Zinc Uptake Regulator (zur) Gene Involved in Zinc Homeostasis and Virulence of Xanthomonas oryzae pv. oryzae in Rice

ABSTRACT Zinc is an essential trace element for all living organisms and plays pivotal roles in various cellular processes. However, an excess of zinc is extremely deleterious to cells. Bacteria have evolved complex machineries (such as efflux/influx systems) to control the concentration at levels appropriate for the maintenance of zinc homeostasis in cells and adaptation to the environment. The Zur (zinc uptake regulator) protein is one of these functional members involved in the precise control of zinc homeostasis. Here we identified a zur homologue designated 310 from Streptococcus suis serotype 2, strain 05ZYH33, a highly invasive isolate causing streptococcal toxic shock syndrome. Biochemical analysis revealed that the protein product of gene 310 exists as a dimer form and carries zinc ions. An isogenic gene replacement mutant of gene 310, the Δ310 mutant, was obtained by homologous recombination. Physiological tests demonstrated that the Δ310 mutant is specifically sensitive to Zn2+, while functional complementation of the Δ310 mutant can restore its duration capability, suggesting that 310 is a functional member of the Zur family. Two-dimensional electrophoresis indicated that nine proteins in the Δ310 mutant are overexpressed in comparison with those in the wild type. DNA microarray analyses suggested that 121 genes in the Δ310 mutant are affected, of which 72 genes are upregulated and 49 are downregulated. The transcriptome of S. suis serotype 2 with high Zn2+ concentrations also showed 117 differentially expressed genes, with 71 upregulated and 46 downregulated. Surprisingly, more than 70% of the genes differentially expressed in the Δ310 mutant were the same as those in S. suis serotype 2 that were differentially expressed in response to high Zn2+ concentration, consistent with the notion that 310 is involved in zinc homeostasis. We thus report for the first time a novel zinc-responsive regulator, Zur, from Streptococcus suis serotype 2.

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Identification, Functional Characterization, and Regulon Prediction of the Zinc Uptake Regulator (zur) of Bacillus anthracis – An Insight Into the Zinc Homeostasis of the Pathogen

Frontiers in Microbiology ◽

10.3389/fmicb.2018.03314 ◽

2019 ◽

Vol 9 ◽

Cited By ~ 7

Author(s):

Divya Kandari ◽

Monisha Gopalani ◽

Manish Gupta ◽

Hemant Joshi ◽

Sonika Bhatnagar ◽

...

Keyword(s):

Bacillus Anthracis ◽

Functional Characterization ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Zinc Uptake Regulator ◽

Insight Into

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Control of zinc homeostasis in Agrobacterium tumefaciens via zur and the zinc uptake genes znuABC and zinT

Microbiology ◽

10.1099/mic.0.082446-0 ◽

2014 ◽

Vol 160 (11) ◽

pp. 2452-2463 ◽

Cited By ~ 16

Author(s):

Sakkarin Bhubhanil ◽

Panida Sittipo ◽

Paweena Chaoprasid ◽

Sumontha Nookabkaew ◽

Rojana Sukchawalit ◽

...

Keyword(s):

Agrobacterium Tumefaciens ◽

Dominant Role ◽

Zinc Content ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Dependent Manner ◽

Transporter Family ◽

Zinc Depletion ◽

Zinc Uptake Regulator ◽

Dose Dependent

The Agrobacterium tumefaciens zinc uptake regulator (Zur) was shown to negatively regulate the zinc uptake genes znuABC, encoding a zinc transport system belonging to the ATP-binding cassette (ABC) transporter family, and zinT, which encodes a periplasmic zinc-binding protein. The expression of znuABC and zinT was inducible when cells were grown in medium containing a metal chelator (EDTA), and this induction was shown to be specific for zinc depletion. The expression of znuABC was reduced in response to increased zinc in a dose-dependent manner, and zinT had a less pronounced but similar pattern of zinc-regulated expression. The inactivation of zur led to constitutively high expression of znuABC and zinT. In addition, a zur mutant had an increased total zinc content compared to the WT NTL4 strain, whereas the inactivation of zinT caused a reduction in the total zinc content. The zinT gene is shown to play a dominant role and to be more important than znuA and znuB for A. tumefaciens survival under zinc deprivation. ZinT can function even when ZnuABC is inactivated. However, mutations in zur, znuA, znuB or zinT did not affect the virulence of A. tumefaciens.

