Portal de Periódicos da CAPES

Cation Hexaammines Are Selective and Potent Inhibitors of the CorA Magnesium Transport System

2000; Elsevier BV; Volume: 275; Issue: 22 Linguagem: Inglês

10.1074/jbc.m001507200

1083-351X

Lisa M. Kucharski, W. Lübbe, Michael E. Maguire,

Aluminum toxicity and tolerance in plants and animals

Cation hexaammines and related compounds are chemically stable analogs of the hydrated form of cations, particularly Mg 2+ . We tested the ability of several of these compounds to inhibit transport by the CorA or MgtB Mg 2+ transport systems or the PhoQ receptor kinase for Mg 2+ in Salmonella typhimurium . Cobalt(III)-, ruthenium(II)-, and ruthenium(III)-hexaammines were potent inhibitors of CorA-mediated influx. Cobalt(III)- and ruthenium(III)chloropentaammines were slightly less potent inhibitors of CorA. The compounds inhibited uptake by the bacterial S. typhimurium CorA and by the archaeal Methanococcus jannaschii CorA, which bear only 12% identity in the extracellular periplasmic domain. Cation hexaammines also inhibited growth of S. typhimurium strains dependent on CorA for Mg 2+ uptake but not of isogenic strains carrying a second Mg 2+ uptake system. In contrast, hexacyano-cobaltate(III) and ruthenate(II)- and nickel(II)hexaammine had little effect on uptake. The inhibition by the cation hexaammines was selective for CorA because none of the compounds had any effect on transport by the MgtB P-type ATPase Mg 2+ transporter or the PhoQ Mg 2+ receptor kinase. These results demonstrate that cation hexaammines are potent and highly selective inhibitors of the CorA Mg 2+ transport system and further indicate that the initial interaction of the CorA transporter is with a fully hydrated Mg 2+ cation.