Scharf B E, Fahrner K A, Berg H C
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
J Bacteriol. 1998 Oct;180(19):5123-8. doi: 10.1128/JB.180.19.5123-5128.1998.
The behaviors of both cheZ-deleted and wild-type cells of Escherichia coli were found to be very sensitive to the level of expression of CheZ, a protein known to accelerate the dephosphorylation of the response regulator CheY-phosphate (CheY-P). However, cells induced to run and tumble by the unphosphorylated mutant protein CheY13DK106YW (CheY**) failed to respond to CheZ, even when CheZ was expressed at high levels. Therefore, CheZ neither affects the flagellar motors directly nor sequesters CheY**. In in vitro cross-linking studies, CheY** promoted trimerization of CheZ to the same extent as wild-type CheY but failed to induce the formation of complexes of higher molecular weight observed with CheY-P. Also, CheY** could be cross-linked to FliM, the motor receptor protein, nearly as well as CheY-P. Thus, to CheZ, CheY** looks like CheY, but to FliM, it looks like CheY-P.
研究发现，大肠杆菌中缺失 $cheZ$ 基因的细胞和野生型细胞的行为对 $CheZ$ （一种已知能加速响应调节蛋白磷酸化 $CheY$ （$CheY-P$）去磷酸化的蛋白）的表达水平都非常敏感。 然而，被未磷酸化的突变蛋白 $CheY13DK106YW$ （$CheY^{}$）诱导进行游动和翻滚的细胞即使在 $CheZ$ 高水平表达时也无法对其作出反应。 因此，$CheZ$ 既不直接影响鞭毛马达，也不隔离 $CheY^{}$。 在体外交联研究中，$CheY^{}$ 促进 $CheZ$ 三聚化的程度与野生型 $CheY$ 相同，但未能诱导观察到的与 $CheY-P$ 形成的更高分子量复合物的形成。 此外，$CheY^{}$ 与鞭毛马达受体蛋白 $FliM$ 的交联程度几乎与 $CheY-P$ 相同。 因此，对于 $CheZ$ 来说，$CheY^{**}$ 看起来像 $CheY$，但对于 $FliM$ 来说，它看起来像 $CheY-P$。
