Transient movement of helix F revealed by photo-induced inactivation by reaction of a bulky SH-reagent to cysteine-introduced pharaonis phoborhodopsin (Sensory rhodopsin II)

Hideaki Yoshida, Yuki Sudo, Kazumi Shimono, Masayuki Iwamoto, Naoki Kamo

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Pharaonis phoborhodopsin (ppR) is a photosensor of negative phototaxis in Natronomonas (Natronobacterium) pharaonis, an alkalophilic halophile. This protein has seven transmembrane helices into which a chromophore, all-trans retinal, binds to a specific lysine residue (located in helix G)via a protonated Schiff base. Various mutants were engineered to have a single cysteine in the F-helix. In the presence of a bulky fluorescent SH-reagent, MIANS, (2-(4′-maleimidylanilino)naphthalene-6-sulfonic acid, illumination decreased the photoreactivity or flash-yield (absorbance deflection immediately after the flash) of the L163C ppR mutant (in which Leu-163 was replaced with Cys) without changing the photocycling rate. The fluorescence of the isolated protein increased with increasing illumination. These observations suggest that during photocycling, the space around Cys-163 in the F-helix might open, permitting reaction with the relatively large molecule. This reaction occurred only at the M-state and not at the O-state. The implications are discussed.

Original languageEnglish
Pages (from-to)537-542
Number of pages6
JournalPhotochemical and Photobiological Sciences
Volume3
Issue number6
DOIs
Publication statusPublished - Jun 1 2004
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Fingerprint Dive into the research topics of 'Transient movement of helix F revealed by photo-induced inactivation by reaction of a bulky SH-reagent to cysteine-introduced pharaonis phoborhodopsin (Sensory rhodopsin II)'. Together they form a unique fingerprint.

  • Cite this