A Chloroplast-Targeted Heat Shock Protein 70 (HSP70) Contributes to the Photoprotection and Repair of Photosystem II during and after Photoinhibition
Open Access
- 1 June 1999
- journal article
- Published by Oxford University Press (OUP) in Plant Cell
- Vol. 11 (6), 1165-1178
- https://doi.org/10.1105/tpc.11.6.1165
Abstract
Dark-grown Chlamydomonas reinhardtii cultures that were illuminated at low fluence rates before exposure to highlight conditions exhibited a faster rate of recovery from photoinhibition than did dark-grown cells that were directly exposed to photoinhibitory conditions. This pretreatment has been shown to induce the expression of several nuclear heat shock protein 70 (HSP70) genes, including HSP70B, encoding a chloroplast-localized chaperone. To investigate a possible role of plastidic HSP70B in photoprotection and repair of photosystem II, which is the major target of photoinhibition, we have constructed strains overexpressing or underexpressing HSP70B. The effect of light stress on photosystem II in nuclear transformants harboring HSP70B in the sense or antisense orientation was monitored by measuring variable fluorescence, flash-induced charge separation, and relative amounts of various photosystem II polypeptides. Underexpression of HSP70B caused an increased light sensitivity of photosystem II, whereas overexpression of HSP70B had a protective effect. Furthermore, the reactivation of photosystem II after photoinhibition was enhanced in the HSP70B-overexpressing strain when compared with the wild type, both in the presence or absence of synthesis of chloroplast-encoded proteins. Therefore, HSP70B may participate in vivo both in the molecular protection of the photosystem II reaction centers during photoinhibition and in the process of photosystem II repair.Keywords
This publication has 45 references indexed in Scilit:
- Chlorophyll precursors are signals of chloroplast origin involved in light induction of nuclear heat-shock genesProceedings of the National Academy of Sciences of the United States of America, 1997
- Cloning and characterization of LRG5 , a gene involved in blue light signaling in Chlamydomonas gametogenesisThe Plant Journal, 1997
- Heat shock and light activation of aChlamydomonas HSP70 gene are mediated by independent regulatory pathwaysMolecular Genetics and Genomics, 1995
- Regulation of Light Harvesting in Green Plants (Indication by Nonphotochemical Quenching of Chlorophyll Fluorescence)Plant Physiology, 1994
- Role of plastoquinol oxidoreduction in regulation of photochemical reaction center IID1 protein turnover in vivoJournal of Biological Chemistry, 1994
- Photosystem II Reaction Center Damage and Repair in Dunaliella salina (Green Alga) (Analysis under Physiological and Irradiance-Stress Conditions)Plant Physiology, 1993
- Isolation and characterization of a cDNA clone encoding a cognate 70-kDa heat shock protein of the chloroplast envelope.Journal of Biological Chemistry, 1992
- Light-dependent D1 protein synthesis and translocation is regulated by reaction center II. Reaction center II serves as an acceptor for the D1 precursor.Journal of Biological Chemistry, 1990
- Posttranslational events leading to the assembly of photosystem II protein complex: a study using photosynthesis mutants from Chlamydomonas reinhardtii.The Journal of cell biology, 1989
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970