Chemotactic properties of Escherichia coli mutants having abnormal Ca2+ content.
Chemotactic properties of Escherichia coli mutants having abnormal Ca2+ content.
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Ca2 含量异常的大肠杆菌突变体的趋化特性。
DOI：
10.1128/jb.177.24.7112-7118.1995
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发表时间：
1995
影响因子：
3.2
通讯作者：
Adler,J
中科院分区：
文献类型：
--
作者：
Tisa,LS;Adler,J
已知大肠杆菌的calA、calC和calD突变体对Ca 2+敏感（R. N.布雷和B。P.罗森，细菌学杂志。139：824-834，1979）。在没有任何额外的趋化性刺激的情况下，calC和calD突变体都以翻滚的偏向游泳。通过计算机分析、使用群板和毛细管测定，calC和calD突变体在趋化性方面都有缺陷。calA突变体的运动只有轻微的缺陷，只有轻微的趋化性受损。化学活性野生型细胞具有约105 nM的细胞内游离Ca 2+水平。如通过使用荧光Ca 2+指示剂染料fura-2或fluo-3测定的，突变体的细胞内游离Ca 2+水平对于calA、calC和calD分别为约90、约1，130和约410 nM。降低野生型细胞和tumbly cal突变体中的细胞内游离Ca 2+水平，通过使用Ca 2+螯合剂促进跑步（平滑游泳）。在野生型和tumbly cal突变体中过表达CheZ（导致CheY-磷酸的去磷酸化）降低了tumbliness（由CheY-磷酸引起）的水平。calA突变体比野生型对ω-芋螺毒素对趋化性的抑制作用的抗性高4至10倍。ω-芋螺毒素对野生型E.该结果表明ω-芋螺毒素在入口点而不是出口点影响Ca 2+转运。
The calA, calC, and calD mutants of Escherichia coli are known to be sensitive to Ca2+ (R. N. Brey and B. P. Rosen, J. Bacteriol. 139:824-834, 1979). In the absence of any added stimuli for chemotaxis, both the calC and the calD mutants swam with a tumbly bias. Both the calC and the calD mutants were defective in chemotaxis as measured by computer analysis, use of swarm plates, and capillary assays. The calA mutant was only slightly defective in motility and only slightly impaired in chemotaxis. Chemotactically wild-type cells had an intra-cellular free-Ca2+ level of about 105 nM. The intracellular free-Ca2+ levels of the mutants, as determined by use of the fluorescent Ca2+ indicator dye fura-2 or fluo-3, were about 90, about 1,130, and about 410 nM for calA, calC, and calD, respectively. Lowering the intracellular free-Ca2+ levels in wild-type cells and in the tumbly cal mutants by use of Ca2+ chelators promoted running (smooth swimming). Overexpression of CheZ (which causes dephosphorylation of CheY-phosphate) in the wild type and in the tumbly cal mutants decreased the level of tumbliness (which is caused by CheY-phosphate). The calA mutant was 4- to 10-fold more resistant than the wild type to the inhibitory effect of omega-conotoxin on chemotaxis. omega-Conotoxin had no effect on Ca2+ extrusion by wild-type E. coli; that result suggests that omega-conotoxin affects Ca2+ transport at the point of entry instead of exit.