Proteomic Amino-Termini Profiling Reveals Targeting Information for Protein Import into Complex Plastids

In organisms with complex plastids acquired by secondary endosymbiosis from a photosynthetic eukaryote, the majority of plastid proteins are nuclear-encoded, translated on cytoplasmic ribosomes, and guided across four membranes by a bipartite targeting sequence. In-depth understanding of this vital import process has been impeded by a lack of information about the transit peptide part of this sequence, which mediates transport across the inner three membranes. We determined the mature N-termini of hundreds of proteins from the model diatom Thalassiosira pseudonana, revealing extensive N-terminal modification by acetylation and proteolytic processing in both cytosol and plastid. We identified 63 mature N-termini of nucleus-encoded plastid proteins, deduced their complete transit peptide sequences, determined a consensus motif for their cleavage by the stromal processing peptidase, and found evidence for subsequent processing by a plastid methionine aminopeptidase. The cleavage motif differs from that of higher plants, but is shared with other eukaryotes with complex plastids.

Alami, Meriem (författare)
Lange, Philipp F. (författare)
Foster, Leonard J. (författare)
Schröder, Wolfgang P.Umeå universitet,Kemiska institutionen(Swepub:umu)wosc0001 (författare)
Overall, Christopher M. (författare)
Green, Beverley R. (författare)
Umeå universitetKemiska institutionen (creator_code:org_t)

Av författaren/redakt...: Huesgen, Pitter ...; Alami, Meriem; Lange, Philipp F ...; Foster, Leonard ...; Schröder, Wolfga ...; Overall, Christo ...; visa fler...; Green, Beverley ...; visa färre...

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