A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
REGULATION OF D1 PROTEIN-DEGRADATION DURING PHOTOINHIBITION OF PHOTOSYSTEM-II IN-VIVO - PHOSPHORYLATION OF THE D1 PROTEIN IN VARIOUS PLANT GROUPS
Tekijät: RINTAMAKI E, SALO R, LEHTONEN E, ARO EM
Kustantaja: SPRINGER VERLAG
Julkaisuvuosi: 1995
Journal: Planta
Tietokannassa oleva lehden nimi: PLANTA
Lehden akronyymi: PLANTA
Vuosikerta: 195
Numero: 3
Aloitussivu: 379
Lopetussivu: 386
Sivujen määrä: 8
ISSN: 0032-0935
Tiivistelmä
Photoinhibition of PSII and turnover of the D1 reaction-centre protein in vivo were studied in pumpkin leaves (Cucurbita pepo L.) acclimated to different growth irradiances and in low-light-grown moss, Ceratodon purpureus (Hedw.) Brid. The low-light-acclimated pumpkins were most susceptible to photoinhibition. The production rate of photoinhibited PSII centres (k(PI)), determined in the presence of a chloroplast-encoded protein-synthesis inhibitor, showed no marked difference between the high- and low-light-grown pumpkin leaves. On the other hand, the rate constant for the repair cycle (k(REC)) of PSII was nearly three times higher in the high-light-grown pumpkin when compared to low-light-grown pumpkin. The slower degradation rate of the damaged D1 protein in the low-light-acclimated leaves, determined by pulse-chase experiments with [S-35]methionine suggested that the degradation of the D1 protein retards the repair cycle of PSII under photoinhibitory light. Slow degradation of the D1 protein in low-light-grown pumpkin was accompanied by accumulation of a phosphorylated form of the D1 protein, which we postulate as being involved in the regulation of D1-protein degradation and therefore the whole PSII repair cycle. In spite of low growth irradiance the repair cycle of PSII in the moss Ceratodon was rapid under high irradiance. When compared to the high- or low-light-acclimated pumpkin leaves, Ceratodon had the highest rate of D1-protein degradation at 1000 mu mol photons m(-2) s(-1). In contrast to the higher plants, the D1 protein of Ceratodon was not phosphorylated either under high irradiance in vivo or under in-vitro conditions, which readily phosphorylate the D1 protein of higher plants. This is consistent with the rapid degradation of the D1 protein in Ceratodon. Screening experiments indicated that D1 protein can be phosphorylated in the thylakoid membranes of angiosperms and conifers but not in lower plants. The postulated regulation mechanism of D1-protein degradation involving phosphorylation and the role of thylakoid organization in the function of PSII repair cycle are discussed.
Photoinhibition of PSII and turnover of the D1 reaction-centre protein in vivo were studied in pumpkin leaves (Cucurbita pepo L.) acclimated to different growth irradiances and in low-light-grown moss, Ceratodon purpureus (Hedw.) Brid. The low-light-acclimated pumpkins were most susceptible to photoinhibition. The production rate of photoinhibited PSII centres (k(PI)), determined in the presence of a chloroplast-encoded protein-synthesis inhibitor, showed no marked difference between the high- and low-light-grown pumpkin leaves. On the other hand, the rate constant for the repair cycle (k(REC)) of PSII was nearly three times higher in the high-light-grown pumpkin when compared to low-light-grown pumpkin. The slower degradation rate of the damaged D1 protein in the low-light-acclimated leaves, determined by pulse-chase experiments with [S-35]methionine suggested that the degradation of the D1 protein retards the repair cycle of PSII under photoinhibitory light. Slow degradation of the D1 protein in low-light-grown pumpkin was accompanied by accumulation of a phosphorylated form of the D1 protein, which we postulate as being involved in the regulation of D1-protein degradation and therefore the whole PSII repair cycle. In spite of low growth irradiance the repair cycle of PSII in the moss Ceratodon was rapid under high irradiance. When compared to the high- or low-light-acclimated pumpkin leaves, Ceratodon had the highest rate of D1-protein degradation at 1000 mu mol photons m(-2) s(-1). In contrast to the higher plants, the D1 protein of Ceratodon was not phosphorylated either under high irradiance in vivo or under in-vitro conditions, which readily phosphorylate the D1 protein of higher plants. This is consistent with the rapid degradation of the D1 protein in Ceratodon. Screening experiments indicated that D1 protein can be phosphorylated in the thylakoid membranes of angiosperms and conifers but not in lower plants. The postulated regulation mechanism of D1-protein degradation involving phosphorylation and the role of thylakoid organization in the function of PSII repair cycle are discussed.
Turun yliopiston Tutkimustietojärjestelmän portaali