1H65

Crystal structure of pea Toc34 - a novel GTPase of the chloroplast protein translocon

Summary for 1H65

• Entry DOI: 10.2210/pdb1h65/pdb
• Descriptor: CHLOROPLAST OUTER ENVELOPE PROTEIN OEP34, GUANOSINE-5'-DIPHOSPHATE, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: gtpase, chloroplast, translocon
• Biological source: PISUM SATIVUM (GARDEN PEA)
• Total number of polymer chains: 3
• Total formula weight: 90722.47

Authors

Sun, Y.J.,Forouhar, F.,Li, H.M.,Tu, S.L.,Kao, S.,Shr, H.L.,Chou, C.C.,Hsiao, C.D. (deposition date: 2001-06-06, release date: 2002-01-29, Last modification date: 2024-11-13)

Primary citation

Sun, Y.J.,Forouhar, F.,Li, H.M.,Tu, S.L.,Yeh, Y.H.,Kao, S.,Shr, H.L.,Chou, C.C.,Chen, C.,Hsiao, C.D.
Crystal Structure of Pea Toc34 - a Novel Gtpase of the Chloroplast Protein Translocon
Nat.Struct.Biol., 9:95-, 2002

PubMed Abstract: Toc34, a 34-kDa integral membrane protein, is a member of the Toc (translocon at the outer-envelope membrane of chloroplasts) complex, which associates with precursor proteins during protein transport across the chloroplast outer membrane. Here we report the 2.0 A resolution crystal structure of the cytosolic part of pea Toc34 in complex with GDP and Mg2+. In the crystal, Toc34 molecules exist as dimers with features resembling those found in a small GTPase in complex with a GTPase activating protein (GAP). However, gel filtration experiments revealed that dimeric and monomeric forms of Toc34 coexisted in phosphate saline buffer solution at pH 7.2. Mutation of Arg 128, an essential residue for dimerization, to an Ala residue led to the formation of an exclusively monomeric species whose GTPase activity is significantly reduced compared to that of wild type Toc34. These results, together with a number of structural features unique to Toc34, suggest that each monomer acts as a GAP on the other interacting monomer.

PubMed: 11753431
DOI: 10.1038/NSB744

Experimental method

X-RAY DIFFRACTION (2 Å)