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

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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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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Delineation of the Residues of Bacillus anthracis Zinc Uptake Regulator Protein Directly Involved in Its Interaction with Cognate DNA

Biological Trace Element Research ◽

10.1007/s12011-020-02427-x ◽

2020 ◽

Author(s):

Divya Kandari ◽

Hemant Joshi ◽

Neetu Tanwar ◽

Manoj Munde ◽

Rakesh Bhatnagar

Keyword(s):

Bacillus Anthracis ◽

Zinc Uptake ◽

Regulator Protein ◽

Zinc Uptake Regulator

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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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Putative ligand binding sites of two functionally characterized bark beetle odorant receptors

BMC Biology ◽

10.1186/s12915-020-00946-6 ◽

2021 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Jothi K. Yuvaraj ◽

Rebecca E. Roberts ◽

Yonathan Sonntag ◽

Xiao-Qing Hou ◽

Ewald Grosse-Wilde ◽

...

Keyword(s):

Ligand Binding ◽

Bark Beetle ◽

Pest Control ◽

Binding Sites ◽

Functional Characterization ◽

Site Directed Mutagenesis ◽

Odorant Receptors ◽

Functional Evolution ◽

General Importance ◽

Insight Into

Abstract Background Bark beetles are major pests of conifer forests, and their behavior is primarily mediated via olfaction. Targeting the odorant receptors (ORs) may thus provide avenues towards improved pest control. Such an approach requires information on the function of ORs and their interactions with ligands, which is also essential for understanding the functional evolution of these receptors. Hence, we aimed to identify a high-quality complement of ORs from the destructive spruce bark beetle Ips typographus (Coleoptera, Curculionidae, Scolytinae) and analyze their antennal expression and phylogenetic relationships with ORs from other beetles. Using 68 biologically relevant test compounds, we next aimed to functionally characterize ecologically important ORs, using two systems for heterologous expression. Our final aim was to gain insight into the ligand-OR interaction of the functionally characterized ORs, using a combination of computational and experimental methods. Results We annotated 73 ORs from an antennal transcriptome of I. typographus and report the functional characterization of two ORs (ItypOR46 and ItypOR49), which are responsive to single enantiomers of the common bark beetle pheromone compounds ipsenol and ipsdienol, respectively. Their responses and antennal expression correlate with the specificities, localizations, and/or abundances of olfactory sensory neurons detecting these enantiomers. We use homology modeling and molecular docking to predict their binding sites. Our models reveal a likely binding cleft lined with residues that previously have been shown to affect the responses of insect ORs. Within this cleft, the active ligands are predicted to specifically interact with residues Tyr84 and Thr205 in ItypOR46. The suggested importance of these residues in the activation by ipsenol is experimentally supported through site-directed mutagenesis and functional testing, and hydrogen bonding appears key in pheromone binding. Conclusions The emerging insight into ligand binding in the two characterized ItypORs has a general importance for our understanding of the molecular and functional evolution of the insect OR gene family. Due to the ecological importance of the characterized receptors and widespread use of ipsenol and ipsdienol in bark beetle chemical communication, these ORs should be evaluated for their potential use in pest control and biosensors to detect bark beetle infestations.

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Identification of Thyroid Hormones and Functional Characterization of Thyroid Hormone Receptor in the Pacific Oyster Crassostrea gigas Provide Insight into Evolution of the Thyroid Hormone System

PLoS ONE ◽

10.1371/journal.pone.0144991 ◽

2015 ◽

Vol 10 (12) ◽

pp. e0144991 ◽

Cited By ~ 22

Author(s):

Wen Huang ◽

Fei Xu ◽

Tao Qu ◽

Rui Zhang ◽

Li Li ◽

...

