Abstract
The precursor to the light-harvesting chlorophyll a/b protein of photosystem II can insert into isolated thylakoid membranes if reaction mixtures also contain ATP and a soluble extract of chloroplasts. Optimization of this insertion process and the initial characterization of the soluble chloroplastic component are presented. With a fixed amount of precursor, maximum integration rates occurred during the first 30 minutes at pH 8.0 and 30°C when the soluble chloroplast extract was increased eight-fold over the stoichiometric amount. Under these conditions, insertion was routinely about 60% of that which occurred during import into intact chloroplasts. Integration also increased virtually linearly with increasing amounts of precursor. However, assays revealed that at least 40% of the in vitro-synthesized pLHCP was pelletable and inactive. The soluble chloroplastic component exhibited characteristics expected of a protein. It was inactivated by heat, protease, and N-ethylmaleimide, but was insensitive to ribonuclease. The soluble component migrated on a Sephacryl S-200 gel filtration column as a single peak with an Mr of approximately 65,000. The proteinaceous nature of this factor suggests a similarity to soluble factors required for protein transport/integration in other membrane systems.
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- Andersson B., Anderson J. M., Ryrie I. J. Transbilayer organization of the chlorophyll-proteins of spinach thylakoids. Eur J Biochem. 1982 Apr 1;123(2):465–472. doi: 10.1111/j.1432-1033.1982.tb19790.x. [DOI] [PubMed] [Google Scholar]
- Argan C., Shore G. C. The precursor to ornithine carbamyl transferase is transported to mitochondria as a 5S complex containing an import factor. Biochem Biophys Res Commun. 1985 Aug 30;131(1):289–298. doi: 10.1016/0006-291x(85)91801-7. [DOI] [PubMed] [Google Scholar]
- Burns D., Lewin A. Inhibition of the import of mitochondrial proteins by RNase. J Biol Chem. 1986 May 15;261(14):6153–6155. [PubMed] [Google Scholar]
- Cashmore A. R. Structure and expression of a pea nuclear gene encoding a chlorophyll a/b-binding polypeptide. Proc Natl Acad Sci U S A. 1984 May;81(10):2960–2964. doi: 10.1073/pnas.81.10.2960. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline K. Import of proteins into chloroplasts. Membrane integration of a thylakoid precursor protein reconstituted in chloroplast lysates. J Biol Chem. 1986 Nov 5;261(31):14804–14810. [PubMed] [Google Scholar]
- Cline K. Light-Harvesting Chlorophyll a/b Protein : Membrane Insertion, Proteolytic Processing, Assembly into LHC II, and Localization to Appressed Membranes Occurs in Chloroplast Lysates. Plant Physiol. 1988 Apr;86(4):1120–1126. doi: 10.1104/pp.86.4.1120. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline K., Werner-Washburne M., Andrews J., Keegstra K. Thermolysin is a suitable protease for probing the surface of intact pea chloroplasts. Plant Physiol. 1984 Jul;75(3):675–678. doi: 10.1104/pp.75.3.675. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline K., Werner-Washburne M., Lubben T. H., Keegstra K. Precursors to two nuclear-encoded chloroplast proteins bind to the outer envelope membrane before being imported into chloroplasts. J Biol Chem. 1985 Mar 25;260(6):3691–3696. [PubMed] [Google Scholar]
- Crooke E., Wickner W. Trigger factor: a soluble protein that folds pro-OmpA into a membrane-assembly-competent form. Proc Natl Acad Sci U S A. 1987 Aug;84(15):5216–5220. doi: 10.1073/pnas.84.15.5216. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ellis R. J. Chloroplast protein synthesis: principles and problems. Subcell Biochem. 1983;9:237–261. doi: 10.1007/978-1-4613-3533-7_2. [DOI] [PubMed] [Google Scholar]
