Tisa L S, Adler J
Department of Biochemistry, University of Wisconsin, Madison 53706.
Proc Natl Acad Sci U S A. 1992 Dec 15;89(24):11804-8. doi: 10.1073/pnas.89.24.11804.
Escherichia coli regulates intracellular free Ca2+ at about 90 nM [Gangola, P. & Rosen, B. P. (1987) J. Biol. Chem. 262, 12570-12574]. To increase intracellular free Ca2+, nitr-5/Ca2+, a "caged" Ca2+ compound, was electroporated into cells and then its affinity for Ca2+ was reduced by exposure to 370-nm light. Upon release of the Ca2+ ions, the cells tumbled. Studies on mutant strains showed that the receptor proteins (methyl-accepting chemotaxis proteins, MCPs) were not required for the Ca(2+)-induced tumbling but that CheA, CheW, and CheY proteins were required. Similar results were obtained with DM-nitrophen/Ca2+, another caged calcium compound that releases Ca2+ upon illumination at 340 nm. Diazo-2, a caged Ca2+ chelator that takes up Ca2+ upon illumination at 340 nm, was used to decrease intracellular free Ca2+, and this caused smooth swimming.
大肠杆菌将细胞内游离钙离子浓度调节在约90纳摩尔[甘戈拉，P. & 罗森，B. P.（1987年）《生物化学杂志》262卷，第12570 - 12574页]。为了增加细胞内游离钙离子浓度，“笼状”钙离子化合物硝普钠 - 5/钙离子通过电穿孔导入细胞，然后通过暴露于370纳米波长的光来降低其对钙离子的亲和力。钙离子释放后，细胞发生翻滚。对突变菌株的研究表明，钙离子诱导的翻滚不需要受体蛋白（甲基化趋化蛋白，MCPs），但需要CheA、CheW和CheY蛋白。用另一种笼状钙化合物二甲基硝基苯酚/钙离子（在340纳米光照下释放钙离子）也得到了类似结果。重氮 - 2是一种笼状钙离子螯合剂，在340纳米光照下摄取钙离子，用于降低细胞内游离钙离子浓度，这会导致细胞平稳游动。