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormones ◽

Hormone Receptor ◽

Pacific Oyster ◽

Thyroid Hormone Receptor ◽

Functional Characterization ◽

The Pacific ◽

Hormone System ◽

Insight Into

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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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Molecular cloning and functional characterization of novel zinc transporter rZip10 (Slc39a10) involved in zinc uptake across rat renal brush-border membrane

AJP Renal Physiology ◽

10.1152/ajprenal.00014.2006 ◽

2007 ◽

Vol 292 (1) ◽

pp. F217-F229 ◽

Cited By ~ 34

Author(s):

P. Kaler ◽

R. Prasad

Keyword(s):

Functional Characterization ◽

Zinc Transporter ◽

Zinc Uptake ◽

Local Alignment ◽

Cooh Group ◽

Transporter Protein ◽

Renal Brush Border Membrane ◽

Insertional Inactivation ◽

Zinc Concentrations ◽

Uptake Activity

Previously, in our laboratory a 40-kDa zinc transporter protein was purified and functionally reconstituted in proteoliposomes (Kumar R, Prasad R. Biochim Biophys Acta 1419: 23–32, 1999). Furthermore, we now report the identification of Slc39a10 cDNA encoding the 40-kDa zinc transporter protein by isolating a cloned DNA complementary to zinc transporter mRNA. cDNA was constructed from immunoenriched mRNA encoding the zinc transporter. cDNA was inserted into pBR322 using poly(dC)- poly(dG) tailing. Escherichia coli DH5α cells were transformed, and colonies were screened for zinc transporter cDNA by insertional inactivation. Plasmid DNA was purified from the ampicillin-sensitive clones, and the cDNA was sequenced from both strands. A basic local alignment research tool (BLAST) search of cDNA revealed that it belongs to the Slc39 gene family of zinc transporters and was designated as Slc39a10. Zinc transporter protein deduced on the basis of cDNA sequence was named rZip10 and consists of 385 amino acids with 9 predicted transmembrane domains. The Slc39a10 gene was abundantly expressed in both rat and human tissues. Increased extracellular zinc concentration resulted in upregulation of Slc39a10 in LLC-PK1cells expressing rZip10, which was downregulated at higher zinc concentrations. These cells accumulated more zinc than control cells. rZip10-mediated zinc uptake activity was time-, temperature-, and concentration-dependent and saturable which followed Michaelis-Menten kinetics with a Kmof 19.2 μM and Vmaxof 50 pmol·min−1·mg protein−1. This activity was competitively inhibited by cadmium with Kiof 91 μM. rZip10-mediated zinc uptake was inhibited by COOH group-modifying agents such as DCC. Immunofluorescence studies showed that rZip10 localizes to the plasma membrane of LLC-PK1cells.

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Structural and functional characterization of mouse U7 small nuclear RNA active in 3' processing of histone pre-mRNA.

Molecular and Cellular Biology ◽

10.1128/mcb.8.4.1518 ◽

1988 ◽

Vol 8 (4) ◽

pp. 1518-1524 ◽

Cited By ~ 41

Author(s):

D Soldati ◽

D Schümperli

Keyword(s):

Sea Urchin ◽

Functional Characterization ◽

Rnase H ◽

Primer Extension ◽

Small Nuclear Rna ◽

Nuclear Rna ◽

Processing Signal ◽

Insight Into

Oligonucleotides derived from the spacer element of the histone RNA 3' processing signal were used to characterize mouse U7 small nuclear RNA (snRNA), i.e., the snRNA component active in 3' processing of histone pre-mRNA. Under RNase H conditions, such oligonucleotides inhibited the processing reaction, indicating the formation of a DNA-RNA hybrid with a functional ribonucleoprotein component. Moreover, these oligonucleotides hybridized to a single nuclear RNA species of approximately 65 nucleotides. The sequence of this RNA was determined by primer extension experiments and was found to bear several structural similarities with sea urchin U7 snRNA. The comparison of mouse and sea urchin U7 snRNA structures yields some further insight into the mechanism of histone RNA 3' processing.

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