Identification of Ion-Selectivity Determinants in Heavy-Metal Transport P1B-type ATPases

Identification of Ion-Selectivity Determinants in Heavy-Metal Transport P1B-type ATPases 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 PII-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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Identification of Ion-Selectivity Determinants in Heavy-Metal Transport P1B-type ATPases

Loading next page...
 
/lp/springer_journal/identification-of-ion-selectivity-determinants-in-heavy-metal-cW0F3OKX70
Publisher
Springer-Verlag
Copyright
Copyright © 2003 by Springer-Verlag New York Inc.
Subject
Philosophy
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-003-2048-2
Publisher site
See Article on Publisher Site

Abstract

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 PII-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.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Oct 9, 2003

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off