Conditional Barley Mutant Chlorina-104 Lacks A HSP70 Homologue of the Chloroplast Protein Import Complex Under Restrictive Growth Conditions

  • Jürgen Knoetzel
  • L. Horst Grimme


Four proteins constitute the translocon complex of the outer envelope membrane of chloroplasts. Toc34, Toc86 and Toc75 mediate the initial binding of preproteins and subsequent translocation across the outer envelope in an ATP/GTP-dependent manner (1, 2, 3, 4). Subsequently, a translocon complex transports the preproteins across the inner envelope membrane driven by ATP hydrolysis in the stroma (5, 6). Both complexes associate at contact sites between the outer and inner envelope to facilitate direct translocation from the cytoplasma to the stroma. Molecular chaperones associated with or embedded in the outer envelope, Com70 and Hsc70, respectively, and at the stromal side of the inner envelope, C1pC and Cpn60, participate in driving the transport and may serve to induce or stabilize unfolded import-competent conformation of the preprotein, and/or folding of proteins in the stroma after import (7, 8, 9, 10).

Key words

Chaperone proteins mutants (barley) protein import reconstitution 


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  1. 1.
    Schnell, D.J. (1995) Cell 83, 521–524.CrossRefPubMedGoogle Scholar
  2. 2.
    Soll, J. (1995) Bot. Acta 108, 277–282.CrossRefGoogle Scholar
  3. 3.
    Scott, S.V. and Theg, S.M. (1996) J. Cell Biol. 132, 63–75.CrossRefPubMedGoogle Scholar
  4. 4.
    Kouranov, A. and Schnell, D. (1997) J. Cell Biol. 139, 1677–1685.CrossRefPubMedPubMedCentralGoogle Scholar
  5. 5.
    Theg, S.M., BAuerle C., Olsen L.J., Selman B.R. and Keegstra K. (1989) J. Biol. Chem. 264, 6730–6736.PubMedGoogle Scholar
  6. 6.
    Theg, S.M. and Scott, S.V. (1993) Trends Cell Biol. 3, 186–190.CrossRefPubMedGoogle Scholar
  7. 7.
    Marshall, J.S., DeRocher, A.E., Keegstra, K. and Vierling, J.E. (1990) Proc. Natl. Acad. Sei. USA 87, 374–378.CrossRefGoogle Scholar
  8. 8.
    Ko, K., Bomemisza, O., Kourtz, L., Ko, ZW., Plaxton, W.C. and Cashmore, A.R. (1992) J. Biol. Chem. 267, 2986–2993.PubMedGoogle Scholar
  9. 9.
    Kessler, F. and Blobel, G. (1996) Proc. Natl. Acad. Sei. USA 93, 7684–7689.CrossRefGoogle Scholar
  10. 10.
    Nielsen, E., Akita, M., Davila-Aponte, J. and Keegstra, K. (1997) EMBO J. 16, 935–946.CrossRefPubMedPubMedCentralGoogle Scholar
  11. 11.
    Knoetzel, J. and Simpson, D.J. (1991) Planta 185, 111–123.CrossRefPubMedGoogle Scholar
  12. 12.
    Meyer, D.U., Knoetzel, J. and Grimme, L.H. (1995) in Photosynthesis: from Light to Biosphere (Mathis, P., ed.), pp. 775–778, Kluwer Academic Publishers, Dordrecht, The Netherlands.Google Scholar
  13. 13.
    Nielsen, V.S., Mont, A., Knoetzel, J., Møller, B.L. and Robinson, C. (1994) J. Biol. Chem. 269, 3762–3766.PubMedGoogle Scholar
  14. 14.
    Bossznann, B., Knoetzel, J. and Jansson, S. (1997) Photosynth. Res. 52, 127–136.CrossRefGoogle Scholar
  15. 15.
    Schnell, D.J., Kessler, F. and Blobel, G. (1994) Science 266, 1007–1012.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1998

Authors and Affiliations

  • Jürgen Knoetzel
    • 1
  • L. Horst Grimme
    • 1
  1. 1.Institute of Cell Biology, Biochemistry and BiotechnologyUniversity of BremenBremenGermany

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