Gomes S L, Shapiro L
J Mol Biol. 1984 Sep 25;178(3):551-68. doi: 10.1016/0022-2836(84)90238-9.
Proteins involved in chemotaxis methylation reactions have been identified in Caulobacter crescentus and their activities, times of synthesis and cellular positions have been determined. The methyl-accepting chemotaxis proteins, the methyl-transferase and the methylesterase were all shown to be active in the flagella-bearing swarmer cell, but all three activities were lost after the swarmer cells shed their flagellum and differentiated into a stalked cell. The membrane methyl-accepting chemotaxis proteins were shown to be synthesized before cell division, coincident with the synthesis of the components of the flagellum, and to be specifically localized in the membrane of the incipient swarmer cell portion of the predivisional cell. The cytoplasmic methylesterase was also found to be differentially synthesized coincident with the period of flagellar biogenesis. Furthermore, methyltransferase activity, present in the predivisional cell, was detected only in the swarmer cell upon cell division. These results demonstrate that the chemotaxis methylation machinery is positionally biased toward one portion of the predivisional cell, and that the time of expression of a set of fla and che genes is correlated with the positioning of their gene products within the cell.
在新月柄杆菌中已鉴定出参与趋化作用甲基化反应的蛋白质，并确定了它们的活性、合成时间和细胞定位。甲基接受趋化蛋白、甲基转移酶和甲基酯酶在带有鞭毛的游动细胞中均表现出活性，但在游动细胞脱落鞭毛并分化为柄细胞后，这三种活性均丧失。膜甲基接受趋化蛋白在细胞分裂前合成，与鞭毛成分的合成同时发生，并特异性定位于分裂前细胞初始游动细胞部分的膜中。还发现细胞质甲基酯酶在鞭毛生物发生期间差异合成。此外，存在于分裂前细胞中的甲基转移酶活性仅在细胞分裂后的游动细胞中检测到。这些结果表明，趋化作用甲基化机制在位置上偏向于分裂前细胞的一部分，并且一组鞭毛（fla）和趋化（che）基因的表达时间与其基因产物在细胞内的定位相关。
