Document Detail


The N-terminal membrane occupation and recognition nexus domain of Arabidopsis phosphatidylinositol phosphate kinase 1 regulates enzyme activity.
MedLine Citation:
PMID:  17197438     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The type I B family of phosphatidylinositol phosphate kinases (PIPKs) contain a characteristic region of Membrane Occupation and Recognition Nexus (MORN) motifs at the N terminus. These MORN motifs are not found in PIPKs from other eukaryotes. To understand the impact of the additional N-terminal domain on protein function and subcellular distribution, we expressed truncated and full-length versions of AtPIPK1, one member of this family of PIPKs, in Escherichia coli and in tobacco cells grown in suspension culture. Deletion of the N-terminal MORN domain (amino acids 1-251) of AtPIPK1 increased the specific activity of the remaining C-terminal peptide (DeltaMORN) >4-fold and eliminated activation by phosphatidic acid (PtdOH). PtdOH activation could also be eliminated by mutating Pro(396) to Ala (P396A) in the predicted linker region between the MORN and the kinase homology domains. AtPIPK1 is product-activated and the MORN domain binds PtdIns(4,5)P(2). Adding back the MORN peptide to DeltaMORN or to the PtdOH-activated full-length protein increased activity approximately 2-fold. Furthermore, expressing the MORN domain in vivo increased the plasma membrane PtdInsP kinase activity. When cells were exposed to hyperosmotic stress, the MORN peptide redistributed from the plasma membrane to a lower phase or endomembrane fraction. In addition, endogenous PtdInsP kinase activity increased in the endomembrane fraction of hyperosmotically stressed cells. We conclude that the MORN peptide can regulate both the function and distribution of the enzyme in a manner that is sensitive to the lipid environment.
Authors:
Yang Ju Im; Amanda J Davis; Imara Y Perera; Eva Johannes; Nina S Allen; Wendy F Boss
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2006-12-29
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  282     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-02-19     Completed Date:  2007-04-17     Revised Date:  2008-08-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5443-52     Citation Subset:  IM    
Affiliation:
Plant Biology, North Carolina State University, Raleigh, North Carolina 27695-7649, USA.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Motifs / genetics
Arabidopsis / enzymology*,  genetics
Arabidopsis Proteins / genetics,  metabolism*
Cell Membrane / enzymology*,  genetics
Escherichia coli / enzymology,  genetics
Lipids / genetics
Phosphotransferases (Alcohol Group Acceptor) / genetics,  metabolism*
Protein Structure, Tertiary / genetics
Tobacco / enzymology,  genetics
Chemical
Reg. No./Substance:
0/Arabidopsis Proteins; 0/Lipids; EC 2.7.1.-/Phosphotransferases (Alcohol Group Acceptor); EC 2.7.1.67/phosphatidylinositol phosphate 4-kinase

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