Arabidopsis Nuclear-Encoded Plastid Transit Peptides Contain Multiple Sequence Subgroups with Distinctive Chloroplast-Targeting Sequence Motifs

• Published in: The Plant cell 2008-06, Vol.20 (6), p.1603-1622
• Main Authors: Lee, Dong Wook, Kim, Jong Kyoung, Lee, Sumin, Choi, Seungjin, Kim, Sanguk, Hwang, Inhwan
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Amino acids; Antibodies; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Bioinformatics; Blotting, Western; Cell Nucleus - genetics; Cell Nucleus - metabolism; Chloroplasts; Chloroplasts - metabolism; Gels; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Imports; Molecular Sequence Data; Peptides; Plant cells; Plastids; Plastids - metabolism; Polymerase Chain Reaction; Protein precursors; Protein Transport; Proteins; Protoplasts; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Homology, Amino Acid
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.108.060541

The N-terminal transit peptides of nuclear-encoded plastid proteins are necessary and sufficient for their import into plastids, but the information encoded by these transit peptides remains elusive, as they have a high sequence diversity and lack consensus sequences or common sequence motifs. Here, we investigated the sequence information contained in transit peptides. Hierarchical clustering on transit peptides of 208 plastid proteins showed that the transit peptide sequences are grouped to multiple sequence subgroups. We selected representative proteins from seven of these multiple subgroups and confirmed that their transit peptide sequences are highly dissimilar. Protein import experiments revealed that each protein contained transit peptide-specific sequence motifs critical for protein import into chloroplasts. Bioinformatics analysis identified sequence motifs that were conserved among members of the identified subgroups. The sequence motifs identified by the two independent approaches were nearly identical or significantly overlapped. Furthermore, the accuracy of predicting a chloroplast protein was greatly increased by grouping the transit peptides into multiple sequence subgroups. Based on these data, we propose that the transit peptides are composed of multiple sequence subgroups that contain distinctive sequence motifs for chloroplast targeting.