scholarly journals Probing the Structure and Function of the Cytosolic Domain of the Human Zinc Transporter ZnT8 with Nickel(II) Ions

2021 ◽  
Vol 22 (6) ◽  
pp. 2940
Author(s):  
Maria Carmen Catapano ◽  
Douglas S. Parsons ◽  
Radosław Kotuniak ◽  
Přemysl Mladěnka ◽  
Wojciech Bal ◽  
...  
Keyword(s):  
Metal Binding ◽  
Structure And Function ◽  
Zinc Transporter ◽  
Human Protein ◽  
Zinc Binding ◽  
Zinc Ions ◽  
Zinc Transport ◽  
Bacterial Proteins ◽  
Cytosolic Domain ◽  
And Function

The human zinc transporter ZnT8 provides the granules of pancreatic β-cells with zinc (II) ions for assembly of insulin hexamers for storage. Until recently, the structure and function of human ZnTs have been modelled on the basis of the 3D structures of bacterial zinc exporters, which form homodimers with each monomer having six transmembrane α-helices harbouring the zinc transport site and a cytosolic domain with an α,β structure and additional zinc-binding sites. However, there are important differences in function as the bacterial proteins export an excess of zinc ions from the bacterial cytoplasm, whereas ZnT8 exports zinc ions into subcellular vesicles when there is no apparent excess of cytosolic zinc ions. Indeed, recent structural investigations of human ZnT8 show differences in metal binding in the cytosolic domain when compared to the bacterial proteins. Two common variants, one with tryptophan (W) and the other with arginine (R) at position 325, have generated considerable interest as the R-variant is associated with a higher risk of developing type 2 diabetes. Since the mutation is at the apex of the cytosolic domain facing towards the cytosol, it is not clear how it can affect zinc transport through the transmembrane domain. We expressed the cytosolic domain of both variants of human ZnT8 and have begun structural and functional studies. We found that (i) the metal binding of the human protein is different from that of the bacterial proteins, (ii) the human protein has a C-terminal extension with three cysteine residues that bind a zinc(II) ion, and (iii) there are small differences in stability between the two variants. In this investigation, we employed nickel(II) ions as a probe for the spectroscopically silent Zn(II) ions and utilised colorimetric and fluorimetric indicators for Ni(II) ions to investigate metal binding. We established Ni(II) coordination to the C-terminal cysteines and found differences in metal affinity and coordination in the two ZnT8 variants. These structural differences are thought to be critical for the functional differences regarding the diabetes risk. Further insight into the assembly of the metal centres in the cytosolic domain was gained from potentiometric investigations of zinc binding to synthetic peptides corresponding to N-terminal and C-terminal sequences of ZnT8 bearing the metal-coordinating ligands. Our work suggests the involvement of the C-terminal cysteines, which are part of the cytosolic domain, in a metal chelation and/or acquisition mechanism and, as now supported by the high-resolution structural work, provides the first example of metal-thiolate coordination chemistry in zinc transporters.

scholarly journals Transmembrane 163 (TMEM163) Protein: A New Member of the Zinc Efflux Transporter Family

2020 ◽  
Author(s):  
Daniel J. Styrpejko ◽  
Math P. Cuajungco
Keyword(s):  
Protein A ◽  
Structure And Function ◽  
Zinc Transporter ◽  
Zinc Transport ◽  
Efflux Transporter ◽  
Cation Diffusion ◽  
Transporter Family ◽  
Slc30 Family ◽  
Solute Carrier ◽  
And Function

A growing body of evidence continues to demonstrate the vital roles that zinc and its transporters play on human health. The solute carrier (SLC) 30 and 39 families, with ten and fourteen members, respectively, control zinc transport in cells. TMEM163, a recently characterized zinc transporter, has similar characteristics in both structure and function to the SLC30 family. This review examines recent data that reveal TMEM163 to be a zinc efflux transporter and a new member of the cation diffusion facilitator (CDF) family of mammalian zinc transporter (ZNT) proteins. It also discusses reports that implicate TMEM163 in various human diseases.

