The University of Southampton
University of Southampton Institutional Repository

The GTPase cycle of the chloroplast import receptors Toc33/Toc34: implications from monomeric and dimeric structures

The GTPase cycle of the chloroplast import receptors Toc33/Toc34: implications from monomeric and dimeric structures
The GTPase cycle of the chloroplast import receptors Toc33/Toc34: implications from monomeric and dimeric structures
Transport of precursor proteins across chloroplast membranes involves the GTPases Toc33/34 and Toc159 at the outer chloroplast envelope. The small GTPase Toc33/34 can homodimerize, but the regulation of this interaction has remained elusive. We show that dimerization is independent of nucleotide loading state, based on crystal structures of dimeric Pisum sativum Toc34 and monomeric Arabidopsis thaliana Toc33. An arginine residue is--in the dimer--positioned to resemble a GAP arginine finger. However, GTPase activation by dimerization is sparse and active site features do not explain catalysis, suggesting that the homodimer requires an additional factor as coGAP. Access to the catalytic center and an unusual switch I movement in the dimeric structure support this finding. Potential binding sites for interactions within the Toc translocon or with precursor proteins can be derived from the structures.
0969-2126
585-96
Koenig, Patrick
e03428c5-67ef-4df4-9310-77190d216517
Oreb, Mislav
85bcf606-2b7c-4362-a88f-b99bf6cbe748
Höfle, Anja
d0ed5ed6-54c6-47e8-8e1a-db9244d03e23
Kaltofen, Sabine
6f59930d-2655-4ba0-b7e9-3fc31d41e2b8
Rippe, Karsten
5dc8f1ed-943d-42d2-baa6-1e7f777f391e
Sinning, Irmgard
fbc3f199-8a3b-47a6-9ee7-00bfc472e079
Schleiff, Enrico
119114bb-9cbb-45e9-a161-db45b1e9f4ba
Tews, Ivo
9117fc5e-d01c-4f8d-a734-5b14d3eee8dd
Koenig, Patrick
e03428c5-67ef-4df4-9310-77190d216517
Oreb, Mislav
85bcf606-2b7c-4362-a88f-b99bf6cbe748
Höfle, Anja
d0ed5ed6-54c6-47e8-8e1a-db9244d03e23
Kaltofen, Sabine
6f59930d-2655-4ba0-b7e9-3fc31d41e2b8
Rippe, Karsten
5dc8f1ed-943d-42d2-baa6-1e7f777f391e
Sinning, Irmgard
fbc3f199-8a3b-47a6-9ee7-00bfc472e079
Schleiff, Enrico
119114bb-9cbb-45e9-a161-db45b1e9f4ba
Tews, Ivo
9117fc5e-d01c-4f8d-a734-5b14d3eee8dd

Koenig, Patrick, Oreb, Mislav, Höfle, Anja, Kaltofen, Sabine, Rippe, Karsten, Sinning, Irmgard, Schleiff, Enrico and Tews, Ivo (2008) The GTPase cycle of the chloroplast import receptors Toc33/Toc34: implications from monomeric and dimeric structures. Structure, 16 (4), 585-96. (doi:10.1016/j.str.2008.01.008). (PMID:18400179)

Record type: Article

Abstract

Transport of precursor proteins across chloroplast membranes involves the GTPases Toc33/34 and Toc159 at the outer chloroplast envelope. The small GTPase Toc33/34 can homodimerize, but the regulation of this interaction has remained elusive. We show that dimerization is independent of nucleotide loading state, based on crystal structures of dimeric Pisum sativum Toc34 and monomeric Arabidopsis thaliana Toc33. An arginine residue is--in the dimer--positioned to resemble a GAP arginine finger. However, GTPase activation by dimerization is sparse and active site features do not explain catalysis, suggesting that the homodimer requires an additional factor as coGAP. Access to the catalytic center and an unusual switch I movement in the dimeric structure support this finding. Potential binding sites for interactions within the Toc translocon or with precursor proteins can be derived from the structures.

Text
Structure_16-585.pdf - Version of Record
Restricted to Repository staff only
Request a copy
Text
Structure_16-585-supplement.pdf - Other
Download (630kB)
Text
Structure_16-585-cover-reduced.pdf - Other
Restricted to Repository staff only
Request a copy

More information

Published date: April 2008
Organisations: Centre for Biological Sciences

Identifiers

Local EPrints ID: 200535
URI: http://eprints.soton.ac.uk/id/eprint/200535
ISSN: 0969-2126
PURE UUID: d9e1d25a-7c82-4855-af0a-5aa62101fb2f
ORCID for Ivo Tews: ORCID iD orcid.org/0000-0002-4704-1139

Catalogue record

Date deposited: 26 Oct 2011 11:05
Last modified: 15 Mar 2024 03:36

Export record

Altmetrics

Contributors

Author: Patrick Koenig
Author: Mislav Oreb
Author: Anja Höfle
Author: Sabine Kaltofen
Author: Karsten Rippe
Author: Irmgard Sinning
Author: Enrico Schleiff
Author: Ivo Tews ORCID iD

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×