Participation of the surface structure of Pharaonis phoborhodopsin, ppR and its A149S and A149V mutants, consisting of the C-terminal α-helix and E-F loop, in the complex-formation with the cognate transducer pHtrII, as revealed by site-directed 13C solid-state NMR

Izuru Kawamura, Yoichi Ikeda, Yuki Sudo, Masayuki Iwamoto, Kazumi Shimono, Satoru Yamaguchi, Satoru Tuzi, Hazime Saitô, Naoki Kamo, Akira Naito

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We have recorded 13C solid state NMR spectra of [3- 13C]Ala-labeled pharaonis phoborhodopsin (ppR) and its mutants, A149S and A149V, complexed with the cognate transducer pharaonis halobacterial transducer II protein (pHtrII) (1-159), to gain insight into a possible role of their cytoplasmic surface structure including the C-terminal α-helix and E-F loop for stabilization of the 2:2 complex, by both cross-polarization magic angle spinning (CP-MAS) and dipolar decoupled (DD)-MAS NMR techniques. We found that 13C CP-MAS NMR spectra of [3-13C]Ala-ppR, A149S and A149V complexed with the transducer pHtrII are very similar, reflecting their conformation and dynamics changes caused by mutual interactions through the transmembrane α-helical surfaces. In contrast, their DD-MAS NMR spectral features are quite different between [3-13C]Ala- A149S and A149V in the complexes with pHtrII: 13C DD-MAS NMR spectrum of [3- 13C]Ala-A149S complex is rather similar to that of the uncomplexed form, while the corresponding spectral feature of A149V complex is similar to that of ppR complex in the C-terminal tip region. This is because more flexible surface structure detected by the DD-MAS NMR spectra are more directly influenced by the dynamics changes than the CP-MAS NMR. It turned out, therefore, that an altered surface structure of A149S resulted in destabilized complex as viewed from the 13C NMR spectrum of the surface areas, probably because of modified conformation at the corner of the helix E in addition to the change of hydropathy. It is, therefore, concluded that the surface structure of ppR including the C-terminal α-helix and the E-F loops is directly involved in the stabilization of the complex through conformational stability of the helix E.

Original languageEnglish
Pages (from-to)339-345
Number of pages7
JournalPhotochemistry and Photobiology
Volume83
Issue number2
DOIs
Publication statusPublished - Mar 1 2007
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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