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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2011-7-28
pubmed:abstractText
Chloroplast precursor proteins encoded in the nucleus depend on their targeting sequences for delivery to chloroplasts. There exist different routes to the chloroplast outer envelope, but a common theme is the involvement of molecular chaperones. Hsp90 (heat-shock protein 90) delivers precursors via its receptor Toc64, which transfers precursors to the core translocase in the outer envelope. In the present paper, we identify an uncharacterized protein in Arabidopsis thaliana OEP61 which shares common features with Toc64, and potentially provides an alternative route to the chloroplasts. Sequence analysis indicates that OEP61 possesses a clamp-type TPR (tetratricopeptide repeat) domain capable of binding molecular chaperones, and a C-terminal TMD (transmembrane domain). Phylogenetic comparisons show sequence similarities between the TPR domain of OEP61 and those of the Toc64 family. Expression of mRNA and protein was detected in all plant tissues, and localization at the chloroplast outer envelope was demonstrated by a combination of microscopy and in vitro import assays. Binding assays show that OEP61 interacts specifically with Hsp70 (heat-shock protein 70) via its TPR clamp domain. Furthermore, OEP61 selectively recognizes chloroplast precursors via their targeting sequences, and a soluble form of OEP61 inhibits chloroplast targeting. We therefore propose that OEP61 is a novel chaperone receptor at the chloroplast outer envelope, mediating Hsp70-dependent protein targeting to chloroplasts.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1470-8728
pubmed:author
pubmed:copyrightInfo
© The Authors Journal compilation © 2011 Biochemical Society
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
438
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
143-53
pubmed:meshHeading
pubmed-meshheading:21612577-Amino Acid Sequence, pubmed-meshheading:21612577-Arabidopsis, pubmed-meshheading:21612577-Arabidopsis Proteins, pubmed-meshheading:21612577-Blotting, Western, pubmed-meshheading:21612577-Chloroplasts, pubmed-meshheading:21612577-DNA, Plant, pubmed-meshheading:21612577-HSP70 Heat-Shock Proteins, pubmed-meshheading:21612577-Molecular Chaperones, pubmed-meshheading:21612577-Molecular Sequence Data, pubmed-meshheading:21612577-Phylogeny, pubmed-meshheading:21612577-Plastids, pubmed-meshheading:21612577-Protein Binding, pubmed-meshheading:21612577-Protein Biosynthesis, pubmed-meshheading:21612577-RNA, Messenger, pubmed-meshheading:21612577-RNA, Plant, pubmed-meshheading:21612577-Reverse Transcriptase Polymerase Chain Reaction, pubmed-meshheading:21612577-Sequence Homology, Amino Acid, pubmed-meshheading:21612577-Transcription, Genetic
pubmed:year
2011
pubmed:articleTitle
OEP61 is a chaperone receptor at the plastid outer envelope.
pubmed:affiliation
Biomedical Research Centre, Sheffield Hallam University, Sheffield S1 1WB, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't