Skip Navigation


Plant and Cell Physiology Advance Access originally published online on April 22, 2007
Plant and Cell Physiology 2007 48(6):792-803; doi:10.1093/pcp/pcm046
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
48/6/792    most recent
pcm046v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (1)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Gorecka, K. M.
Right arrow Articles by Pikula, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gorecka, K. M.
Right arrow Articles by Pikula, S.
Agricola
Right arrow Articles by Gorecka, K. M.
Right arrow Articles by Pikula, S.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2007. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org

Potential Role of Annexin AnnAt1 from Arabidopsis thaliana in pH-Mediated Cellular Response to Environmental Stimuli

Karolina M. Gorecka1, Cyril Thouverey1,2, Rene Buchet2 and Slawomir Pikula1,*

1Department of Biochemistry, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, PL-02093 Warsaw, Poland
2Université Lyon 1, UMR CNRS 5013, UFR de Chimie-Biochimie, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne, France

*Corresponding author: E-mail, s.pikula{at}nencki.gov.pl; Fax, + 4822-822-5342.


  Abstract

Plant annexins, Ca2+- and membrane-binding proteins, are probably implicated in the cellular response to stress resulting from acidification of cytosol. To understand how annexins can contribute to cellular ion homeostasis, we investigated the pH-induced changes in the structure and function of recombinant annexin AnnAt1 from Arabidopsis thaliana. The decrease of pH from 7.0 to 5.8 reduced the time of the formation of ion channels by AnnAt1 in artificial lipid membranes from 3.5 h to 15–20 min and increased their unitary conductance from 32 to 63 pS. These changes were accompanied by an increase in AnnAt1 hydrophobicity as revealed by hydrophobicity predictions, by an increase in fluorescence of 2-(p-toluidino)naphthalene-6-sulfonic acid (TNS) bound to AnnAt1 and fluorescence resonance energy transfer from AnnAt1 tryptophan residues to TNS. Concomitant lipid partition of AnnAt1 at acidic pH resulted in its partial protection from proteolytic digestion. Secondary structures of AnnAt1 determined by circular dichroism and infrared spectroscopy were also affected by lowering the pH from 7.2 to 5.2. These changes were characterized by an increase in ß-sheet content at the expense of {alpha}-helical structures, and were accompanied by reversible formation of AnnAt1 oligomers as probed by ultracentrifugation in a sucrose gradient. A further decrease of pH from 5.2 to 4.5 or lower led to the formation of irreversible aggregates and loss of AnnAt1 ionic conductance. Our findings suggest that AnnAt1 can sense changes of the pH milieu over the pH range from 7 to 5 and respond by changes in ion channel conductance, hydrophobicity, secondary structure of the protein and formation of oligomers. Further acidification irreversibly inactivated AnnAt1. We suggest that the pH-sensitive ion channel activity of AnnAt1 may play a role in intracellular ion homeostasis.

Keywords: Annexins - Arabidopsis thaliana - Environmental response - Ion homeostasis - pH-induced ion channels

Abbreviations: AnnAt, annexin from A. thaliana; AnxA, verterbrate annexin; BSA, bovine serum albumin; IPTG, isopropyl-ß-D-thiogalactopyranoside; ROS, reactive oxygen species; TNS, 2-(p-toluidino)naphthalene-6-sulfonic acid.

(Received January 16, 2007; Accepted April 17, 2007)
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.