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Titolo:
ELECTRON-TRANSFER FROM THE TETRAHEME CYTOCHROME TO THE SPECIAL PAIR IN THE RHODOPSEUDOMONAS-VIRIDIS REACTION-CENTER - EFFECT OF MUTATIONS OF TYROSINE L162
Autore:
DOHSE B; MATHIS P; WACHTVEITL J; LAUSSERMAIR E; IWATA S; MICHEL H; OESTERHELT D;
Indirizzi:
MAX PLANCK INST BIOCHEM,MEMBRANBIOCHEM ABT D-82152 MARTINSRIED GERMANY MAX PLANCK INST BIOCHEM,MEMBRANBIOCHEM ABT D-82152 MARTINSRIED GERMANY CEA SACLAY,BIOENERGET SECT,CNRS,URA 1290 F-91191 GIF SUR YVETTE FRANCE UNIV MUNICH,INST MED OPT D-80797 MUNICH GERMANY MAX PLANCK INST BIOPHYS,MOLEK MEMBRANBIOL ABT D-60528 FRANKFURT GERMANY
Titolo Testata:
Biochemistry
fascicolo: 36, volume: 34, anno: 1995,
pagine: 11335 - 11343
SICI:
0006-2960(1995)34:36<11335:EFTTCT>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHOTOSYNTHETIC REACTION-CENTER; PHOTOOXIDIZED BACTERIOCHLOROPHYLL DIMER; L-SUBUNIT PLAYS; RHODOBACTER-SPHAEROIDES; MACROMOLECULAR CRYSTALLOGRAPHY; MEDIATED REREDUCTION; MOLECULAR-DYNAMICS; WEISSENBERG CAMERA; PROTEIN SUBUNITS; C PEROXIDASE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
45
Recensione:
Indirizzi per estratti:
Citazione:
B. Dohse et al., "ELECTRON-TRANSFER FROM THE TETRAHEME CYTOCHROME TO THE SPECIAL PAIR IN THE RHODOPSEUDOMONAS-VIRIDIS REACTION-CENTER - EFFECT OF MUTATIONS OF TYROSINE L162", Biochemistry, 34(36), 1995, pp. 11335-11343

Abstract

The structure of the photosynthetic reaction center (RC) from Rhodopseudomonas viridis is known to high resolution. It contains a firmly bound tetraheme cytochrome from which electrons are donated to a specialpair (P) of bacteriochlorophylls, which is photooxidized upon absorption of light. Tyrosine at position 162 of the L-subunit of the reaction center (L 162 Y) is a highly conserved residue positioned halfway between P and the proximal heme group (c-559) of the cytochrome. By specific mutagenesis this residue was exchanged against the amino acids phenylalanine 0, glycine (G), methionine (M), leucine (L), tryptophan (W), threonine (T), and histidine (H). All mutants were expressed in Rps. viridis using a recently established transformation system [Laussermair & Oesterhelt (1992) EMBO J. 11, 777-783]. They were shown biochemically to synthesize all four subunits of the RC (cytochrome, subunits L, M, and H) and to assemble them correctly into the membrane. The structures of two mutants (L 162 F and L 162 T) were determined and foundnot to differ significantly from the wild-type structure. All mutantsgrew photosynthetically. The absorption spectrum of all the mutants is the same as in WT, but the redox potential of P and of c-559 was changed by the mutations. The kinetics of electron transfer from the hemegroup to the special pair were measured in chromatophores by flash absorption. As found earlier in the wild type (Y) several exponential components were needed to fit the data. For the dominant fastest phase, the half-time varies from 147 to 1000 ns, in the order M, F, Y, W, H, L, G, T. We conclude that the tyrosine residue at position L 162 is not required for fast electron transfer from c-559 to P+.

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Documento generato il 15/07/20 alle ore 08:41:37