HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 281, Issue 12, 7737-7746, March 24, 2006

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 281/12/7737    most recent M513052200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schiller, D. Articles by Morbach, S. Search for Related Content PubMed PubMed Citation Articles by Schiller, D. Articles by Morbach, S. Social Bookmarking                      What's this?

Influence of Membrane Composition on Osmosensing by the Betaine Carrier BetP from Corynebacterium glutamicum^*

Dirk Schiller, Vera Ott, Reinhard Krämer, and Susanne Morbach¹

From the Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706-1544 and the Institut für Biochemie, Universität zu Köln, Zülpicher Strasse 47, 50674 Köln, Germany

The glycine betaine carrier BetP from Corynebacterium glutamicum was recently shown to function as both an osmosensor and osmoregulator in proteoliposomes made from Escherichia coli phospholipids by sensing changes in the internal K⁺ concentration as a measure of hyperosmotic stress (Rübenhagen, R., Morbach, S., and Krämer, R. (2001) EMBO J. 20, 5412–5420). Furthermore, evidence was provided that a stretch of 25 amino acids of the C-terminal domain of BetP is critically involved in K⁺ sensing. This K⁺-sensitive region has been further characterized. Glu⁵⁷² turned out to be important for osmosensing in E. coli cells and in proteoliposomes made from E. coli phospholipids. BetP mutants E572K, E572P, and E572A/H573A/R574A were unable to detect an increase in the internal K⁺ concentration in this membrane environment. However, these BetP variants regained their ability to detect osmotic stress in membranes with increased phosphatidylglycerol content, i.e. in intact C. glutamicum cells or in proteoliposomes mimicking the composition of the C. glutamicum membrane. Mutants E572P and Y550P were still insensitive to osmotic stress also in this membrane background. These results led to the following conclusions. (i) The K⁺ sensor in mutants E572Q, E572D, and E572K is only partially impaired. (ii) Restoration of activity regulation is not possible if the correct conformation or orientation of the C-terminal domain is compromised by a proline residue at position 572 or 550. (iii) Phosphatidylglycerol in the membrane of C. glutamicum seems to stabilize the inactive conformation of BetP C252T and other mutants.

Received for publication, December 7, 2005 , and in revised form, January 13, 2006.

^* This work was supported by Deutsche Forschungsgemeinschaft Grant SPP 1070. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1–S4.

¹ To whom correspondence should be addressed. Tel.: 49-221-470-6464; Fax: 49-221-470-5091; E-mail: s.morbach{at}uni-koeln.de.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				N. Ozcan, C. S. Ejsing, A. Shevchenko, A. Lipski, S. Morbach, and R. Kramer Osmolality, Temperature, and Membrane Lipid Composition Modulate the Activity of Betaine Transporter BetP in Corynebacterium glutamicum J. Bacteriol., October 15, 2007; 189(20): 7485 - 7496. [Abstract] [Full Text] [PDF]

				P. Zimmann, A. Steinbrugge, M. Schniederberend, K. Jung, and K. Altendorf The Extension of the Fourth Transmembrane Helix of the Sensor Kinase KdpD of Escherichia coli Is Involved in Sensing J. Bacteriol., October 15, 2007; 189(20): 7326 - 7334. [Abstract] [Full Text] [PDF]

				A. Tondervik and A. R. Strom Membrane topology and mutational analysis of the osmotically activated BetT choline transporter of Escherichia coli Microbiology, March 1, 2007; 153(3): 803 - 813. [Abstract] [Full Text] [PDF]

				J. M. Wood Osmosensing by Bacteria Sci. Signal., October 17, 2006; 2006(357): pe43 - pe43. [Abstract] [Full Text] [PDF]

				N. A. B. N. Mahmood, E. Biemans-Oldehinkel, J. S. Patzlaff, G. K. Schuurman-Wolters, and B. Poolman Ion Specificity and Ionic Strength Dependence of the Osmoregulatory ABC Transporter OpuA J. Biol. Chem., October 6, 2006; 281(40): 29830 - 29839. [Abstract] [Full Text] [PDF]