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Bacterial zinc uptake regulator proteins and their regulons

Biochemical Society Transactions ◽

10.1042/bst20170228 ◽

2018 ◽

Vol 46 (4) ◽

pp. 983-1001 ◽

Cited By ~ 23

Author(s):

Alevtina Mikhaylina ◽

Amira Z. Ksibe ◽

David J. Scanlan ◽

Claudia A. Blindauer

Keyword(s):

Intracellular Trafficking ◽

Ribosomal Proteins ◽

Pathogenic Bacteria ◽

Transcriptional Regulators ◽

Research Area ◽

Essential Elements ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Dna Binding Affinity ◽

Zinc Uptake Regulator

All organisms must regulate the cellular uptake, efflux, and intracellular trafficking of essential elements, including d-block metal ions. In bacteria, such regulation is achieved by the action of metal-responsive transcriptional regulators. Among several families of zinc-responsive transcription factors, the ‘zinc uptake regulator’ Zur is the most widespread. Zur normally represses transcription in its zinc-bound form, in which DNA-binding affinity is enhanced allosterically. Experimental and bioinformatic searches for Zur-regulated genes have revealed that in many cases, Zur proteins govern zinc homeostasis in a much more profound way than merely through the expression of uptake systems. Zur regulons also comprise biosynthetic clusters for metallophore synthesis, ribosomal proteins, enzymes, and virulence factors. In recognition of the importance of zinc homeostasis at the host–pathogen interface, studying Zur regulons of pathogenic bacteria is a particularly active current research area.

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Coordinated Zinc Homeostasis Is Essential for the Wild-Type Virulence of Brucella abortus

Journal of Bacteriology ◽

10.1128/jb.02543-14 ◽

2015 ◽

Vol 197 (9) ◽

pp. 1582-1591 ◽

Cited By ~ 15

Author(s):

Lauren M. Sheehan ◽

James A. Budnick ◽

R. Martin Roop ◽

Clayton C. Caswell

Keyword(s):

Mouse Model ◽

Brucella Abortus ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Zinc Toxicity ◽

Uptake System ◽

Bacterial Cells ◽

Gene Encoding ◽

Content Type ◽

Genes Encoding

ABSTRACTMetal homeostasis in bacterial cells is a highly regulated process requiring intricately coordinated import and export, as well as precise sensing of intracellular metal concentrations. The uptake of zinc (Zn) has been linked to the virulence ofBrucella abortus; however, the capacity ofBrucellastrains to sense Zn levels and subsequently coordinate Zn homeostasis has not been described. Here, we show that expression of the genes encoding the zinc uptake system ZnuABC is negatively regulated by the Zn-sensing Fur family transcriptional regulator, Zur, by direct interactions between Zur and the promoter region ofznuABC. Moreover, the MerR-type regulator, ZntR, controls the expression of the gene encoding the Zn exporter ZntA by binding directly to its promoter. Deletion ofzurorzntRalone did not result in increased zinc toxicity in the corresponding mutants; however, deletion ofzntAled to increased sensitivity to Zn but not to other metals, such as Cu and Ni, suggesting that ZntA is a Zn-specific exporter. Strikingly, deletion ofzntRresulted in significant attenuation ofB. abortusin a mouse model of chronic infection, and subsequent experiments revealed that overexpression ofzntAin thezntRmutant is the molecular basis for its decreased virulence.IMPORTANCEThe importance of zinc uptake forBrucellapathogenesis has been demonstrated previously, but to date, there has been no description of how overall zinc homeostasis is maintained and genetically controlled in the brucellae. The present work defines the predominant zinc export system, as well as the key genetic regulators of both zinc uptake and export inBrucella abortus. Moreover, the data show the importance of precise coordination of the zinc homeostasis systems as disregulation of some elements of these systems leads to the attenuation ofBrucellavirulence in a mouse model. Overall, this study advances our understanding of the essential role of zinc in the pathogenesis of intracellular bacteria.

