Zinc transporters YbtX and ZnuABC are required for the virulence of Yersinia pestis in bubonic and pneumonic plague in mice

Abstract

A number of bacterial pathogens require the ZnuABC Zinc (Zn2+) transporter and/or a second Zn2+ transport system to overcome Zn2+ sequestration by mammalian hosts. Previously we have shown that in addition to ZnuABC, Yersinia pestis possesses a second Zn2+ transporter that involves components of the yersiniabactin (Ybt), siderophore-dependent iron transport system. Synthesis of the Ybt siderophore and YbtX, a member of the major facilitator superfamily, are both critical components of the second Zn2+ transport system. Here we demonstrate that a ybtX znu double mutant is essentially avirulent in mouse models of bubonic and pneumonic plague while a ybtX mutant retains high virulence in both plague models. While sequestration of host Zn is a key nutritional immunity factor, excess Zn appears to have a significant antimicrobial role in controlling intracellular bacterial survival. Here, we demonstrate that ZntA, a Zn2+ exporter, plays a role in resistance to Zn toxicity in vitro, but that a zntA zur double mutant retains high virulence in both pneumonic and bubonic plague models and survival in macrophages. We also confirm that Ybt does not directly bind Zn2+ in vitro under the conditions tested. However, we detect a significant increase in Zn2+-binding ability of filtered supernatants from a Ybt+ strain compared to those from a strain unable to produce the siderophore, supporting our previously published data that Ybt biosynthetic genes are involved in the production of a secreted Zn-binding molecule (zincophore). Our data suggest that Ybt or a modified Ybt participate in or promote Zn-binding activity in culture supernatants and is involved in Zn acquisition in Y. pestis.

Uropathogenic enterobacteria use the yersiniabactin metallophore system to acquire nickel

“…While TonB/ExbB/ExbD-dependent transport systems such as FyuA are classically associated with iron import, they have also been implicated in nickel uptake by H. pylori (51). This Ni-Ybt import pathway is distinct from the putative zinc import activity associated with the Yersinia HPI in Y. pestis that is thought to proceed via YbtX (52,53). Where metal-Ybt import and trafficking pathways diverge to direct each ion to its distinctive metalloenzymes or storage proteins remains unclear.…”

The Cyclic AMP Receptor Protein Regulates Quorum Sensing and Global Gene Expression in Yersinia pestis During Planktonic Growth and Growth in Biofilms

“…A unique result of our transcriptional profiling was the observed indirect repression of Ybt genes by Crp ( Table 1 and Table S2). The Ybt and irp genes are critical for iron acquisition, virulence, and inflammation during pneumonic plague (48)(49)(50). Expression of these genes may be higher up to 48 hpi, when expression and activity of Crp is low (Fig.…”

“…Consequently, expression of the irp genes, required for Ybt production, and genes for heme transport were also decreased, but genes for the Yfe and Feo transport systems were not significantly differentially expressed (Table 1). Crp also represses expression of ybtX (irp8 in strain CO92), a known virulence factor and trigger of inflammation during pneumonic plague (48,49).…”

Yersiniabactin metal binding characterization and removal of nickel from industrial wastewater

“…Ybt is currently reported to bind Al 3+ , Cr 2+ , Co 2+ , Cu 2+ , Ga 3+ , Fe 3+ , and Ni 2+ . It is also hypothesized to bind zinc, though no confirmatory mass spectrometry data have been presented . In previous work from our group, Ybt has been applied to bind metal compounds from solid surfaces and liquid samples in the context of iron and copper removal, respectively .…”

“…8,9 It is also hypothesized to bind zinc, though no confirmatory mass spectrometry data have been presented. 9,14,15 In previous work from our group, Ybt has been applied to bind metal compounds from solid surfaces and liquid samples in the context of iron and copper removal, respectively. 16,17 For the latter effort of aqueous stream metal removal, the Ybt compound was noncovalently adsorbed to polymeric resin (XAD-16N, henceforth referred to as Ybt-XAD) to facilitate the heterogeneous interaction with liquid samples.…”