Biochemical and biophysical insights into the metal binding spectrum and bioactivity of arginase of Entamoeba histolytica

Metallomics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 623-638 ◽  
Author(s):  
Anjali Malik ◽  
Harvijay Singh ◽  
Akshay Pareek ◽  
Shailly Tomar
Keyword(s):  
Entamoeba Histolytica ◽  
Metal Binding ◽  
Metal Ion ◽  
Ion Selectivity ◽  
Divalent Metal ◽  
First Report ◽  
Divalent Metal Ion ◽  
Metal Ion Selectivity

First report of the promiscuous nature of Entamoeba histolytica arginase for divalent metal ion selectivity.

scholarly journals Substrate Profile and Metal-ion Selectivity of Human Divalent Metal-ion Transporter-1

2012 ◽  
Vol 287 (36) ◽  
pp. 30485-30496 ◽  
Author(s):  
Anthony C. Illing ◽  
Ali Shawki ◽  
Christopher L. Cunningham ◽  
Bryan Mackenzie
Keyword(s):  
Metal Ion ◽  
Ion Selectivity ◽  
Divalent Metal ◽  
Ion Transporter ◽  
Divalent Metal Ion ◽  
Metal Ion Selectivity

scholarly journals Substrate profile and metal‐ion selectivity of the human divalent metal‐ion transporter DMT1

2007 ◽  
Vol 21 (6) ◽  
Author(s):  
Anthony C Illing ◽  
Ali Shawki ◽  
Christopher L Cunningham ◽  
Bryan Mackenzie
Keyword(s):  
Metal Ion ◽  
Ion Selectivity ◽  
Divalent Metal ◽  
Ion Transporter ◽  
Divalent Metal Ion ◽  
Metal Ion Selectivity

scholarly journals HK97 gp74 Possesses an α-Helical Insertion in the ββα Fold That Affects Its Metal Binding, cos Site Digestion, and In Vivo Activities

2020 ◽  
Vol 202 (8) ◽  
Author(s):  
Sasha A. Weiditch ◽  
Sarah C. Bickers ◽  
Diane Bona ◽  
Karen L. Maxwell ◽  
Voula Kanelis
Keyword(s):  
Metal Binding ◽  
Metal Ion ◽  
Divalent Metal ◽  
Metal Ion Binding ◽  
Divalent Metal Ions ◽  
Nmr Studies ◽  
Phage Dna ◽  
Divalent Metal Ion ◽  
Phage Morphogenesis

ABSTRACT The last gene in the genome of the bacteriophage HK97 encodes gp74, an HNH endonuclease. HNH motifs contain two conserved His residues and an invariant Asn residue, and they adopt a ββα structure. gp74 is essential for phage head morphogenesis, likely because gp74 enhances the specific endonuclease activity of the HK97 terminase complex. Notably, the ability of gp74 to enhance the terminase-mediated cleavage of the phage cos site requires an intact HNH motif in gp74. Mutation of H82, the conserved metal-binding His residue in the HNH motif, to Ala abrogates gp74-mediated stimulation of terminase activity. Here, we present nuclear magnetic resonance (NMR) studies demonstrating that gp74 contains an α-helical insertion in the Ω-loop, which connects the two β-strands of the ββα fold, and a disordered C-terminal tail. NMR data indicate that the Ω-loop insert makes contacts to the ββα fold and influences the ability of gp74 to bind divalent metal ions. Further, the Ω-loop insert and C-terminal tail contribute to gp74-mediated DNA digestion and to gp74 activity in phage morphogenesis. The data presented here enrich our molecular-level understanding of how HNH endonucleases enhance terminase-mediated digestion of the cos site and contribute to the phage replication cycle. IMPORTANCE This study demonstrates that residues outside the canonical ββα fold, namely, the Ω-loop α-helical insert and a disordered C-terminal tail, regulate the activity of the HNH endonuclease gp74. The increased divalent metal ion binding when the Ω-loop insert is removed compared to reduced cos site digestion and phage formation indicates that the Ω-loop insert plays multiple regulatory roles. The data presented here provide insights into the molecular basis of the involvement of HNH proteins in phage DNA packing.

scholarly journals Multiple Metal Binding Domains Enhance the Zn(II) Selectivity of the Divalent Metal Ion Transporter AztA†

Biochemistry ◽  
2007 ◽  
Vol 46 (39) ◽  
pp. 11057-11068 ◽  
Author(s):  
Tong Liu ◽  
Hermes Reyes-Caballero ◽  
Chenxi Li ◽  
Robert A. Scott ◽  
David P. Giedroc
Keyword(s):  
Metal Binding ◽  
Metal Ion ◽  
Divalent Metal ◽  
Ion Transporter ◽  
Binding Domains ◽  
Divalent Metal Ion

scholarly journals A Single Serine Residue Determines Selectivity to Monovalent Metal Ions in Metalloregulators of the MerR Family

2015 ◽  
Vol 197 (9) ◽  
pp. 1606-1613 ◽  
Author(s):  
María M. Ibáñez ◽  
Susana K. Checa ◽  
Fernando C. Soncini
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Metal Ion ◽  
Target Genes ◽  
Divalent Metal ◽  
Serine Residue ◽  
Ion Sensors ◽  
Monovalent Metal ◽  
Divalent Metal Ion ◽  
Metal Ion Sensors

ABSTRACTMerR metalloregulators alleviate toxicity caused by an excess of metal ions, such as copper, zinc, mercury, lead, cadmium, silver, or gold, by triggering the expression of specific efflux or detoxification systems upon metal detection. The sensor protein binds the inducer metal ion by using two conserved cysteine residues at the C-terminal metal-binding loop (MBL). Divalent metal ion sensors, such as MerR and ZntR, require a third cysteine residue, located at the beginning of the dimerization (α5) helix, for metal coordination, while monovalent metal ion sensors, such as CueR and GolS, have a serine residue at this position. This serine residue was proposed to provide hydrophobic and steric restrictions to privilege the binding of monovalent metal ions. Here we show that the presence of alanine at this position does not modify the activation pattern of monovalent metal sensors. In contrast, GolS or CueR mutant sensors with a substitution of cysteine for the serine residue respond to monovalent metal ions or Hg(II) with high sensitivities. Furthermore, in a mutant deleted of the Zn(II) exporter ZntA, they also trigger the expression of their target genes in response to either Zn(II), Cd(II), Pb(II), or Co(II).IMPORTANCESpecificity in a stressor's recognition is essential for mounting an appropriate response. MerR metalloregulators trigger the expression of specific resistance systems upon detection of heavy metal ions. Two groups of these metalloregulators can be distinguished, recognizing either +1 or +2 metal ions, depending on the presence of a conserved serine in the former or a cysteine in the latter. Here we demonstrate that the serine residue in monovalent metal ion sensors excludes divalent metal ion detection, as its replacement by cysteine renders a pan-metal ion sensor. Our results indicate that the spectrum of signals detected by these sensors is determined not only by the metal-binding ligand availability but also by the metal-binding cavity flexibility.

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