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A link between zinc uptake, bile salts, and a capsule required for virulence of a mastitis-associated extraintestinal pathogenic Escherichia coli strain

10.1101/2020.06.25.172775 ◽

2020 ◽

Author(s):

Michael A. Olson ◽

Aleksander Grimsrud ◽

Amanda C. Richards ◽

Matthew A. Mulvey ◽

Eric Wilson ◽

...

Keyword(s):

Escherichia Coli ◽

Bile Salts ◽

Bloodstream Infections ◽

Mouse Mammary Gland ◽

Coli Strain ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Growth Delay ◽

Capsule Production

ABSTRACTExtraintestinal pathogenic Escherichia coli (ExPEC) are major causes of urinary and bloodstream infections. ExPEC reservoirs are not completely understood. Some mastitis-associated E. coli (MAEC) strains carry genes associated with ExPEC virulence, including metal scavenging, immune avoidance, and host attachment functions. In this study, we investigated the role of the high-affinity zinc uptake (znuABC) system in the MAEC strain M12. Elimination of znuABC moderately decreased fitness during mouse mammary gland infections. The ΔznuABC mutant strain exhibited an unexpected growth delay in the presence of bile salts, which was alleviated by the addition of excess zinc. We isolated ΔznuABC mutant suppressor mutants with improved growth of in bile salts, several of which no longer produced the K96 capsule made by strain M12. Addition of bile salts also reduced capsule production by strain M12 and ExPEC strain CP9, suggesting that capsule synthesis may be detrimental when bile salts are present. To better understand the role of the capsule, we compared the virulence of mastitis strain M12 with its unencapsulated ΔkpsCS mutant in two models of ExPEC disease. The wild type strain successfully colonized mouse bladders and kidneys and was highly virulent in intraperitoneal infections. Conversely, the ΔkpsCS mutant was unable to colonize kidneys and was unable to cause sepsis. These results demonstrate that some MAEC may be capable of causing human ExPEC illness. Virulence of strain M12 in these infections is dependent on its capsule. However, capsule may interfere with zinc homeostasis in the presence of bile salts while in the digestive tract.

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The histidine-rich loop in the extracellular domain of ZIP4 binds zinc and plays a role in zinc transport

Biochemical Journal ◽

10.1042/bcj20190108 ◽

2019 ◽

Vol 476 (12) ◽

pp. 1791-1803 ◽

Cited By ~ 4

Author(s):

Tuo Zhang ◽

Eziz Kuliyev ◽

Dexin Sui ◽

Jian Hu

Keyword(s):

Extracellular Domain ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Zinc Binding ◽

Functional Study ◽

Acrodermatitis Enteropathica ◽

Zinc Transport ◽

Metal Transporters ◽

Histidine Residues ◽

Zip Family

Abstract The Zrt-/Irt-like protein (ZIP) family mediates zinc influx from extracellular space or intracellular vesicles/organelles, playing a central role in systemic and cellular zinc homeostasis. Out of the 14 family members encoded in human genome, ZIP4 is exclusively responsible for zinc uptake from dietary food and dysfunctional mutations of ZIP4 cause a life-threatening genetic disorder, Acrodermatitis Enteropathica (AE). About half of the missense AE-causing mutations occur within the large N-terminal extracellular domain (ECD), and our previous study has shown that ZIP4–ECD is crucial for optimal zinc uptake but the underlying mechanism has not been clarified. In this work, we examined zinc binding to the isolated ZIP4–ECD from Pteropus Alecto (black fruit bat) and located zinc-binding sites with a low micromolar affinity within a histidine-rich loop ubiquitously present in ZIP4 proteins. Zinc binding to this protease-susceptible loop induces a small and highly localized structural perturbation. Mutagenesis and functional study on human ZIP4 by using an improved cell-based zinc uptake assay indicated that the histidine residues within this loop are not involved in preselection of metal substrate but play a role in promoting zinc transport. The possible function of the histidine-rich loop as a metal chaperone facilitating zinc binding to the transport site and/or a zinc sensor allosterically regulating the transport machinery was discussed. This work helps to establish the structure/function relationship of ZIP4 and also sheds light on other metal transporters and metalloproteins with clustered histidine residues.

