Abstract
A site directed mutant of the Photosystem I reaction center of Chlamydomonas reinhardtii has been described previously. [Hallahan et al. (1995) Photosynth Res 46: 257–264]. The mutation, PsaA: D576L, changes the conserved aspartate residue adjacent to one of the cysteine ligands binding the Fe-SX center to PsaA. The mutation, which prevents photosynthetic growth, was observed to change the EPR spectrum of the Fe-SA/B centers bound to the PsaC subunit. We suggested that changes in binding of PsaC to the PsaA/PsaB reaction center prevented efficient electron transfer. Second site suppressors of the mutation have now been isolated which have recovered the ability to grow photosynthetically. DNA analysis of four suppressor strains showed the original D576L mutation is intact, and that no mutations are present elsewhere within the Fe-SX binding region of either PsaA or PsaB, nor within PsaC or PsaJ. Subsequent genetic analysis has indicated that the suppressor mutation(s) is nuclear encoded. The suppressors retain the altered binding of PsaC, indicating that this change is not the cause of failure to grow photosynthetically. Further analysis showed that the rate of electron transfer from the quinone electron carrier A1 to Fe-SX is slowed in the mutant (by a factor of approximately two) and restored to wild type rates in the suppressors. ENDOR spectra of A1 ·– in wild-type and mutant preparations are identical, indicating that the electronic structure of the phyllosemiquinone is not changed. The results suggest that the quinone to Fe-SX center electron transfer is sensitive to the structure of the iron-sulfur center, and may be a critical step in the energy conversion process. They also indicate that the structure of the reaction center may be modified as a result of changes in proteins outside the core of the reaction center.
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References
Boudreau E, Otis C and Turmel M (1994) Conserved gene clusters in the highly rearranged chloroplast genomes of Chlamydomonas moewusii and Chlamydomonas reinhardtii. Plant Mol Biol 24: 585–602
Boardman NK (1971) Sub-chloroplast fragments: Digitonin method. Methods Enzymol 23: 268–276
Brettel K (1997) Electron transfer and arrangement of the redox cofactors in Photosystem I. Biochim Biophys Acta 1318: 322–373
Delepelaire P and Chua N-H (1979) Lithium dodecyl sulfate/polyacrylamide gel electrophoresis of thylakoid membranes at 4 °C: Characterisation of two additional chlorophyll a-protein complexes. Proc Natl Acad Sci USA 76: 111–115
Diner BA and Wollman FA (1980) Isolation of highly active Photosystem II complexes of C. reinhardtii. Eur J Biochem 110: 521–526
Evans MCW, Hallahan BJ, Hanley JA, Heathcote P, Gumpel NJ and Purton S (1995) Isolation and characterization of photosynthetic reaction centers from eukaryotic organisms. In: Brown GC and Cooper CE (eds) Bioenergetics: A Practical Approach, pp 183–213. IRL Press, Oxford
Fish LE, Kuck U and Bogorad L (1985) Two partially homologous adjacent light inducible chloroplast genes encoding polypeptides of the P700 chlorophyll a protein complex of Photosystem 1. J Biol Chem 260: 1413–1421
Golbeck JH and Cornelius JM (1986) Photosystem I charge separation in the absence of Centers A and B. 1. Optical characterisation of Center ‘A2’ and evidence for its association with a 64 kDa peptide. Biochim Biophys Acta 549: 16–24
Hallahan BJ, Purton S, Ivison A, Wright D and Evans MCW (1995) Analysis of the proposed Fe-SX binding region of Photosystem I by site directed mutation of PsaA in Chlamydomonas reinhardtii. Photosynth Res 46: 257–264
Harris EH (1989) The Chlamydomonas Sourcebook. A Comprehensive Guide to Biology and Laboratory Use. Academic Press, San Diego, CA
Heathcote P, Hanley JA and Evans MCW (1993) Double-reduction of A1 abolishes the EPR signal attributed to A1 .- evidence for C2 symmetry in the Photosystem I reaction centre. Biochim Biophys Acta 1144: 56–61
Heathcote P, Moenne-Loccoz P, Rigby SEJ and Evans MCW (1996) Photoaccumulation in Photosystem I does produce a phylloquinone (A1 .) radical. Biochemistry 35: 6644–6650
Höj PB and Møller BL (1986) The 110 kDa reaction centre protein of Photosystem I, chlorophyll a-protein 1, is an iron-sulphur protein. J Biol Chem 261: 14292–14300
Höj PB, Svendsen IB, Scheller HV and Møller BL (1987) Identification of a chloroplast-encoded 9-kDa polypeptide as a 2[4Fe-4S] protein carrying centers a and b of Photosystem I. J Biol Chem 262: 12676–12684
Li N, Zhao JD, Warren PV, Warden JT, Bryant DA and Golbeck JH (1991) PsaD is required for the stable binding of PsaC to the Photosystem I core protein of Synechococcus-sp pcc-6301. Biochemistry 30: 7863–7872
