发育提供营养物质是有限的。这些结果表明，稳定增加CsgA在发展过程中夹带的自然序列的形态学事件。csgA上游区域似乎处理关于营养物、肽聚糖组分和B信号水平的信息。在营养物质的情况下，从转录起始位点向上游延伸400 bp的区域是发展和最大csgA表达所必需的。在低水平的营养物质的存在下，一个区域延伸约930 bp的上游是必不可少的相同的任务。从-400到-930延伸的上游区域似乎在过量的碳、氮和磷酸盐存在下刺激csgA表达，从而允许发育完成。
The developmental cycle of the myxobacterium Myxococcus xanthus consists of three partially overlapping morphological stages referred to as rippling, fruiting body formation, and sporulation, all of which are absent in csgA null mutants. The CsgA gene product is an extracellular protein, referred to as the C signal, which is essential for developmental cell-cell interactions. csgA expression increases throughout development, reaching its peak during sporulation. CsgA was made limiting for development by constructing nested deletions upstream from the csgA gene, which resulted in reduced csgA expression. Successively larger deletions resulted in termination of development at earlier and earlier stages, with rippling requiring approximately 20% maximum csgA expression, fruiting body formation requiring approximately 30% expression, and sporulation requiring 82% expression. Conversely, artificial induction of csgA also induced development provided nutrients were limiting. These results suggest that steady increases in CsgA over the course of development entrain the natural sequence of morphological events. The csgA upstream region appears to process information concerning the levels of nutrients, peptidoglycan components, and the B signal. In the absence of nutrients, a region extending 400 bp upstream from the start site of transcription was necessary for development and maximal csgA expression. In the presence of low levels of nutrients, a region extending approximately 930 bp upstream was essential for the same tasks. It appears that the upstream region extending from -400 to -930 stimulates csgA expression in the presence of excess carbon, nitrogen, and phosphate, thereby allowing development to go to completion.