Structural and functional studies of SAV1707 from Staphylococcus aureus elucidate its distinct metal-dependent activity and a crucial residue for catalysis

2021 ◽  
Vol 77 (5) ◽  
pp. 587-598
Author(s):  
Dong-Gyun Kim ◽  
Kyu-Yeon Lee ◽  
Sang Jae Lee ◽  
Seung-Ho Cheon ◽  
Yuri Choi ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Metal Binding ◽  
Binding Mode ◽  
Structure And Function ◽  
Functional Study ◽  
Functional Studies ◽  
Dependent Endonuclease ◽  
Metal Selectivity ◽  
Metal Binding Domain ◽  
And Function

The metallo-β-lactamase fold is the most abundant metal-binding domain found in two major kingdoms: bacteria and archaea. Despite the rapid growth in genomic information, most of these enzymes, which may play critical roles in cellular metabolism, remain uncharacterized in terms of structure and function. In this study, X-ray crystal structures of SAV1707, a hypothetical metalloenzyme from Staphylococcus aureus, and its complex with cAMP are reported at high resolutions of 2.05 and 1.55 Å, respectively, with a detailed atomic description. Through a functional study, it was verified that SAV1707 has Ni2+-dependent phosphodiesterase activity and Mn2+-dependent endonuclease activity, revealing a different metal selectivity depending on the reaction. In addition, the crystal structure of cAMP-bound SAV1707 shows a unique snapshot of cAMP that reveals the binding mode of the intermediate, and a key residue Phe511 that forms π–π interactions with cAMP was verified as contributing to substrate recognition by functional studies of its mutant. Overall, these findings characterized the relationship between the structure and function of SAV1707 and may provide further understanding of metalloenzymes possessing the metallo-β-lactamase fold.

scholarly journals Tungstoenzymes: Occurrence, Catalytic Diversity and Cofactor Synthesis

Inorganics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 44
Author(s):  
Carola S. Seelmann ◽  
Max Willistein ◽  
Johann Heider ◽  
Matthias Boll
Keyword(s):  
Abc Transporter ◽  
Aromatic Compounds ◽  
Metal Binding ◽  
Active Sites ◽  
Structure And Function ◽  
Hydration Reaction ◽  
Dimethyl Sulfoxide Reductase ◽  
Reduction Of Co2 ◽  
And Function ◽  
Electron Transfers

Tungsten is the heaviest element used in biological systems. It occurs in the active sites of several bacterial or archaeal enzymes and is ligated to an organic cofactor (metallopterin or metal binding pterin; MPT) which is referred to as tungsten cofactor (Wco). Wco-containing enzymes are found in the dimethyl sulfoxide reductase (DMSOR) and the aldehyde:ferredoxin oxidoreductase (AOR) families of MPT-containing enzymes. Some depend on Wco, such as aldehyde oxidoreductases (AORs), class II benzoyl-CoA reductases (BCRs) and acetylene hydratases (AHs), whereas others may incorporate either Wco or molybdenum cofactor (Moco), such as formate dehydrogenases, formylmethanofuran dehydrogenases or nitrate reductases. The obligately tungsten-dependent enzymes catalyze rather unusual reactions such as ones with extremely low-potential electron transfers (AOR, BCR) or an unusual hydration reaction (AH). In recent years, insights into the structure and function of many tungstoenzymes have been obtained. Though specific and unspecific ABC transporter uptake systems have been described for tungstate and molybdate, only little is known about further discriminative steps in Moco and Wco biosynthesis. In bacteria producing Moco- and Wco-containing enzymes simultaneously, paralogous isoforms of the metal insertase MoeA may be specifically involved in the molybdenum- and tungsten-insertion into MPT, and in targeting Moco or Wco to their respective apo-enzymes. Wco-containing enzymes are of emerging biotechnological interest for a number of applications such as the biocatalytic reduction of CO2, carboxylic acids and aromatic compounds, or the conversion of acetylene to acetaldehyde.

scholarly journals Structure and function of theLeptospira interrogansperoxide stress regulator (PerR), an atypical PerR devoid of a structural metal-binding site

2017 ◽  
Vol 293 (2) ◽  
pp. 497-509 ◽  
Author(s):  
Mounira Kebouchi ◽  
Frederick Saul ◽  
Raléb Taher ◽  
Annie Landier ◽  
Bénédicte Beaudeau ◽  
...  
Keyword(s):  
Binding Site ◽  
Metal Binding ◽  
Structure And Function ◽  
Metal Binding Site ◽  
Structural Metal ◽  
And Function

scholarly journals Essential Role for Zinc Transporter 2 (ZnT2)-mediated Zinc Transport in Mammary Gland Development and Function during Lactation

