A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in
            <i>Arabidopsis thaliana</i>

Fu, Aigen; He, Zengyong; Cho, Hye Sun; Lima, Amparo; Buchanan, Bob B.; Luan, Sheng

doi:10.1073/pnas.0707851104

Cited by 154 publications

(159 citation statements)

References 40 publications

Supporting

Mentioning

146

Contrasting

Unclassified

Order By: Relevance

“…Our earlier work suggests that FKBP20-2 and CYP38 chaperones function in the assembly of PSII SCs (14,15). Specifically, these proteins appear to be localized to the chloroplast thylakoid lumen where a major portion of the PSII complex resides.…”

Section: Resultsmentioning

confidence: 99%

PSB27: A thylakoid protein enabling Arabidopsis to adapt to changing light intensity

Hou

Garcia

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

In earlier studies we have identified FKBP20-2 and CYP38 as soluble proteins of the chloroplast thylakoid lumen that are required for the formation of photosystem II supercomplexes (PSII SCs). Subsequent work has identified another potential candidate functional in SC formation (PSB27). We have followed up on this possibility and isolated mutants defective in the PSB27 gene. In addition to lack of PSII SCs, mutant plants were severely stunted when cultivated with light of variable intensity. The stunted growth was associated with lower PSII efficiency and defective starch accumulation. In response to high light exposure, the mutant plants also displayed enhanced ROS production, leading to decreased biosynthesis of anthocyanin. Unexpectedly, we detected a second defect in the mutant, namely in CP26, an antenna protein known to be required for the formation of PSII SCs that has been linked to state transitions. Lack of PSII SCs was found to be independent of PSB27, but was due to a mutation in the previously described cp26 gene that we found had no effect on light adaptation. The present results suggest that PSII SCs, despite being required for state transitions, are not associated with acclimation to changing light intensity. Our results are consistent with the conclusion that PSB27 plays an essential role in enabling plants to adapt to fluctuating light intensity through a mechanism distinct from photosystem II supercomplexes and state transitions.photosystem | PSII supercomplex | photosynthesis | anthocyanin biosynthesis | reactive oxygen species P hotosynthetic light reactions entail the coordinated function of several large membrane complexes: photosystem I (PSI), photosystem II (PSII), cytochrome b6f complex, and CF 0 -CF 1 complex. PSII catalyzes the initial step of photosynthesis, the light-dependent oxidation of water that yields molecular oxygen and reduced plastoquinone. The native form of PSII residing in the thylakoid membrane is believed to be organized into several types of supercomplexes (SCs), including the PSII core and the peripheral light harvesting complex II (LHCII), that play a primary role in the harvesting of light, transfer of excitation energy to the reaction center and regulation of light utilization. Several monomeric antenna proteins including CP24, CP26, and CP29 regulate the interaction of the PSII core with LHCII trimers (1-4). Regulation is achieved through photoprotective mechanisms that dissipate absorbed excess energy as heat in response to stress conditions such as high light intensity (5, 6).In natural settings, both the intensity and the spectral quality of light vary extensively, sometimes within very short periods. The changes in light intensity result in imbalanced excitation of PSI and PSII, and with that may lower the efficiency of the photosynthetic light reactions. In acclimating to the changing conditions, plants modify their thylakoid proteins and reorganize their photosynthetic machinery (7,8). In a rapid response, designated state transitions (9), LHCII associates...

show abstract

Section: Resultsmentioning

confidence: 99%

PSB27: A thylakoid protein enabling Arabidopsis to adapt to changing light intensity

Hou

Garcia

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Measurement of chlorophyll fluorescence parameters and immunoblot analysis of thylakoid membrane proteins was conducted as described previously (31). BN SDS/PAGE analysis, oxygen evolution measurements, and production of recombinant AtCtpA protein were done as described elsewhere (32).…”

Section: Methodsmentioning

confidence: 99%

C-terminal processing of reaction center protein D1 is essential for the function and assembly of photosystem II inArabidopsis

