Characterization of <italic>che W</italic> Genes of <italic>Leptospira interrogans</italic> and their Effects in <italic>Escherichia coli</italic>

Abstract

The motility and chemotaxis systems are critical for the virulence of leptospires. In this study, the phylogenetic profiles method was used to predict the interaction of chemotaxis proteins. It was shown that CheW1 links to CheA1, CheY, CheB and CheW2; CheW3 links to CheA2, MCP (LA2426), CheB3 and CheD1; and CheW2 links only to CheW1. The similarity analysis demonstrated that CheW2 of Leptospira interrogans strain Lai had poor homology with CheW of Escherichia coli in the region of residues 30-50. In order to verify the function of these proteins, the putative cheW genes were cloned into pQE31 vector and expressed in wild-type E. coli strain RP437 or cheW defective strain RP4606. The swarming results indicated that CheW1 and CheW3 could restore swarming of RP4606 while CheW2 could not. Overexpression of CheW1 and CheW3 in RP437 inhibited the swarming of RP437, whereas the inhibitory effect of CheW2 was much lower. Therefore, we presumed that CheW1 and CheW3 might have the function of CheW while CheW2 does not. The existence of multiple copies of chemotaxis homologue genes suggested that L. interrogans strain Lai might have a more complex chemosensory pathway.

Isothermal oxidation behavior of a thermal barrier coating prepared using EB-PVD

“…It has been reported that an as‐deposited interfacial oxide is formed after the deposition process, as a result of the reduction reaction between the elements of the BC and zirconia. During the initial oxidation, the oxygen partial pressure of the BC with a fresher surface was much greater than the dissociation pressure of the corresponding oxides, and this promoted the non‐selective oxidation.…”

Genetic and molecular biological characterization of two homologous <italic>cheR</italic> genes from <italic>Leptospira interrogans</italic>

“…Based on this expression profile and our previous functional analyses [23][24][25], the phosphor group and methyl group transfer processes in L. interrogans could be roughly modeled similar to that of E. coli. When attractants bind to MCPs, the kinase activity of CheA1 rapidly drops, and then recovers back to its steady-state level by the methylation of MCPs catalyzed by CheR2.…”

“…On the other hand, some putative homologous genes with high value of amino acid sequence similarity may be either cryptic or pseudogenes. For instance, although the methylesterase CheB1 and CheB3 of L. interrogans were shown to have similar functions to their counterparts in E. coli, the special domain architecture of CheB2 might destroy its function involved in the swarming process of E. coli [23].…”

“…A series of chemosensory system-related proteins, CheW1, CheW3, CheY1-5, CheB1, and CheB3, from L. interrogans have been shown to exert similar functions, like their homologous proteins of E. coli [23][24][25]. On the other hand, neither CheW2 nor CheB2 could perform any chemotaxis signal transduction functions in E. coli.…”

“…Plasmid pREP4 has lacI q for negatively regulating the expression from the T5 promoter, thereby reducing 'leaky' expression. In order to confirm the correct expression of fused proteins in RP437 and RP1254, western blot analysis was carried out as described previously [23][24][25].…”