Role of the High-Affinity Zinc Uptake znuABC System in Salmonella enterica Serovar Typhimurium Virulence

Abstract

The Salmonella enterica serovar Typhimurium znuABC genes encoding a high-affinity zinc uptake system and its regulatory zur gene have been cloned. Salmonella serovar Typhimurium zur and znuC knockout mutants have been constructed by marker exchange. The 50% lethal dose of the znuC mutant increased when either orally or intraperitoneally inoculated in BALB/c mice, while virulence of the zur mutant decreased only when mice were intraperitoneally challenged.

A Novel Zinc Binding System, ZevAB, Is Critical for Survival of Nontypeable Haemophilus influenzae in a Murine Lung Infection Model

“…3B. A znuBC deletion, which was also constructed by gene replacement, exhibited defects similar to those of the znuA mutant during growth in rich medium or medium containing 0.5 mM EDTA (data not shown), providing evidence that ZnuBC functions together with ZnuA in NTHI as components of the zinc transport system described previously for other organisms (11,21,53).…”

“…Comparison of our list of potential DsbA substrates to the results of HITS revealed three genes that fit these criteria: znuA (s.i., 0.101), encoding the periplasmic component of a high-affinity zinc uptake transporter (39, 53), nlpD (s.i., 0.000), encoding a lipoprotein suggested to be involved in daughter cell separation (64,65), and HI1249 (s.i., 0.106), encoding a putative protein herein referred to as ZevA. The role of znuA in virulence has been studied by several groups (3,11,14,21,36,57,75), and nlpD has been implicated in the virulence of Yersinia pestis and Yersinia enterocolitica (12,64). However, zevA has not been previously investigated and its role in virulence is unknown.…”

“…An H. influenzae znuA (originally called pzp1) mutant was shown to exhibit growth defects in normal medium that could be rescued by addition of zinc, and recombinant ZnuA bound up to 5 molecules of zinc per protein (39). The znuBC genes have also been demonstrated to participate in zinc utilization in other organisms (11,53), including Pasteurella multocida (21), a close relative of H. influenzae, and are thought to encode the ATPase (znuC) and membrane permease (znuB) components of the transporter (52,53). To evaluate the conditions under which ZevAB and ZnuABC are needed, their relative contributions to the growth of H. influenzae were examined through single and double mutant analyses.…”

“…Here, we generated a list of potential substrates of the periplasmic disulfide oxidoreductase protein DsbA (see Table S2 in the supplemental material) and integrated our findings with the results of a previous study in which HITS technology was used to identify genes required for lung infection (22). Using this strategy, we identified three genes that were potentially important for lung infection, including two, znuA and nlpD, that had previously been implicated in the virulence of several organisms (3,11,12,14,21,36,57,64,75), and a third gene, zevA, whose function had not been determined. Therefore, zevA and its neighboring gene, zevB, were investigated for their roles in the pathogenesis of a clinical NTHI isolate.…”

“…Metal-restricted growth conditions can be generated by titration of the medium with increasing concentrations of EDTA (3,11,54). To determine whether zevAB is involved in metal acquisition in H. influenzae, strains were grown in medium containing 0.25, 0.5, or 0.75 mM EDTA.…”