Document Detail


Regulation and function of lysine-substituted Na,K pumps in salt adaptation of Artemia franciscana.
MedLine Citation:
PMID:  18074167     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The brine shrimp Artemia thrives at extreme conditions of up to 300 g/l salt in hypersaline lakes, but the molecular aspects of this salt adaptation are not clarified. To examine the influence of salt on the expression of two isoforms of Na,K-ATPase, adult Artemia franciscana were cultured for 39 days with the microalga Dunaliella salina as fodder at increasing salt from 30 to 280 g/l. Quantitative reverse-transcriptase polymerase chain reaction showed that the abundance of mRNA of the lysine-substituted alpha(2)(KK)-subunit was very low at 30 g/l salt but rose steeply in the range of 70-200 g/l to a level at 200-280 g/l salt, similar to the abundance of the mRNA of the alpha(1)(NN)-subunit, which was insignificantly affected by increasing salt. Site-directed mutagenesis showed that Asn324Lys and Asn776Lys in the alpha(1)-subunit of pig kidney Na,K-ATPase reduced the stoichiometry of (204)Tl binding from 2 to about 1 Tl(+)(K(+)) per alpha-subunit and Na(+)-dependent phosphorylation from ATP to 25-30%. In structure models, the epsilon-amino group of Lys776 is located at cation site 1 in the E(1)P form and near cation site 2 in the E(2) conformation, while the side chain of Lys324 points away from the cation sites. Salt-induced expression of the alpha(2)(KK)-subunit Na,K-ATPase in A. franciscana may reduce the Na(+)/ATP ratio and enable the Na,K pump to extrude Na(+) against steeper gradients and, thus, contribute to salt adaptation.
Authors:
Peter Leth Jorgensen; Francisco Amat
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-12-12
Journal Detail:
Title:  The Journal of membrane biology     Volume:  221     ISSN:  0022-2631     ISO Abbreviation:  J. Membr. Biol.     Publication Date:  2008 Jan 
Date Detail:
Created Date:  2008-01-11     Completed Date:  2008-05-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0211301     Medline TA:  J Membr Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  39-49     Citation Subset:  IM    
Affiliation:
Department of Molecular Biology, University of Copenhagen, Universitetsparken 13, Copenhagen OE, Denmark. pljorgensen@aki.ku.dk
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological / drug effects*,  genetics
Amino Acid Substitution
Animals
Artemia / enzymology*,  genetics
Gene Expression Regulation, Enzymologic / drug effects
Lysine / genetics
Models, Molecular
Mutagenesis, Site-Directed
Protein Binding
Protein Structure, Secondary
Protein Structure, Tertiary
Protein Subunits / chemistry,  genetics,  metabolism
RNA, Messenger / genetics,  metabolism
Reverse Transcriptase Polymerase Chain Reaction
Sodium Chloride / pharmacology*
Sodium-Potassium-Exchanging ATPase / chemistry,  genetics*,  metabolism
Structure-Activity Relationship
Chemical
Reg. No./Substance:
0/Protein Subunits; 0/RNA, Messenger; 56-87-1/Lysine; 7647-14-5/Sodium Chloride; EC 3.6.3.9/Sodium-Potassium-Exchanging ATPase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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