title: Mutations in the ArsA ATPase that restore interaction with the ArsD metallochaperone.
abstract: The ArsA ATPase is the catalytic subunit of the ArsAB As(III) efflux pump. It receives trivalent As(III) from the intracellular metallochaperone ArsD. The interaction of ArsA and ArsD allows for resistance to As(III) at environmental concentrations. A quadruple mutant in the arsD gene encoding a K2A/K37A/K62A/K104A ArsD is unable to interact with ArsA. An error-prone mutagenesis approach was used to generate random mutations in the arsA gene that restored interaction with the quadruple arsD mutant in yeast two-hybrid assays. A number of arsA genes with multiple mutations were isolated. These were analyzed in more detail by separation into single arsA mutants. Three such mutants encoding Q56R, F120I and D137V ArsA were able to restore interaction with the quadruple ArsD mutant in yeast two-hybrid assays. Each of the three single ArsA mutants also interacted with wild type ArsD. Only the Q56R ArsA derivative exhibited significant metalloid-stimulated ATPase activity in vitro. Purified Q56R ArsA was stimulated by wild type ArsD and to a lesser degree by the quadruple ArsD derivative. The F120I and D137V ArsAs did not show metalloid-stimulated ATPase activity. Structural models generated by in silico docking suggest that an electrostatic interface favors reversible interaction between ArsA and ArsD. We predict that mutations in ArsA propagate changes in hydrogen bonding and salt bridges to the ArsA-ArsD interface that affect their interactions.
authors.affiliation: Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, 33199, USA.
authors.forename: Jitesh K
authors.initials: JK
authors.lastname: Pillai
authors.forename: Sarkarai
authors.initials: S
authors.lastname: Venkadesh
authors.forename: A Abdul
authors.initials: AA
authors.lastname: Ajees
authors.forename: Barry P
authors.initials: BP
authors.lastname: Rosen
authors.forename: Hiranmoy
authors.initials: H
authors.lastname: Bhattacharjee
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D019943:Amino Acid Substitution; D001151:Arsenic / Q000378:metabolism; D002384:Catalysis; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D016623:Ion Pumps / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D062105:Molecular Docking Simulation; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism; D016296:Mutagenesis; D020125:Mutation, Missense; D010957:Plasmids; D017354:Point Mutation; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: C558793:ArsD protein, E coli; D029968:Escherichia coli Proteins; D016623:Ion Pumps; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D000251:Adenosine Triphosphatases; C486481:ArsAB ATPase, E Coli; D001151:Arsenic