- Hartl F. U., Ostermann J., Guiard B., Neupert W. Successive translocation into and out of the mitochondrial matrix: targeting of proteins to the intermembrane space by a bipartite signal peptide. Cell. 1987 Dec 24;51(6):1027–1037. doi: 10.1016/0092-8674(87)90589-7. [DOI] [PubMed] [Google Scholar]
- Hartl F. U., Schmidt B., Wachter E., Weiss H., Neupert W. Transport into mitochondria and intramitochondrial sorting of the Fe/S protein of ubiquinol-cytochrome c reductase. Cell. 1986 Dec 26;47(6):939–951. doi: 10.1016/0092-8674(86)90809-3. [DOI] [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Maher P. A., Singer S. J. Disulfide bonds and the translocation of proteins across membranes. Proc Natl Acad Sci U S A. 1986 Dec;83(23):9001–9005. doi: 10.1073/pnas.83.23.9001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mattoo A. K., Edelman M. Intramembrane translocation and posttranslational palmitoylation of the chloroplast 32-kDa herbicide-binding protein. Proc Natl Acad Sci U S A. 1987 Mar;84(6):1497–1501. doi: 10.1073/pnas.84.6.1497. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Müller M., Blobel G. Protein export in Escherichia coli requires a soluble activity. Proc Natl Acad Sci U S A. 1984 Dec;81(24):7737–7741. doi: 10.1073/pnas.81.24.7737. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rothman J. E., Kornberg R. D. Cell biology. An unfolding story of protein translocation. Nature. 1986 Jul 17;322(6076):209–210. doi: 10.1038/322209a0. [DOI] [PubMed] [Google Scholar]
- Schmidt G. W., Mishkind M. L. The transport of proteins into chloroplasts. Annu Rev Biochem. 1986;55:879–912. doi: 10.1146/annurev.bi.55.070186.004311. [DOI] [PubMed] [Google Scholar]
- Shih M. C., Lazar G., Goodman H. M. Evidence in favor of the symbiotic origin of chloroplasts: primary structure and evolution of tobacco glyceraldehyde-3-phosphate dehydrogenases. Cell. 1986 Oct 10;47(1):73–80. doi: 10.1016/0092-8674(86)90367-3. [DOI] [PubMed] [Google Scholar]
- Smeekens S., Bauerle C., Hageman J., Keegstra K., Weisbeek P. The role of the transit peptide in the routing of precursors toward different chloroplast compartments. Cell. 1986 Aug 1;46(3):365–375. doi: 10.1016/0092-8674(86)90657-4. [DOI] [PubMed] [Google Scholar]
- Walter P., Blobel G. Purification of a membrane-associated protein complex required for protein translocation across the endoplasmic reticulum. Proc Natl Acad Sci U S A. 1980 Dec;77(12):7112–7116. doi: 10.1073/pnas.77.12.7112. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walter P., Blobel G. Signal recognition particle contains a 7S RNA essential for protein translocation across the endoplasmic reticulum. Nature. 1982 Oct 21;299(5885):691–698. doi: 10.1038/299691a0. [DOI] [PubMed] [Google Scholar]
- Walter P., Blobel G. Subcellular distribution of signal recognition particle and 7SL-RNA determined with polypeptide-specific antibodies and complementary DNA probe. J Cell Biol. 1983 Dec;97(6):1693–1699. doi: 10.1083/jcb.97.6.1693. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walter P., Ibrahimi I., Blobel G. Translocation of proteins across the endoplasmic reticulum. I. Signal recognition protein (SRP) binds to in-vitro-assembled polysomes synthesizing secretory protein. J Cell Biol. 1981 Nov;91(2 Pt 1):545–550. doi: 10.1083/jcb.91.2.545. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Waters M. G., Chirico W. J., Blobel G. Protein translocation across the yeast microsomal membrane is stimulated by a soluble factor. J Cell Biol. 1986 Dec;103(6 Pt 2):2629–2636. doi: 10.1083/jcb.103.6.2629. [DOI] [PMC free article] [PubMed] [Google Scholar]