Abstract
The 33-, 23-, and 16-kDa proteins of the photosynthetic oxygen-evolving complex are synthesized as precursors in the cytoplasm and transported into the thylakoid lumen of higher plant chloroplasts. In this report we have analyzed the import and maturation of these precursors, using reconstituted protein import assays and partially purified preparations of the processing peptidases involved. Precursors of the 33- and 23-kDa proteins from Spinacia and Triticum aestivum are processed by a stromal peptidase to intermediate forms; polypeptides of similar size are observed during the transport of these precursors and possibly that of the 16-kDa protein, into isolated chloroplasts. Complete maturation of the 33- and 23-kDa proteins is carried out by a thylakoidal peptidase shown previously to be involved in plastocyanin biogenesis. The data support an import mechanism involving successive cleavages by the stromal and thylakoidal processing peptidases.
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Claims 4
Claim · model-written summary
Spinacia and Triticum aestivum 33- and 23-kDa protein precursors were processed to intermediates by stromal peptidase.
- Taxon
- Spinacia and Triticum aestivum
Spinacia
Triticum aestivume0 - Organ / stage
- stromale0
- Gene
- 33- and 23-kDa proteinse0
- Outcome
- processed by a stromal peptidase to intermediate formse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Precursors of the 33- and 23-kDa proteins from Spinacia and Triticum aestivum are processed by a stromal peptidase to intermediate forms”
Claim · model-written summary
Similarly sized polypeptides were observed during transport of the 33- and 23-kDa precursors into isolated chloroplasts.
Verbatim
e0“polypeptides of similar size are observed during the transport of these precursors and possibly that of the 16-kDa protein, into isolated chloroplasts”
e1“higher plant chloroplasts”
Claim · model-written summary
A thylakoidal peptidase completed maturation of the 33- and 23-kDa proteins.
Verbatim
e0“Complete maturation of the 33- and 23-kDa proteins is carried out by a thylakoidal peptidase”
e1“higher plant chloroplasts”
Claim · model-written summary
The authors infer successive stromal and thylakoidal peptidase cleavages in the import mechanism.
Verbatim
e0“The data support an import mechanism involving successive cleavages by the stromal and thylakoidal processing peptidases”
e1“higher plant chloroplasts”