Protein–protein association and cellular localization of four essential gene products encoded by tellurite resistance-conferring cluster “ter” from pathogenic Escherichia coli

Abstract

Gene cluster "ter" conferring high tellurite resistance has been identified in various pathogenic bacteria including Escherichia coli O157:H7. However, the precise mechanism as well as the molecular function of the respective gene products is unclear. Here we describe protein-protein association and localization analyses of four essential Ter proteins encoded by minimal resistance-conferring fragment (terBCDE) by means of recombinant expression. By using a two-plasmid complementation system we show that the overproduced single Ter proteins are not able to mediate tellurite resistance, but all Ter members play an irreplaceable role within the cluster. We identified several types of homotypic and heterotypic protein-protein associations among the Ter proteins by in vitro and in vivo pull-down assays and determined their cellular localization by cytosol/membrane fractionation. Our results strongly suggest that Ter proteins function involves their mutual association, which probably happens at the interface of the inner plasma membrane and the cytosol.

Role of Tellurite Resistance Operon in Filamentous Growth of Yersinia pestis in Macrophages

“…Protein TerD and TerE form strong heterodimeric complexes. Further, protein localization analyzes indicate that TerC may serve as a membrane protein and on its cytoplasmic side interacts with TerB and TerE, and the latter of these proteins further associates with TerD present in the cytoplasm [ 41 ]. These findings support the speculation that the Ter proteins are involved in as yet uncharacterized bacterial stress recognizing mechanism operating during infection processes.…”

Extreme Environments and High-Level Bacterial Tellurite Resistance

“…The elements can be chromosomally encoded as well, such as tehAB from E. coli [96], trgABcysK and telA from R. sphaeroides [134], and the tmp gene from Pseudomonas syringae [135]. However, the molecular basis behind most of these systems is unclear [136]. Other strategies are employed for resistance; however, they do not involve direct enzymatic reduction.…”

“…It does confer high-level resistance (minimum inhibitory concentration (MIC) of 1028 µ g/mL), but the details are still under study. Work with the minimal resistance-conferring fragment (terBCDE) has shown that resistance can only be achieved by the expression of all four components [136]. In this case, they each play an irreplaceable role, likely involving their mutual association at the inner membrane [136].…”

“…Work with the minimal resistance-conferring fragment (terBCDE) has shown that resistance can only be achieved by the expression of all four components [136]. In this case, they each play an irreplaceable role, likely involving their mutual association at the inner membrane [136]. Also, some of the individual genes from the operon actually appear to be lethal when cloned alone, making them difficult to study [153].…”

“…TerZABCDEF provides resistance to phages and pore-forming colicins, and it is also found in pathogenic bacteria, which have no need for tellurite resistance. Therefore, it is believed to serve some unknown function which increases fitness [136]. Also, TerD and TerE are involved in intracellular survival and the proliferation of Yersinia pestis in macrophages [154].…”