Abstract/Details

The role of Toc receptor interactions in controlling protein import into chloroplasts


2009 2009

Other formats: Order a copy

Abstract (summary)

Nuclear-encoded chloroplast proteins are synthesized as precursors in the cytosol with N-terminal cleavable transit peptides. The post translational import of proteins into chloroplasts occurs first through the outer membrane via the Toc complex (Translocon of Outer membrane of Chloroplast). The high fidelity of the protein import process is maintained by the specific recognition of the transit peptide of nucleus-encoded proteins by the coordinate activities of two homologous GTPase Toc receptors, Toc34 and Toc159. Structural and biochemical studies suggest that dimerization of the Toc receptors functions as a component of the mechanism to control access of preproteins to the membrane translocation channel of the translocon chloroplast envelope. I show that specific mutations that disrupt receptor dimerization in vitro reduce the rate of protein import in transgenic Arabidopsis compared to the wild type receptor. The mutations do not affect the GTPase activities of the receptors. Interestingly, these mutations do not disrupt initial preprotein binding at the receptors, but they reduce the efficiency of the transition from preprotein binding to membrane translocation. These data indicate that dimerization of receptors has a direct role in protein import, and support a hypothesis in which conformational changes that initiate membrane translocation of chloroplast preproteins is part of the molecular mechanism of GTP-regulated protein import.

Indexing (details)


Subject
Plant biology
Classification
0309: Plant biology
Identifier / keyword
Biological sciences; Arabidopsis; Chlroplasts; Dimerization; Protein import; Receptor interactions; Toc
Title
The role of Toc receptor interactions in controlling protein import into chloroplasts
Author
Lee, Jeonghwa
Number of pages
109
Publication year
2009
Degree date
2009
School code
0118
Source
DAI-B 70/12, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9781109500523
Advisor
Schnell, Danny J.
Committee member
Bezanilla, Magdalena; Garman, Scott C.; Normanly, Jennifer
University/institution
University of Massachusetts Amherst
Department
Biochemistry
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3379979
ProQuest document ID
304922629
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304922629
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.