Linked Life Data

16973620

Source:http://linkedlifedata.com/resource/pubmed/id/16973620

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
45
pubmed:dateCreated
2006-11-6
pubmed:abstractText
HMA2 is a Zn2+-ATPase from Arabidopsis thaliana. It contributes to the maintenance of metal homeostasis in cells by driving Zn2+ efflux. Distinct from P1B-type ATPases, plant Zn2+-ATPases have long C-terminal sequences rich in Cys and His. Removal of the 244 amino acid C terminus of HMA2 leads to a 43% reduction in enzyme turnover without significant effect on the Zn2+ K(1/2) for enzyme activation. Characterization of the isolated HMA2 C terminus showed that this fragment binds three Zn2+ with high affinity (Kd = 16 +/- 3 nM). Circular dichroism spectral analysis indicated the presence of 8% alpha-helix, 45% beta-sheet, and 48% random coil in the C-terminal peptide with noticeable structural changes upon metal binding (8% alpha-helix, 39% beta-sheet, and 52% random coil). Zn K-edge XAS of Zn-C-MBD in the presence of one equivalent of Zn2+ shows that the average zinc complex formed is composed of three His and one Cys residues. Upon the addition of two extra Zn2+ ions per C-MBD, these appear coordinated primarily by His residues thus, suggesting that the three Zn2+ binding domains might not be identical. Modification of His residues with diethyl pyrocarbonate completely inhibited Zn2+ binding to the C terminus, pointing out the importance of His residues in Zn2+ coordination. In contrast, alkylation of Cys with iodoacetic acid did not prevent Zn2+ binding to the HMA2 C terminus. Zn K-edge XAS of the Cys-alkylated protein was consistent with (N/O)4 coordination of the zinc site, with three of those ligands fitting for His residues. In summary, plant Zn2+-ATPases contain novel metal binding domains in their cytoplasmic C terminus. Structurally distinct from the well characterized N-terminal metal binding domains present in most P1B-type ATPases, they also appear to regulate enzyme turnover rate.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
281
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
33881-91
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed-meshheading:16973620-Absorptiometry, Photon, pubmed-meshheading:16973620-Adenosine Triphosphatases, pubmed-meshheading:16973620-Amino Acid Sequence, pubmed-meshheading:16973620-Arabidopsis, pubmed-meshheading:16973620-Arabidopsis Proteins, pubmed-meshheading:16973620-Carrier Proteins, pubmed-meshheading:16973620-Cell Membrane, pubmed-meshheading:16973620-Circular Dichroism, pubmed-meshheading:16973620-Cysteine, pubmed-meshheading:16973620-Enzyme Stability, pubmed-meshheading:16973620-Histidine, pubmed-meshheading:16973620-Kinetics, pubmed-meshheading:16973620-Molecular Sequence Data, pubmed-meshheading:16973620-Protein Binding, pubmed-meshheading:16973620-Protein Structure, Tertiary, pubmed-meshheading:16973620-Saccharomyces cerevisiae, pubmed-meshheading:16973620-Sequence Homology, Amino Acid, pubmed-meshheading:16973620-Sulfhydryl Compounds, pubmed-meshheading:16973620-Zinc
pubmed:year
2006
pubmed:articleTitle
A novel regulatory metal binding domain is present in the C terminus of Arabidopsis Zn2+-ATPase HMA2.
pubmed:affiliation
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, N.I.H., Extramural