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Defining the Role of theStreptococcus agalactiaeSht-Family Proteins in Zinc Acquisition and Complement Evasion

Journal of Bacteriology ◽

10.1128/jb.00757-18 ◽

2019 ◽

Vol 201 (8) ◽

Cited By ~ 5

Author(s):

P. Moulin ◽

V. Rong ◽

A. Ribeiro E Silva ◽

V. G. Pederick ◽

E. Camiade ◽

...

Keyword(s):

Human Blood ◽

Streptococcus Agalactiae ◽

Metal Ion ◽

Binding Proteins ◽

Factor H ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Content Type

ABSTRACTStreptococcus agalactiaeis not only part of the human intestinal and urogenital microbiota but is also a leading cause of septicemia and meningitis in neonates. Its ability to cause disease depends upon the acquisition of nutrients from its environment, including the transition metal ion zinc. The primary zinc acquisition system of the pathogen is the Adc/Lmb ABC permease, which is essential for viability in zinc-restricted environments. Here, we show that in addition to the AdcCB transporter and the three zinc-binding proteins, Lmb, AdcA, and AdcAII,S. agalactiaezinc homeostasis also involves two streptococcal histidine triad (Sht) proteins. Sht and ShtII are required for zinc uptake via the Lmb and AdcAII proteins with apparent overlapping functionality and specificity. Both Sht-family proteins possess five-histidine triad motifs with similar hierarchies of importance for Zn homeostasis. Independent of its contribution to zinc homeostasis, Sht has previously been reported to bind factor H leading to predictions of a contribution to complement evasion. Here, we investigated ShtII to ascertain whether it had similar properties. Analysis of recombinant Sht and ShtII reveals that both proteins have similar affinities for factor H binding. However, neither protein aided in resistance to complement in human blood. These findings challenge prior inferences regarding thein vivorole of the Sht proteins in resisting complement‐mediated clearance.IMPORTANCEThis study examined the role of the two streptococcal histidine triad (Sht) proteins ofStreptococcus agalactiaein zinc homeostasis and complement resistance. We showed that Sht and ShtII facilitate zinc homeostasis in conjunction with the metal-binding proteins Lmb and AdcAII. Here, we show that the Sht-family proteins are functionally redundant with overlapping roles in zinc uptake. Further, this work reveals that although the Sht-family proteins bind to factor Hin vitrothis did not influence survival in human blood.

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A Guide to Human Zinc Absorption: General Overview and Recent Advances of In Vitro Intestinal Models

Nutrients ◽

10.3390/nu12030762 ◽

2020 ◽

Vol 12 (3) ◽

pp. 762 ◽

Cited By ~ 15

Author(s):

Maria Maares ◽

Hajo Haase

Keyword(s):

Intestinal Epithelium ◽

Current Knowledge ◽

In Vitro Digestion ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Intestinal Cell ◽

Zinc Absorption ◽

Intestinal Cell Line

Zinc absorption in the small intestine is one of the main mechanisms regulating the systemic homeostasis of this essential trace element. This review summarizes the key aspects of human zinc homeostasis and distribution. In particular, current knowledge on human intestinal zinc absorption and the influence of diet-derived factors on bioaccessibility and bioavailability as well as intrinsic luminal and basolateral factors with an impact on zinc uptake are discussed. Their investigation is increasingly performed using in vitro cellular intestinal models, which are continually being refined and keep gaining importance for studying zinc uptake and transport via the human intestinal epithelium. The vast majority of these models is based on the human intestinal cell line Caco-2 in combination with other relevant components of the intestinal epithelium, such as mucin-secreting goblet cells and in vitro digestion models, and applying improved compositions of apical and basolateral media to mimic the in vivo situation as closely as possible. Particular emphasis is placed on summarizing previous applications as well as key results of these models, comparing their results to data obtained in humans, and discussing their advantages and limitations.

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