Gibson K E, Silhavy T J
Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
J Bacteriol. 1999 Jan;181(2):563-71. doi: 10.1128/JB.181.2.563-571.1999.
Synthesis of the OmpF porin of Escherichia coli is regulated in response to environmental and growth phase signals. In order to identify constituents of the various regulatory pathways involved in modulating ompF transcriptional expression, transposon insertion mutagenesis was performed and mutations that increased ompF'-lacZ activity were identified as previously described. Mutations mapping to a previously identified gene of unknown function, lrhA, were obtained. We found that LrhA, a LysR homolog, functions as a regulatory component in the RpoS-dependent growth phase repression of ompF. In addition to altered growth phase regulation of ompF, these lrhA mutants have pleiotropic stationary-phase defects as a result of decreased RpoS levels. We provide evidence that LrhA promotes degradation of RpoS by functioning within a genetic pathway that includes the response regulator SprE and the ClpXP protease. LrhA functions upstream of the other components in the pathway and appears to modulate the activity of SprE.
大肠杆菌外膜孔蛋白OmpF的合成受环境和生长阶段信号的调节。为了鉴定参与调节ompF转录表达的各种调控途径的组成成分，我们进行了转座子插入诱变，并按照之前描述的方法鉴定出增加ompF'-lacZ活性的突变。获得了定位到一个先前鉴定的功能未知基因lrhA上的突变。我们发现，LrhA作为一种赖氨酸阻遏物同源物，在RpoS依赖的生长阶段对ompF的抑制中起调控作用。除了ompF生长阶段调控的改变外，这些lrhA突变体由于RpoS水平降低而具有多效性的稳定期缺陷。我们提供的证据表明，LrhA通过在一个包括应答调节因子SprE和ClpXP蛋白酶的遗传途径中发挥作用来促进RpoS的降解。LrhA在该途径中其他成分的上游发挥作用，并且似乎调节SprE的活性。