Che

Hou³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

Photosystem II (PSII) reaction center protein D1 is synthesized as a precursor (pD1) with a short C-terminal extension. The pD1 is processed to mature D1 by carboxyl-terminal peptidase A to remove the C-terminal extension and form active protein. Here we report functional characterization of the Arabidopsis gene encoding D1 C-terminal processing enzyme (AtCtpA) in the chloroplast thylakoid lumen. Recombinant AtCtpA converted pD1 to mature D1 and a mutant lacking AtCtpA retained all D1 in precursor form, confirming that AtCtpA is solely responsible for processing. As with cyanobacterial ctpa, a knockout Arabidopsis atctpa mutant was lethal under normal growth conditions but was viable with sucrose under low-light conditions. Viable plants, however, showed deficiencies in PSII and thylakoid stacking. Surprisingly, unlike its cyanobacterial counterpart, the Arabidopsis mutant retained both monomer and dimer forms of the PSII complexes that, although nonfunctional, contained both the core and extrinsic subunits. This mutant was also essentially devoid of PSII supercomplexes, providing an unexpected link between D1 maturation and supercomplex assembly. A knock-down mutant expressing about 2% wild-type level of AtCtpA showed normal growth under low light but was stunted and accumulated pD1 under high light, indicative of delayed C-terminal processing. Although demonstrating the functional significance of C-terminal D1 processing in PSII biogenesis, our study reveals an unsuspected link between D1 maturation and PSII supercomplex assembly in land plants, opening an avenue for exploring the mechanism for the association of light-harvesting complexes with the PSII core complexes.photosynthesis | photoinhibition P hotosystem II (PSII) consists of more than 20 subunits. Assembly of this photosystem is a multistep process that functions in a highly coordinated fashion (1-3). The process starts with PSII initiation complexes (D2, PsbE, PsbF, and PsbI), and then D1 and CP47 are sequentially recruited to form CP47-RC complexes, followed by addition of PsbH, PsbM, PsbTc, and PsbR subunits. Next, CP43 and other subunits are added to generate PSII monomers, which develop into PSII dimers. Finally, lightharvesting complex (LHC) II is attached to form PSII supercomplexes. The D1 protein of PSII is prone to photodamage under excessive light conditions (4). To sustain photosynthesis, damaged D1 protein is degraded and replaced with a newly synthesized copy via PSII repair-a highly complex and critical process whose mechanism remains unclear (3, 4).In most oxygen-evolving photosynthetic organisms, D1 protein is synthesized as a precursor (pD1) with a C-terminal tail. The pD1 protein is integrated into the thylakoid membrane and forms the initial PSII reaction center combined with other PSII

show abstract

“…CYP38 was proposed to guide the folding of D1 and presumably CP43 into PSII, a prerequisite for proper assembly of the water-splitting apparatus . Psb29 and the immonophilin FKBP20-2 are required for efficient assembly of PSII supercomplexes (Keren et al, 2005;Lima et al, 2006;Fu et al, 2007). LPA2 and LPA3 cooperate with each other and interact with ALB3 in assisting incorporation and stabilization of CP43 (Ossenbühl et al, 2004;Cai et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

PsbN Is Required for Assembly of the Photosystem II Reaction Center in Nicotiana tabacum

et al. 2014

View full text Add to dashboard Cite

ORCID ID: 0000-0003-2973-9514 (J.M.)The chloroplast-encoded low molecular weight protein PsbN is annotated as a photosystem II (PSII) subunit. To elucidate the localization and function of PsbN, encoded on the opposite strand to the psbB gene cluster, we raised antibodies and inserted a resistance cassette into PsbN in both directions. Both homoplastomic tobacco (Nicotiana tabacum) mutants ΔpsbN-F and ΔpsbN-R show essentially the same PSII deficiencies. The mutants are extremely light sensitive and failed to recover from photoinhibition. Although synthesis of PSII proteins was not altered significantly, both mutants accumulated only ;25% of PSII proteins compared with the wild type. Assembly of PSII precomplexes occurred at normal rates, but heterodimeric PSII reaction centers (RCs) and higher order PSII assemblies were not formed efficiently in the mutants. The ΔpsbN-R mutant was complemented by allotopic expression of the PsbN gene fused to the sequence of a chloroplast transit peptide in the nuclear genome. PsbN represents a bitopic trans-membrane peptide localized in stroma lamellae with its highly conserved C terminus exposed to the stroma. Significant amounts of PsbN were already present in dark-grown seedling. Our data prove that PsbN is not a constituent subunit of PSII but is required for repair from photoinhibition and efficient assembly of the PSII RC.

show abstract

A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana

Cited by 154 publications

References 40 publications

PSB27: A thylakoid protein enabling Arabidopsis to adapt to changing light intensity

PSB27: A thylakoid protein enabling Arabidopsis to adapt to changing light intensity

C-terminal processing of reaction center protein D1 is essential for the function and assembly of photosystem II inArabidopsis

PsbN Is Required for Assembly of the Photosystem II Reaction Center in Nicotiana tabacum

Contact Info

Product

Resources

About