Synthesis of reaction center proteins and reactivation of redox components during repair of photosystem II after light-induced inactivation.

K J Van Wijk,L O Nilsson,S Styring

doi:10.1016/s0021-9258(18)46939-6

K J Van Wijk, L O Nilsson + Show 1 more

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https://doi.org/10.1016/s0021-9258(18)46939-6

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Journal: The Journal of biological chemistry	Publication Date: Nov 1, 1994
Citations: 41	License type: cc-by

Affiliation: Stockholm University

Abstract

The D1 reaction center protein in photosystem II (PSII) has a high turnover rate due to light-induced inactivation of the redox components. We have studied the reactivation kinetics of the redox components of PSII after strong illumination and compared these kinetics with the turnover of the D1 protein and translation kinetics of the plastid-encoded PSII core proteins in Chlamydomonas reinhardtii cells. Repair of PSII was to a large extent dependent on protein translation. During the first hours of repair, D1 translation was highly accelerated as compared to the other PSII core proteins. By addition of protein synthesis inhibitors during the recovery process, it was found that the time from protein synthesis to full reassembly and reactivation of the individual PSII complexes was about 55 +/- 10 min. Inactivation and reactivation of the redox components in PSII were followed by electron spin resonance and electron transport measurements. Combining the data shows that reactivation of the individual components proceeded together or shortly after one another. Thus, no accumulation of any partially active reactivation intermediate occurred. We conclude that the rate-limiting step of the repair cycle of PSII lies in the degradation and synthesis of the PSII reaction center proteins. Once stable synthesis of the PSII core proteins is achieved, reactivation of the redox components occurs very quickly.

Highlights

(PSII) has a high turnover rate due to light-induced i1n--4)
The inactivation of PSII is reversible without activationof the redox componentW s.e have studied theneed for replacement of cofactors or PSII proteins,’ but in later reactivation kinetics of the redox components of PSII after strong illumination and compared these kinetics withtheturnoverofthe D l proteinandtranslation kinetics of the plastid-encoded PSII core proteins in Chlamydomonasreinhardtii cells
No accumulation of any par- translation. This would provide a tight coupling between D l tially active reactivation intermediate occuWrreecdo.nclude that the rate-limiting step of the repair cycle of PSII lies in the degradation and synthesis of the PSII reaction center proteins

Summary

EXPERIMENTAL PROCEDURES

The reactivation of PSII after photoinhibition requires Cell Growth and Isolation of Thylakoids-Cell-wall less (CW15) C. Only to about 40%, which was reached in abo2uth (Fig. 1).PSII activity measured by chlorophyll fluorescence ( F J F , ) correlated in linear fashion with0,theevolution (not shown) both in the inhibition anredcovery phase, as demonstrated earlier[29] These resultsshow that full recovery was dependenton synthesis of one or several chloroplast-encoded proteins. The synthesis rate of CP47 was approximately equal to that of CP43 (Fig. 3A).Directly after transfer of the control cells fromthe low temperature (but idnarkness) to the recovery conditions, Dl synthesis was about twice as high as for the D2 protein and about four times higher as for CP43. Inthe first hour after transfer to after 6 h of recovery,when the PSII activity was recovery conditions,the D l loss was nearly identical to the loss measured in absence of the inhibitors (Fig. 2A)

Control Photoinhibited iOh

DISCUSSION

Findings

Reactivation of PSII afZer Photoinhibition