Abstract
Four distinct integration/translocation routes into/across thylakoid membranes have recently been deduced for nuclear-encoded polypeptides of the photosynthetic membrane. Corresponding information for the plastid-encoded protein complement is lacking. We have investigated this aspect with in-organello assays employing chimeric constructs generated with codoncorrect cassettes for genes of plastid-encoded thylakoid proteins, and appropriate transit peptides from six nuclear genes, representing three targeting classes, as a strategy. The three major plastid-encoded components of the cytochrome b 6f complex, namely pre-apocytochrome f, (including apocytochrome f, and pre-apocytochrome f lacking the C-terminal transmembrane segment), cytochrome b6, and subunit IV, which differ in the number of their transmembrane segments, were studied. Import into chloroplasts could be observed in all instances but with relatively low efficiency. Thylakoid integration can occurr post-translationally, but only components with secretory/secretory pathway (SEC)-route-specific epitopes were correctly assembled with the cytochrome complex, or competed with this process. Inhibitor studies were consistent with these findings. Imported cytochrome b6 and subunit IV operated with uncleaved targeting signals for thylakoid integration. The corresponding determinant for cytochrome f is its signal peptide; its C-terminal hydrophobic segment did not, or did not appreciably, contribute to this process. The N-termini of cytochrome b6 and subunit IV appear to reside on the same (lumenal) side of the membrane, consistent with the currently favored four-helix model for the cytochrome, but in disagreement with the topography proposed for both components. The impact of the findings for protein routing, including for applied approaches such as compartment-alien transformation, is discussed.
Similar content being viewed by others
Abbreviations
- FNR:
-
ferredoxin-NADP oxidoreductase
- PC:
-
plastocyanin
- PetA-D:
-
subunits of thylakoid-located cytochrome assembly
- PSI-2:
-
subunit II of PSI
- SEC:
-
secretory/secretory pathway
- SSU:
-
small subunit of Rubisco
References
Alt J, Herrmann RG (1984) Nucleotide sequence of the gene for preapocytochrome f in the spinach plastid chromosome. Curr Genet 8: 551–557
Alt J, Westhoff P, Sears BB, Nelson N, Hurt E, Hauska G, Herrmann RG (1983) Genes and transcripts for the polypeptides of the cytochrome b6/f complex from spinach thylakoid membranes. EMBO J 2: 979–986
Arnon DL (1949) Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris. Plant Physiol 24: 1–15
Bartlett SG, Grossman AR, Chua N-H (1982) In vitro synthesis and uptake of cytoplasmically synthesized chloroplast proteins. In: Edelmann M, Hallick RB, Chua N-H (eds) Methods in chloroplast molecular biology. Elsevier Biochemical Press, Amsterdam, pp 1081–1091
Bartling D, Clausmeyer S, Oelmüller R, Herrmann RG (1990) Towards epitope models for chloroplast transit sequences. Bot Mag (Tokyo) special issue 2: 119–144
Berghöfer J, Karnauchov I, Herrmann RG, Klösgen RB (1995) Isolation and characterization of a cDNA encoding the SecA protein from spinach chloroplasts: evidence for azide-resistance of Sec-dependent protein translocation across thylakoid membranes in spinach. J Biol Chem 270: 18341–18346
Cai D, Herrmann RG, Klösgen RB (1993) The 20 kDa apoproein of the CP24 complex of photosystem II: an alternative model to study import and intra-organellar routing of nuclear-encoded thylakoid proteins. Plant J 3: 383–392
Chamberlain JP (1979) Fluorographic detection of radioactivity in polyacrylamide gels with the water-soluble fluor sodium salicylate. Anal Biochem 98: 132–135
Cheung Y, Bogorad L, Van Montagu M, Schell J (1988) Relocating a gene for herbicide tolerance: a chloroplast gene is converted into a nuclear gene. Proc Natl Acad Sci USA 85: 391–395
