Comparison of the electron transport properties of the psbo1 and psbo2 mutants of Arabidopsis thaliana

Abstract

Genome sequence of Arabidopsis thaliana (Arabidopsis) revealed two psbO genes (At5g66570 and At3g50820) which encode two distinct PsbO isoforms: PsbO1 and PsbO2, respectively. To get insights into the function of the PsbO1 and PsbO2 isoforms in Arabidopsis we have performed systematic and comprehensive investigations of the whole photosynthetic electron transfer chain in the T-DNA insertion mutant lines, psbo1 and psbo2. The absence of the PsbO1 isoform and presence of only the PsbO2 isoform in the psbo1 mutant results in (i) malfunction of both the donor and acceptor sides of Photosystem (PS) II and (ii) high sensitivity of PSII centers to photodamage, thus implying the importance of the PsbO1 isoform for proper structure and function of PSII. The presence of only the PsbO2 isoform in the PSII centers has consequences not only to the function of PSII but also to the PSI/PSII ratio in thylakoids. These results in modification of the whole electron transfer chain with higher rate of cyclic electron transfer around PSI, faster induction of NPQ and a larger size of the PQ-pool compared to WT, being in line with apparently increased chlororespiration in the psbo1 mutant plants. The presence of only the PsbO1 isoform in the psbo2 mutant did not induce any significant differences in the performance of PSII under standard growth conditions as compared to WT. Nevertheless, under high light illumination, it seems that the presence of also the PsbO2 isoform becomes favourable for efficient repair of the PSII complex.

The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis

“…results are in good agreement with the reduced NPQ observed in pam71 compared with the wild type under steady state illumination conditions (Table 1), as the major component of NPQ, energy-dependent quenching, is strictly dependent on an acidic lumenal pH (Ruban et al, 2012;Zaks et al, 2013). Accordingly, the increase in NPQ in pam71 leaves exposed to short illumination periods (Supplemental Table 1) is similar to observations made with a psbo1 mutant (Allahverdiyeva et al, 2009). In pam71, a reduced linear electron flow is evident from the reduced effective quantum yield of PSII ( Figures 3A and 3D).…”

“…There are two distinct isoforms in Arabidopsis, PsbO1 and PsbO2, with the PsbO1 isoform being by far the more abundant of the two (Murakami et al, 2002). The psbo1 mutant exhibits a distinctive phenotype, with pale-green leaves, reduced rosette size, and slower growth rate, which underlines the importance of the PsbO1 isoform for the structure and function of PSII (Murakami et al, 2002;Lundin et al, 2007;Bricker and Frankel, 2008;Allahverdiyeva et al, 2009).…”

Reorganization of photosystem II is involved in the rapid photosynthetic recovery of desert moss Syntrichia caninervis upon rehydration

“…1B). The activity of PQ reduction is regulated not only by the activity of PSII, but also by the activation of Cyt b 6 f and PSI (El Bissati and Kirilovsky, 2001;Schwenkert et al, 2007;Hald et al, 2008;Allahverdiyeva et al, 2009). The amount of PQ-pool is a factor regulating the redox state of the thylakoid membrane.…”

Light-triggered selective nitration of PsbO1 in isolated Arabidopsis thylakoid membranes is inhibited by photosynthetic electron transport inhibitors

“…3,13 The same was true when intact leaves were exposed to NO 2 as reported previously. 1 In contrast, EPR studies of isolated Arabidopsis PSII membranes following treatment with tetranitromethane 23 or peroxynitrite 24 have shown distinct nitration of Y z and Y D 23 or small but distinct nitration of Y Z . 24 The reason(s) for this discrepancy between nitroproteome and EPR studies needs to be elucidated in future studies.…”