Molecular Studies of CtpA, the Carboxyl-terminal Processing Protease for the D1 Protein of the Photosystem II Reaction Center in Higher Plants

Oelmüller, Ralf; Herrmann, Reinhold G.; Pakrasi, Himadri B.

doi:10.1074/jbc.271.36.21848

Cited by 94 publications

(54 citation statements)

References 39 publications

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“…Based on this observation, we conclude that the processing of pD1 is lightdependent: under high light, the D1 turnover rate is high and so is pD1 processing; under low light, D1 turnover is slow and pD1 processing also slows down. This is in agreement with previous work (28).…”

Section: Defect In C-terminal Processing Renders Mutant Plants Hyperssupporting

confidence: 83%

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.

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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

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Section: Defect In C-terminal Processing Renders Mutant Plants Hyperssupporting

confidence: 83%

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.

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“…Nevertheless, to date, there are no experimental data to support this possibility. Another protease found in the lumen, CtpA, is probably not involved in D1 degradation, as its activity is most likely limited to C-terminal processing of the pre-D1 protein as a prerequisite for its assembly into the functional PSII complex (Oelmuller et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

The Thylakoid Lumen Protease Deg1 Is Involved in the Repair of Photosystem II from Photoinhibition in Arabidopsis

2007

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Deg1 is a Ser protease peripherally attached to the lumenal side of the thylakoid membrane. Its physiological function is unknown, but its localization makes it a suitable candidate for participation in photoinhibition repair by degradation of the photosystem II reaction center protein D1. We transformed Arabidopsis thaliana with an RNA interference construct and obtained plants with reduced levels of Deg1. These plants were smaller than wild-type plants, flowered earlier, were more sensitive to photoinhibition, and accumulated more of the D1 protein, probably in an inactive form. Two C-terminal degradation products of the D1 protein, of 16 and 5.2 kD, accumulated at lower levels compared with the wild type. Moreover, addition of recombinant Deg1 to inside-out thylakoid membranes isolated from the mutant could induce the formation of the 5.2-kD D1 C-terminal fragment, whereas the unrelated proteases trypsin and thermolysin could not. Immunoblot analysis revealed that mutants containing less Deg1 also contain less FtsH protease, and FtsH mutants contain less Deg1. These results suggest that Deg1 cooperates with the stroma-exposed proteases FtsH and Deg2 in degrading D1 protein during repair from photoinhibition by cleaving lumen-exposed regions of the protein. In addition, they suggest that accumulation of Deg1 and FtsH proteases may be coordinated.

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“…Homologues of bacterial htrA and tsp enzymes have been shown previously in humans (I. Ohno, J. Hashimoto, K. Takaoka, 0. Takahiro, K. Okubo, K. Matsubara, unpublished, EMBO code D87258) and in higher plants (Oelmiiller et al, 1996), respectively.…”

Section: Novel Bacterial Yeast and Plant Pdzsmentioning

confidence: 99%

Evidence for PDZ domains in bacteria, yeast, and plants

1997

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Several dozen signaling proteins are now known to contain 80-100 residue repeats, called PDZ (or DHR or GLGF) domains, several of which interact with the C-terminal tetrapeptide motifs X-Ser/Thr-X-Val-COO-of ion channels and/or receptors. PDZ domains have previously been noted only in mammals, flies, and worms, suggesting that the primordial PDZ domain arose relatively late in eukaryotic evolution. Here, techniques of sequence analysis-including local alignment, profile, and motif database searches-indicate that PDZ domain homologues are present in yeast, plants, and bacteria. It is suggested that two PDZ domains occur in bacterial high-temperature requirement A (htrA) and one in tail-specific protease (tsp) homologues, and that a yeast htrA homologue contains four PDZ domains. Sequence comparisons suggest that the spread of PDZ domains in these diverse organisms may have occurred via horizontal gene transfer. The known affinity of Escherichia coli tsp for C-terminal polypeptides is proposed to be mediated by its PDZ-like domain, in a similar manner to the binding of C-terminal polypeptides by animal PDZ domains.

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Molecular Studies of CtpA, the Carboxyl-terminal Processing Protease for the D1 Protein of the Photosystem II Reaction Center in Higher Plants

Cited by 94 publications

References 39 publications

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

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

The Thylakoid Lumen Protease Deg1 Is Involved in the Repair of Photosystem II from Photoinhibition in Arabidopsis

Evidence for PDZ domains in bacteria, yeast, and plants

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