Clausmeyer S, Klösgen RB, Herrmann RG (1993) Protein import into chloroplasts: the hydrophilic lumenal proteins exhibit unexpected import and sorting specificies in spite of structurally conserved transit peptides. J Biol Chem 268: 13869–13876
Cline K, Henry R, Li C, Yuan J (1993) Multiple pathways for protein transport into or across the thylakoid membrane. EMBO J 12: 4105–4114
Cramer WA, Black MT, Widger WR, Girvin ME (1987) Structure and function of photosynthetic bc1 and b6f complexes. In: Barber J (ed) The light reactions. Elsevier Sci Publ BV, Amsterdam, The Netherlands, pp 447–493
de Vitry C, Breyton C, Pierre Y, Popot J-L (1996) The 4-kDa nuclear-encoded petM polypeptide of the chloroplast cytochrome b 6 f complex. J Biol Chem 271: 10667–10671
Driessen AJM, Wit JG de, Kuiper W, Wolk JPW van der, Fekkes P, Does C van der, Wely K van, Manting E, Blaauwen T den (1995) SecA, a novel ATPase that converts chemical energy into a mechanical force to drive precursor protein translocation. Biochem Soc Trans 23: 981–985
Frank K, Trebst A (1995) Quinone binding sites on cytochrome b/c complexes. Photochem Photobiol 61: 2–9
Friemann A, Hachtel W (1988) Chloroplast messenger RNAs of free and thylakoid-bound polysomes from Vicia faba L. Planta 175: 50–59
Hauska G, Hurt E, Gabellini N, Lockau W (1983) Comparative aspects of quinol-cytochrome c/plastocyanin oxidoreductases. Biochim Biophys Acta 726: 97–113
Hauska G, Nitschke W, Herrmann RG (1988) Amino acid identities in the three redox center carrying polypeptides of cytochrome bc1/b6f-complexes. J Bioenerg Biomembr 20: 211–228
Heinemeyer W, Alt J, Herrmann RG (1984) Nucleotide sequence of the genes for apocytochrome b6 and subunit 4 of the cytochrome b/f complex in the spinach plastid chromosome. Curr Genet 8: 543–449
Herrmann RG (1996) Photosynthesis research —aspects and perspectives. In: Andersson B, Salter AH, Barber J (eds) Frontiers in molecular biology. Molecular genetics in photosynthesis. Oxford University Press, pp 1–44
Johnson EM, Schnabelrauch LS, Sears BB (1991) A plastome mutation affects processing of both chloroplast and nuclear DNA-encoded plastid proteins. Mol Gen Genet 225: 106–112
Kanevski I, Maliga P (1994) Relocation of the plastid rbcL gene to the nucleus yields functional ribulose-1,5-bisphosphate carboxylase in tobacco chloroplasts. Proc Natl Acad Sci USA 91: 1969–1973
Karnauchov I, Cai D, Schmidt I, Herrmann RG, Klösgen RB (1994) The thylakoid translocation of the nuclear-encoded subunit 3 of photosystem I depends on a bipartite transit peptide and proceeds along an azide-sensitive pathway. J Biol Chem 269: 32871–32878
Karnauchov I, Herrmann RG, Pakrasi HB, Klösgen RB (1996) The CtpA protein from the cyanobacterium Synchocystis 6803 can utilize two pathways for its transport across the thylakoid membrane in chloroplasts. Biol Chem, in press
Kirwin PM, Elderfield PD, Robinson C (1987) Transport of proteins into chloroplasts: partial purification of a thylakoid processing peptidase involved in plastocyanin biogenesis. J Biol Chem 262: 16386–16390
Kuras R, Wollman F-A, Joliot P (1995a) Conversion of cytochrome f to a soluble form in vivo in Chlamydomonas reinhardtii. Biochemistry 34: 7468–7475
Kuras R, Büschlen S, Wollman F-A (1995b) Maturation of preapocytochrome f in vivo. A site-directed mutagenesis study in Chlamydomonas reinhardtii. J Biol Chem 270: 27797–27803
Laemmli UK (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227: 680–685
Li X, Henry R, Yuan J, Cline K, Hoffman N (1995) A chloroplast homolog of the signal recognition particle subunit SRP54 is involved in the posttranslational integration of a protein into thylakoid membranes. Proc Natl Acad Sci USA 92: 3789–3793
Martinez SE, Huang D, Szczepaniak A, Cramer WA, Smith JL (1994) Crystal structure of chloroplast cytochrome f reveals a novel cytochrome fold and unexpected heme ligation. Structure 2: 95–105
