The precursor of PsaD assembles into the photosystem I complex in two steps.
AUTOR(ES)
Minai, L
RESUMO
The present study addresses the assembly in the chloroplast thylakoid membranes of PsaD, a peripheral membrane protein of the photosystem I complex. Located on the stromal side of the thylakoids, PsaD was found to assemble in vitro into the membranes in its precursor (pre-PsaD) and also in its mature (PsaD) form. Newly assembled unprocessed pre-PsaD was resistant to NaBr and alkaline wash. Yet it was sensitive to proteolytic digestion. In contradistinction, when the assembled precursor was processed, the resulting mature PsaD was resistant to proteases to the same extent as endogenous [correction of endogeneous] PsaD. The accumulation of protease-resistant PsaD in the thylakoids correlated with the increase of mature-PsaD in the membranes. This protection of mature PsaD from proteolysis could not be observed when PsaD was in a soluble form-i.e. not assembled within the thylakoids. The data suggest that pre-PsaD assembles to the membranes and only in a second step processing takes place. The observation that the assembly of pre-PsaD is affected by salts to a much lesser extent than that of mature-PsaD supports a two-step assembly of pre-PsaD.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=39023Documentos Relacionados
- The PsaD subunit of photosystem I. Mutations in the basic domain reduce the level of PsaD in the membranes.
- Multiple Functions for the C Terminus of the PsaD Subunit in the Cyanobacterial Photosystem I Complex
- Organization of Photosystem I Polypeptides (A Structural Interaction between the PsaD and PsaL Subunits).
- Cloning and sequencing of a cDNA clone encoding the photosystem I PsaD subunit from Chlamydomonas reinhardtii.
- Organization of photosystem I polypeptides. Identification of PsaB domains that may interact with PsaD.