Luneberg J, Fromme P, Jekow P and Schlodder E (1994) Spectroscopic characterization of Photosystem I core complexes from thermophilic Synechococcus sp. – identical reoxidation kinetics of A1 - before and after removal of the iron-sulfur-clusters FA and FB. FEBS Lett 338: 197–202
Moenne-Loccoz P, Heathcote P, Maclachlan DJ, Berry MC, Davis IH and Evans MCW (1994) The path of electron transfer in Photosystem I: Direct evidence of forward electron transfer from A1 to Fe-SX. Biochemistry 33: 10037–10042
Nugent JHA (1996) Oxygenic photosynthesis. Electron transfer in Photosystem I and Photosystem II. Eur J Biochem 237: 519–531
Rigby SEJ, Nugent JHA and O'Malley PJ (1994) The dark stable tyrosine radical of Photosystem 2 studied in three species using ENDOR and EPR spectroscopies. Biochemistry 33: 1734–1742
Rigby SEJ, Evans MCW, Heathcote P (1996) ENDOR and special triple resonance spectroscopy of A1 - of Photosystem I. Biochemistry 35: 6651–6656
Rochaix J-D, Mayfield S, Goldschmidt-Clermont M, Erickson J (1988) Molecular biology of Chlamydomonas. In: Shaw CH (ed) Plant Molecular Biology: A Practical Approach, pp 253–275. IRL Press, Oxford
Rodday SM, Webber AN, Bingham SE and Biggins J (1995) Evidence that the F-x domain in Photosystem I interacts with the subunit PsaC: Site-directed changes in PsaB destabilize the subunit interaction in Chlamydomonas reinhardtii. Biochemistry 34: 6328–6334
Schlodder E, Falkenberg K, Gergeleit M and Brettel K (1998) Temperature dependence of forward and reverse electron transfer from A1 .-, the reduced secondary electron acceptor in Photosystem I. Biochemistry 37: 9466–9476
Schubert WD, Klukas O, Krauss N, Saenger W, Fromme P and Witt HT (1997) Photosystem I of Synechococcus elongatus at 4 Å resolution: Comprehensive structure analysis. J Mol Biol 272: 741–769
Smart LB, Warren PV, Golbeck JH and McIntosh L (1993) Mutational analysis of the structure and biogenesis of the Photosystem-I reaction center in the cyanobacterium Synechocystis sp. Pcc-6803. Proc Natl Acad Sci USA 90: 1132–1136
Thurnauer MC and Norris JR (1980) An electron spin echo phase shift observed in photosynthetic algae. Possible evidence for dynamic radical pair interactions. Chem Phys Lett 76: 557–561
van der Est A, Bock C, Golbeck, J Brettel K, Setif P and Stehlik D (1994) Electron transfer from the acceptor A1 to the iron sulfur centers in Photosystem I as studied by transient EPR spectroscopy. Biochemistry 33: 11789–11797
Warren PV, Smart LB, McIntosh L and Golbeck JH (1992) Site-directed conversion of cysteine-565 to serine in psaB of Photosystem-1 results in the assembly of [3Fe-4S] and [4Fe-4S] clusters in F(x) – a mixed-ligand [4Fe-4S] cluster is capable of electron transfer to F(a) and F(b). Biochemistry 32: 4411–4419
Warren PV, Golbeck JH and Warden JT (1993) Charge recombination between P700+ and A1 - occurs directly to the ground state of P700 in a Photosystem 1 core devoid of Fx, Fb, and Fa. Biochemistry 32: 849–857
Webber AN and Bingham SE (1998) Structure and function of Photosystem I. In: Rochaix J-D, Goldschmidt-Clermont M and Merchant S (eds) The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas, pp 323–348. Kluwer Academic Publishers, Dordrecht, The Netherlands
Webber AN, Gibbs PB, Ward JB and Bingham SE (1993) Sitedirected mutagenesis of the Photosystem-I reaction center in chloroplasts – the proline-cysteine motif. J Biol Chem 268 12990–12995
Wynn RM and Malkin R (1988) Characterisation of an isolated chloroplast membrane Fe-S protein and its identification as the Photosystem I Fe-SA/Fe-SB binding protein. FEBS Lett 229: 293–297
Yu L, Zhao JD, Muhlenhoff U, Bryant DA and Golbeck JH (1993) PsaE is required for in vivo cyclic electron flow around Photosystem I in the cyanobacterium Synechococcus sp. Pcc-7002. Plant Physiol 103: 171–180
Zeng M, Sagi I, Evans MCW, Nelson N and Carmeli C (1999) Site directed and suppressor mutants of Fx ligands in PsaB of Photosystem I in Synechocystis sp. Pcc 6803. In: Garab G (ed) Photosynthesis: Mechanisms and Effects, Vol I, pp 643–646. Kluwer Academic Publishers, Dordrecht, The Netherlands
Zhao J, Warren PV, Li N, Bryant DA and Golbeck JH (1990) Reconstitution of electron transport in Photosystem I with PsaC and PsaD proteins expressed in Escherichia coli. FEBS Lett 276: 175–180
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Evans, M.C., Purton, S., Patel, V. et al. Modification of electron transfer from the quinone electron carrier, A1, of Photosystem 1 in a site directed mutant D576→L within the Fe-Sx binding site of PsaA and in second site suppressors of the mutation in Chlamydomonas reinhardtii. Photosynthesis Research 61, 33–42 (1999). https://doi.org/10.1023/A:1006205811407
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DOI: https://doi.org/10.1023/A:1006205811407