Michl D, Robinson C, Shackleton JB, Herrmann RG, Klösgen RB (1994) Targeting of proteins to the thylakoids by bipartite presequences: CFo-II is imported by a novel, third pathway. EMBO J 13: 1310–1317
Nagley P, Devenish RJ (1989) Leading organellar proteins along new pathways: the relocation of mitochondrial and chloroplast genes to the nucleus. TIBS 14: 31–35
Nakai M, Goto A, Nohara T, Sugita D, Endo T (1994) Identification of the SecA protein homolog in pea chloroplasts and its possible involvement in thylakoidal protein transport. J Biol Chem 266: 31338–31341
Olesch B (1983) Analyse plastidärer und nukleärer Mutanten von Oenothera. Staatsexamensarbeit, Universität Düsseldorf, Germany
Robinson C, Klösgen RB (1994) Targeting of proteins into and across the thylakoid membrane —a multitude of mechanisms. Plant Mol Biol 26: 15–24
Robinson C, Cai D, Hulford A, Brock IW, Michl D, Hazell L, Schmidt I, Herrmann RG, Klösgen RB (1994) The presequence of a chimeric construct dictates which of two mechanisms are utilized for translocation across the thylakoid membrane: evidence for the existence of two distinct translocation systems. EMBO J 13: 279–285
Rothstein SJ, Gatenby AA, Willey DL, Gray JC (1985) Binding of pea cytochrome f to the inner membrane of Escherichia coli requires the bacterial secA gene product. Proc Natl Acad Sci USA 82: 7955–7959
Schoepfer R (1993) pRSET family of T7 promoter expression vectors for Escherichia coli. Gene 124: 83–85
Shinozaki K, Ohme M, Tanaka M, Wakasugi T, Hayashida N, Matsubayashi T, Zaita N, Chungwongse J, Obokata J, Yamaguchi-Shinozaki K, Ohto C, Torazawa K, Meng BY, Sugita M, Deno H, Kamogashira T, Yamada K, Kusuda J, Takaiwa F, Kato A, Tohdo N, Shimada H, Sugiura M (1986) The complete nucleotide sequence of the tobacco chloroplast genome: its gene organization and expression. EMBO J 5: 2043–2049
Smith TA, Kohorn BD (1994) Mutations in a signal sequence for the thylakoid membrane identify multiple protein transport pathways and nuclear suppressors. J Cell Biol 126: 365–374
Steppuhn J, Rother C, Hermans J, Jansen T, Salnikow J, Hauska G, Herrmann RG (1987) The complete amino acid sequence of the Rieske FeS-precursor protein from spinach chloroplasts deduced from cDNA analysis. Mol Gen Genet 210: 171–177
Szczepaniak A, Black MT, Cramer WA (1989) Topography of the chloroplast cytochrome b6: orientation of the cytochrome and accessibility of the lumen-side interhelix loops. Z Naturforsch 44C: 453–461
Tittgen J, Hermans J, Steppuhn J, Jansen T, Jansson C, Andersson B, Nechushtai R, Nelson N, Herrmann RG (1986) Isolation of cDNA clones for fourteen nuclear-encoded thylakoid membrane proteins. Mol Gen Genet 204: 258–265
Tyagi AK, Herrmann RG (1986) Location and nucleotide sequence of the pre-apocytochrome f gene on the Oenothera hookeri plastid chromosome (Euoenothera plastome I). Curr Genet 10: 481–486
Widger WR, Cramer WA, Herrmann RG, Trebst A (1984) Sequence homology and structural similarity between b cytochromes from five different mitochondrial sources and two subunits of the chloroplast b6-f complex: model for the arrangement of the cytochrome b polypeptide and hemes in the membrane. Proc Natl Acad Sci USA 81: 674–678
Willey DL, Auffret AD, Gray JC (1984) Structure and topology of cytochrome f in pea chloroplast membranes. Cell 36: 555–562
Yuan J, Henry R, McCaffery M, Cline K (1994) SecA homolog in protein transport within chloroplasts: evidence for endosymbiont-derived sorting. Science 266: 796–798
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Zak, E., Sokolenko, A., Unterholzner, G. et al. On the mode of integration of plastid-encoded components of the cytochrome bf complex into thylakoid membranes. Planta 201, 334–341 (1997). https://doi.org/10.1007/s004250050075
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s004250050075