The role of surface-exposed Tyr-83 of plastocyanin in electron transfer from cytochrome c

Modi, Sandeep; He, Shiping; Gray, John C.; Bendall, Derek S.

doi:10.1016/0167-4838(92)90467-r

Cited by 55 publications

(50 citation statements)

References 34 publications

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“…5 indicate a decrease of the rate constant with the Y83L-plastocyanin by a factor of 1.7 relative to wild-type plastocyanin. This is significantly different from published data (24,27), which indicated a decrease of the second-order rate constant by the factor of 40 after this mutation. Thus, in our experiments with an intact homologous cyt bf complex, the effect of the Leu residue is rather small and that of Arg is in line with the changed charges.…”

Section: Does Tyr-83 Play a Significant Role In The Electroncontrasting

confidence: 99%

“…Site of Electron Transfer-The electron transfer path between cyt f and plastocyanin has been proposed to include Tyr-83 of plastocyanin (20,21,24,25,27). However, in contrast to previous results with a Y83L mutant, we did not find a decrease of the second-order rate constant relative to wild-type plastocyanin by a factor of 40 but only by a factor not higher than 1.7 at 90 mM NaCl.…”

Section: Does Tyr-83 Play a Significant Role In The Electroncontrasting

confidence: 99%

“…At 25°C the value of the rate constant is 62 ϫ 10 6 M Ϫ1 s Ϫ1 in the presence of 150 mM NaCl. Assuming the same ionic strength dependence of the reaction rate at 5 (see below) and 25°C, this value extrapolates to a rate constant of 185 ϫ 10 6 M Ϫ1 s Ϫ1 at 90 mM NaCl, which is by a factor of 4 faster than that reported for truncated cyt f under these conditions (24,25,27) but comparable to the value of 100 ϫ 10 6 M Ϫ1 s Ϫ1 found recently (29). To analyze the surface regions of plastocyanin involved in the rate-limiting step of the reaction with the cyt bf complex, the role of residues in the hydrophobic and acidic patches of spinach plastocyanin was probed using site-directed mutagenesis.…”

Section: Resultsmentioning

confidence: 53%

“…A substitution of Leu-12 in the hydrophobic patch (25) by Asn and Glu was found to accelerate and slow down the second-order rate constant, respectively, a finding that is not fully understood but may suggest a role of this site. For the interaction with truncated, soluble cyt f, it is widely accepted that the electron is transferred to the copper center of plastocyanin via Tyr-83 (20,24,25,27), which seems to be favored by the high electron density at the thiolate of the copper ligand Cys-84 (31).…”

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confidence: 99%

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Dynamic Interaction of Plastocyanin with the Cytochrome bf Complex

Illerhaus

Altschmied

Reichert

et al. 2000

Journal of Biological Chemistry

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The interaction between plastocyanin and the intact cytochrome bf complex, both from spinach, has been studied by stopped-flow kinetics with mutant plastocyanin to elucidate the site of electron transfer and the docking regions of the molecule. Mutation of Tyr-83 to Arg or Leu provides no evidence for a second electron transfer path via Tyr-83 of plastocyanin, which has been proposed to be the site of electron transfer from cytochrome f. The data found with mutations of acidic residues indicate that both conserved negative patches are essential for the binding of plastocyanin to the intact cytochrome bf complex. Replacing Ala-90 and Gly-10 at the flat hydrophobic surface of plastocyanin by larger residues slowed down and accelerated, respectively, the rate of electron transfer as compared with wild-type plastocyanin. These opposing effects reveal that the hydrophobic region around the electron transfer site at His-87 is divided up into two regions, of which only that with Ala-90 contributes to the attachment to the cytochrome bf complex. These binding sites of plastocyanin are substantially different from those interacting with photosystem I. It appears that each of the two binding regions of plastocyanin is split into halves, which are used in different combinations in the molecular recognition at the two membrane complexes.

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Section: Does Tyr-83 Play a Significant Role In The Electroncontrasting

confidence: 99%

Section: Does Tyr-83 Play a Significant Role In The Electroncontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 53%

mentioning

confidence: 99%

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Dynamic Interaction of Plastocyanin with the Cytochrome bf Complex

Illerhaus

Altschmied

Reichert

et al. 2000

Journal of Biological Chemistry

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“…Sixth, an important feature of plastocyanin is the presence of a negative patch at position 58-60, which is completely absent in azurin and amicyanin~Colman et al, 1978;Guss & Freeman, 1983;Meyer et al, 1993!. This negative patch is known to be a recognition or binding site between cytochrome f and plastocyaniñ He et al, 1991;Modi et al, 1992aModi et al, , 1992b!. In auracyanin, the possible role of a similar patch may be fulfilled by the two glutamic acid residues located at positions 58 and 60, although we should be aware that the correspondence with the upper patch in plastocyanin may be coincidental.…”

Section: Comparison Of Auracyanin a To Other Small Blue Copper Proteinsmentioning

confidence: 99%

Auracyanin a from the thermophilic green gliding photosynthetic bacterium chloroflexus aurantiacus represents an unusual class of small blue copper proteins

Driessche

Werken

et al. 1999

Protein Science

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The amino acid sequence of the small copper protein auracyanin A isolated from the thermophilic photosynthetic green bacterium Chloroflexus aurantiacus has been determined to be a polypeptide of 139 residues. His58, Cys123, His128, and Met132 are spaced in a way to be expected if they are the evolutionary conserved metal ligands as in the known small copper proteins plastocyanin and azurin. Secondary structure prediction also indicates that auracyanin has a general b-barrel structure similar to that of azurin from Pseudomonas aeruginosa and plastocyanin from poplar leaves. However, auracyanin appears to have sequence characteristics of both small copper protein sequence classes. The overall similarity with a consensus sequence of azurin is roughly the same as that with a consensus sequence of plastocyanin, namely 30.5%. We suggest that auracyanin A, together with the B forms, is the first example of a new class of small copper proteins that may be descendants of an ancestral sequence to both the azurin proteins occurring in prokaryotic nonphotosynthetic bacteria and the plastocyanin proteins occurring in both prokaryotic cyanobacteria and eukaryotic algae and plants. The N-terminal sequence region 1-18 of auracyanin is remarkably rich in glycine and hydroxy amino acids, and required mass spectrometric analysis to be determined. The nature of the blocking group X is not yet known, although its mass has been determined to be 220 Da. The auracyanins are the first small blue copper proteins found and studied in anoxygenic photosynthetic bacteria and are likely to mediate electron transfer between the cytochrome bc 1 complex and the photosynthetic reaction center.

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Interactions in Plastocyanin−Lysine Peptide and Related Systems

Hirota

Yamauchi

2002

Eur. J. Inorg. Chem.

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The structure−function relationship of proteins is one of the major topics of protein studies. In spite of the importance of intermolecular interactions between proteins, which could control their functions, there are only a limited number of detailed studies on the protein structural changes induced by interaction with a protein or a peptide, because the associated changes in properties are small. Charged peptides, however, may be useful for studying the molecular recognition character of proteins and their interaction-induced struc-

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The role of surface-exposed Tyr-83 of plastocyanin in electron transfer from cytochrome c

Cited by 55 publications

References 34 publications

Dynamic Interaction of Plastocyanin with the Cytochrome bf Complex

Dynamic Interaction of Plastocyanin with the Cytochrome bf Complex

Auracyanin a from the thermophilic green gliding photosynthetic bacterium chloroflexus aurantiacus represents an unusual class of small blue copper proteins

Interactions in Plastocyanin−Lysine Peptide and Related Systems

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