Znu Is the Predominant Zinc Importer in Yersinia pestis during In Vitro Growth but Is Not Essential for Virulence

Abstract

Little is known about Zn homeostasis inZinc (Zn) is an essential trace metal required to preserve the biological function and/or structural integrity of numerous enzymes and proteins in all eukaryotic and prokaryotic cells (3,49,99). Procuring sufficient Zn to sustain growth during mammalian infection is a considerable challenge for bacterial pathogens (56). Serum levels of Zn are in the micromolar range, and the metal's bioavailability is restricted further because it is tightly bound to proteins and not freely exchangeable (35,85,88,103). In addition, as with iron (Fe), mammals sequester Zn systemically and locally in an attempt to deprive invading pathogens of this critical micronutrient (35,85,88,103). Bacteria, therefore, must depend upon the expression of high-affinity Zn uptake systems to compete successfully with the mammalian host for this metal. Although Zn is essential, high concentrations are toxic because of its proclivity to occupy ligand sites intended for other transition metals, such as Mn and Fe (39); consequently, bacteria must strictly control intracellular Zn levels to avoid disruption of physiological processes (49). Two major mechanisms by which Zn homeostasis is achieved are metal effluxers and regulation of Zn uptake systems.The discovery of the cluster 9 (C9) family of transition metal ATP-binding cassette (ABC) transporters significantly advanced our understanding of bacterial Zn metabolism (19). The function of the C9 family was revealed primarily through genetic studies in which the growth defects of mutants under metal-limiting conditions were reversed by supplementation with Zn (27,77) or Mn (8,27,59). Bioinformatic analyses of the C9 solute-binding protein (SBP) components, which capture metals within the periplasmic space and ferry them to the cytoplasmic membrane-bound permease complex, revealed a bimodal clustering pattern appearing to correlate with experimentally proven metal specificities (19). One subcluster con-* Corresponding author. Mailing address:

Manganese transporters Yfe and MntH are Fur-regulated and important for the virulence of Yersinia pestis

“…Bioinformatic analysis of potential Mn transporters in Y. pestis KIM We had previously implicated the Yfe ABC transporter in Fe and Mn uptake in Y. pestis (Bearden & Perry, 1999;Desrosiers et al, 2010). To identify any additional SBPs in Y. pestis KIM that might be involved in Mn transport, we searched the KIM10+ genome with the sequence of MntC, the periplasmic Mn-binding component of an ABC transporter from N. gonorrhoeae (Lim et al, 2008) Perry et al, 2007).…”

“…In Y. pestis, expression of feoABC under aerobic conditions in the presence of Fe, the ability of YfeA to bind Zn in the periplasm but not transport it into the cell, as well as dual Mn and Fe repression of mntH and yfe, may contribute to this homeostasis in different mammalian organ systems and perhaps in the flea (Bearden et al, 1998;Desrosiers et al, 2010;J. D. Fetherston and others, unpublished results;Perry et al, 2003Perry et al, , 2007.…”

“…Some members of the A-1 cluster show specificity for Mn or Zn; others seem to have multiple transition metal substrates (Berntsson et al, 2010;Claverys, 2001;Papp-Wallace & Maguire, 2006). The Yfe/Sit systems, which are members of this cluster, have been shown to acquire Mn and Fe in Y. pestis, Escherichia coli, Salmonella enterica serovar Typhimurium (S. Typhimurium) and Shigella flexneri (Bearden et al, 1998;Bearden & Perry, 1999;Desrosiers et al, 2010;Hazlett et al, 2003;Janakiraman & Slauch, 2000;Janulczyk et al, 1999Janulczyk et al, , 2003Kehres et al, 2002a;Paik et al, 2003;Runyen-Janecky et al, 2006Sabri et al, 2006).…”

“…A yfe mntH double mutant did exhibit a moderate growth defect which was alleviated by supplementation with Mn. No short-term energy-dependent uptake of 54 Bearden & Perry, 1999;Desrosiers et al, 2010;Hazlett et al, 2003;Janakiraman & Slauch, 2000;Janulczyk et al, 1999Janulczyk et al, , 2003Kehres et al, 2002a;Paik et al, 2003;Runyen-Janecky et al, 2006Sabri et al, 2006).…”

Two Zinc Uptake Systems Contribute to the Full Virulence of Listeria monocytogenes during Growth In Vitro and In Vivo

“…This is consistent with S. enterica serovar Typhimurium experiencing zinc deficiency within the modified phagosome of host cells. The observation that mutants of Yersinia pestis defective for zinc uptake were unaffected in a mouse model of virulence (9) would indicate that the availability of zinc to the pathogen will be determined by the niche occupied within the host.…”