Document Detail

Identification of ion-selectivity determinants in heavy-metal transport P1B-type ATPases.
MedLine Citation:
PMID:  14692449     Owner:  NLM     Status:  MEDLINE    
P1B-type ATPases transport a variety of metals (Cd2+, Zn2+, Pb2+, Co2+, Cu2+, Ag+, Cu+) across biomembranes. Characteristic sequences CP[C/H/S] in transmembrane fragment H6 were observed in the putative transporting metal site of the founding members of this subfamily (initially named CPx-ATPases). In spite of their importance for metal homeostasis and biotolerance, their mechanisms of ion selectivity are not understood. Studies of better-characterized P(II)-type ATPases (Ca-ATPase and Na,K-ATPase) have identified three transmembrane segments that participate in ion binding and transport. Testing the hypothesis that metal specificity is determined by conserved amino acids located in the equivalent transmembrane segments of P1B-type ATPases (H6, H7, and H8), 234 P1B-ATPase protein sequences were analyzed. This showed that although H6 contains characteristic CPX or XPC sequences, conserved amino acids in H7 and H8 provide signature sequences that predict the metal selectivity in each of five P1B-ATPase subgroups identified. These invariant amino acids contain diverse side chains (thiol, hydroxyl, carbonyl, amide, imidazolium) that can participate in transient metal coordination during transport and consequently determine the particular metal selectivity of each enzyme. Each subgroup shares additional structural characteristics such as the presence (or absence) of particular amino-terminal metal-binding domains and the number of putative transmembrane segments. These differences suggest unique functional characteristics for each subgroup in addition to their particular metal specificity.
J M Argüello
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of membrane biology     Volume:  195     ISSN:  0022-2631     ISO Abbreviation:  J. Membr. Biol.     Publication Date:  2003 Sep 
Date Detail:
Created Date:  2003-12-24     Completed Date:  2004-05-04     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0211301     Medline TA:  J Membr Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  93-108     Citation Subset:  IM    
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Rd., Worcester, MA 01609, USA.
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MeSH Terms
Adenosine Triphosphatases / chemistry*
Amino Acid Sequence
Biological Transport
Metals, Heavy / metabolism*
Molecular Sequence Data
Protein Conformation
Sequence Homology, Amino Acid
Grant Support
Reg. No./Substance:
0/Metals, Heavy; EC 3.6.1.-/Adenosine Triphosphatases

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