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

J. Biol. Chem., Vol. 281, Issue 45, 34239-34245, November 10, 2006

This Article Full Text Full Text (PDF) All Versions of this Article: 281/45/34239    most recent M605907200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted 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 Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sudo, Y. Articles by Spudich, J. L. Search for Related Content PubMed PubMed Citation Articles by Sudo, Y. Articles by Spudich, J. L. Social Bookmarking                      What's this?

Functional Importance of the Interhelical Hydrogen Bond between Thr²⁰⁴ and Tyr¹⁷⁴ of Sensory Rhodopsin II and Its Alteration during the Signaling Process^*

Yuki Sudo, Yuji Furutani^¶, Hideki Kandori^¶, and John L. Spudich¹

From the Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, Texas 77030, Department of Materials Science and Engineering, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan, and ^¶Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Kyoto 606-8502, Japan

Sensory rhodopsin II (SRII), a receptor for negative phototaxis in haloarchaea, transmits light signals through changes in protein-protein interaction with its transducer HtrII. Light-induced structural changes throughout the SRII-HtrII interface, which spans the periplasmic region, membrane-embedded domains, and cytoplasmic domains near the membrane, have been identified by several studies. Here we demonstrate by site-specific mutagenesis and analysis of phototaxis behavior that two residues in SRII near the membrane-embedded interface (Tyr¹⁷⁴ on helix F and Thr²⁰⁴ on helix G) are essential for signaling by the SRII-HtrII complex. These residues, which are the first in SRII shown to be required for phototaxis function, provide biological significance to the previous observation that the hydrogen bond between them is strengthened upon the formation of the earliest SRII photointermediate (SRII_K) only when SRII is complexed with HtrII. Here we report frequency changes of the S-H stretch of a cysteine substituted for SRII Thr²⁰⁴ in the signaling state intermediates of the SRII photocycle, as well as an influence of HtrII on the hydrogen bond strength, supporting a direct role of the hydrogen bond in SRII-HtrII signal relay chemistry. Our results suggest that the light signal is transmitted to HtrII from the energized interhelical hydrogen bond between Thr²⁰⁴ and Tyr¹⁷⁴, which is located at both the retinal chromophore pocket and in helices F and G that form the membrane-embedded interaction surface to the signal-bearing second transmembrane helix of HtrII. The results argue for a critical process in signal relay occurring at this membrane interfacial region of the complex.

Received for publication, June 20, 2006 , and in revised form, August 28, 2006.

^* This work was supported by National Institutes of Health Grant R37GM27750 and a Robert A. Welch Foundation endowment (to J. L. S.). 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.

¹ To whom correspondence should be addressed. Tel.: 713-500-5473; Fax: 713-500-0545; E-mail: John.L.Spudich{at}uth.tmc.edu.

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

This article has been cited by other articles:

				T. Kitajima-Ihara, Y. Furutani, D. Suzuki, K. Ihara, H. Kandori, M. Homma, and Y. Sudo Salinibacter Sensory Rhodopsin: SENSORY RHODOPSIN I-LIKE PROTEIN FROM A EUBACTERIUM J. Biol. Chem., August 29, 2008; 283(35): 23533 - 23541. [Abstract] [Full Text] [PDF]

				Y. Sudo, Y. Furutani, J. L. Spudich, and H. Kandori Early Photocycle Structural Changes in a Bacteriorhodopsin Mutant Engineered to Transmit Photosensory Signals J. Biol. Chem., May 25, 2007; 282(21): 15550 - 15558. [Abstract] [Full Text] [PDF]