Effect of mutations on the binding and translocation functions of a chloroplast transit peptide.
- 1 February 1989
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 86 (3) , 886-890
- https://doi.org/10.1073/pnas.86.3.886
Abstract
We studied transport and binding to intact chloroplasts of 10 mutants in three regions of the transit peptide of a precursor to the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase [3-phospho-D-glycerate carboxy-lyase (transphosphorylating), E.C.4.1.1.39]. Transport was assayed in a reconstituted system using isolated pea chloroplasts and radioactively labeled precursor. Binding to the chloroplast envelope was assayed in a similar manner using chloroplasts pretreated with nigericin. Most mutants showed a dramatically decreased capacity of binding, although some of them transported relatively well. The accumulation of the mutant proteins inside the chloroplast as a function of time was examined. Although the authentic small subunit precursor was imported rapidly, uptake of most mutant precursors was considerably slower and continued until the last time point examined. In terms of assigning functions to individual regions, we found that at least the middle region and parts of the amino and the carboxyl termini of the transit peptide are more important for receptor binding than for translocation. A two-step processing mechanism has been postulated for the maturation of the small subunit precursor. This model predicts the occurrence of processing intermediates. When precursors carrying carbaxylterminal deletions were presented to the chloroplast, no defined intermediates could be detected. Instead, a number of proteins, probably resulting from aberrant processing, accumulated simultaneously inside the chloroplasts.This publication has 27 references indexed in Scilit:
- Identification of a receptor for protein import into chloroplasts and its localization to envelope contact zonesNature, 1988
- Evidence that a Chloroplast Surface Protein Is Associated with a Specific Binding Site for the Precursor to the Small Subunit of Ribulose-1,5-Bisphosphate CarboxylasePlant Physiology, 1987
- The role of the transit peptide in the routing of precursors toward different chloroplast compartmentsCell, 1986
- THE TRANSPORT OF PROTEINS INTO CHLOROPLASTSAnnual Review of Biochemistry, 1986
- Targeting of a foreign protein to chloroplasts by fusion to the transit peptide from the small subunit of ribulose 1,5-bisphosphate carboxylaseNature, 1985
- Functional determinants in transit sequences: import and partial maturation by vascular plant chloroplasts of the ribulose-1,5-bisphosphate carboxylase small subunit of Chlamydomonas.The Journal of cell biology, 1985
- Transport of proteins into chloroplastsEuropean Journal of Biochemistry, 1984
- Transport of proteins into mitochondria and chloroplasts.The Journal of cell biology, 1979
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970
- COPPER ENZYMES IN ISOLATED CHLOROPLASTS. POLYPHENOLOXIDASE IN BETA VULGARISPlant Physiology, 1949