2015 ◽  
Vol 290 (21) ◽  
pp. 13064-13078 ◽  
Author(s):  
Sooyeon Lee ◽  
Stephen R. Hennigar ◽  
Samina Alam ◽  
Keigo Nishida ◽  
Shannon L. Kelleher
Keyword(s):  
Mammary Gland ◽  
Essential Role ◽  
Mammary Gland Development ◽  
Zinc Transporter ◽  
Zinc Transport ◽  
And Function ◽  
Gland Development

scholarly journals Critical Role of Transmembrane Segment Zinc Binding in the Structure and Function of Rhodopsin

2004 ◽  
Vol 279 (34) ◽  
pp. 35932-35941 ◽  
Author(s):  
Aleksandar Stojanovic ◽  
Jeremiah Stitham ◽  
John Hwa
Keyword(s):  
Critical Role ◽  
Structure And Function ◽  
Zinc Binding ◽  
Transmembrane Segment ◽  
And Function

scholarly journals Are Granulins Copper Sequestering Proteins?

2020 ◽  
Author(s):  
Anukool A. Bhopatkar ◽  
Vijayaraghavan Rangachari
Keyword(s):  
Metal Binding ◽  
Divalent Cations ◽  
Structure And Function ◽  
Proteolytic Processing ◽  
Reduced Form ◽  
Binding Potential ◽  
Stress Regulation ◽  
Ph Conditions ◽  
And Function ◽  
First Time

AbstractGranulins (GRN 1-7) are short (∼6 kDa), cysteine-rich proteins that are generated upon the proteolytic processing of progranulin (PGRN). These modules, along with their precursor, have been implicated in multiple pathophysiological roles, especially in neurodegenerative diseases. Our previous investigations into GRN-3 and GRN-5 reveal them to be fully disordered in the reduced form and implicate redox sensitive attributes to the proteins. Such redox-dependent modulation has become associated with proteins involved in oxidative stress regulation and maintaining metal-homeostasis within cells. To probe whether GRNs play a contributory role in such functions, we tested the metal binding potential of the reduced form of GRNs -3 and -5 under neutral and acidic pH mimicking cytosolic and lysosomal conditions, respectively. We found, at neutral pH, both GRNs selectively bind Cu(II) and no other divalent cations. Binding of Cu(II) also partly triggered the oxidative multimerization of GRNs via uncoordinated cystines at both pH conditions. Furthermore, binding did not induce gain in secondary structure and the protein remained disordered. Overall, the results indicate that GRN-3 and -5 have a surprisingly strong affinity for Cu(II) in the pM range, comparable to known copper sequestering proteins. This data also hints at a potential of GRNs to reduce Cu(II) to Cu(I), a process that has significance in mitigating Cu-induced ROS cytotoxicity in cells. Together, this report uncovers a metal-coordinating capability of GRNs for the first time, which could have profound significance in their structure and function.

scholarly journals Structural and Functional Changes in the Na+/H+ Exchanger Isoform 1, Induced by Erk1/2 Phosphorylation

2019 ◽  
Vol 20 (10) ◽  
pp. 2378 ◽  
Author(s):  
Larry Fliegel
Keyword(s):  
Amino Acid ◽  
Mammalian Cells ◽  
Ph Regulation ◽  
Specific Binding ◽  
Structure And Function ◽  
Membrane Domain ◽  
Functional Changes ◽  
Cytosolic Domain ◽  
And Function ◽  
Disordered Regions

The human Na+/H+ exchanger isoform 1 (NHE1) is a plasma membrane transport protein that plays an important role in pH regulation in mammalian cells. Because of the generation of protons by intermediary metabolism as well as the negative membrane potential, protons accumulate within the cytosol. Extracellular signal-regulated kinase (ERK)-mediated regulation of NHE1 is important in several human pathologies including in the myocardium in heart disease, as well as in breast cancer as a trigger for growth and metastasis. NHE1 has a N-terminal, a 500 amino acid membrane domain, and a C-terminal 315 amino acid cytosolic domain. The C-terminal domain regulates the membrane domain and its effects on transport are modified by protein binding and phosphorylation. Here, we discuss the physiological regulation of NHE1 by ERK, with an emphasis on the critical effects on structure and function. ERK binds directly to the cytosolic domain at specific binding domains. ERK also phosphorylates NHE1 directly at multiple sites, which enhance NHE1 activity with subsequent downstream physiological effects. The NHE1 cytosolic regulatory tail possesses both ordered and disordered regions, and the disordered regions are stabilized by ERK-mediated phosphorylation at a phosphorylation motif. Overall, ERK pathway mediated phosphorylation modulates the NHE1 tail, and affects the activity, structure, and function of this membrane protein.

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