PDBsum entry 3deo

Protein transport, membrane protein

PDB id: 3deo

Contents

Protein chain

183 a.a. *

Metals

_MG

Waters ×229

* Residue conservation analysis

PDB id:

3deo

Name:

Protein transport, membrane protein

Title:

Structural basis for specific substrate recognition by the chloroplast signal recognition particle protein cpsrp43

Structure:

Signal recognition particle 43 kda protein. Chain: a. Fragment: residues 85-267. Synonym: chromo protein srp43, cpsrp43. Engineered: yes

Source:

Arabidopsis thaliana. Mouse-ear cress. Organism_taxid: 3702. Gene: cao, at2g47450, t30b22.25. Expressed in: escherichia coli

Resolution:

1.50Å R-factor: 0.171 R-free: 0.211

Authors:

K.F.Stengel,K.Wild,I.Sinning

Key ref:

K.F.Stengel et al. (2008). Structural basis for specific substrate recognition by the chloroplast signal recognition particle protein cpSRP43. Science, 321, 253-256. PubMed id: 18621669 DOI: 10.1126/science.1158640

Date:

10-Jun-08 Release date: 12-Aug-08

Protein chain

O22265  (SR43C_ARATH) -  Signal recognition particle 43 kDa protein, chloroplastic from Arabidopsis thaliana

Seq: 373 a.a.

Struc: 183 a.a.

DOI no: 10.1126/science.1158640

Science 321:253-256 (2008)

PubMed id: 18621669

Structural basis for specific substrate recognition by the chloroplast signal recognition particle protein cpSRP43.

K.F.Stengel, I.Holdermann, P.Cain, C.Robinson, K.Wild, I.Sinning.

ABSTRACT

Secretory and membrane proteins carry amino-terminal signal sequences that, in cotranslational targeting, are recognized by the signal recognition particle protein SRP54 without sequence specificity. The most abundant membrane proteins on Earth are the light-harvesting chlorophyll a/b binding proteins (LHCPs). They are synthesized in the cytoplasm, imported into the chloroplast, and posttranslationally targeted to the thylakoid membrane by cpSRP, a heterodimer formed by cpSRP54 and cpSRP43. We present the 1.5 angstrom crystal structure of cpSRP43 characterized by a unique arrangement of chromodomains and ankyrin repeats. The overall shape and charge distribution of cpSRP43 resembles the SRP RNA, which is absent in chloroplasts. The complex with the internal signal sequence of LHCPs reveals that cpSRP43 specifically recognizes a DPLG peptide motif. We describe how cpSPR43 adapts the universally conserved SRP system to posttranslational targeting and insertion of the LHCP family of membrane proteins.

Selected figure(s)

Figure 1.
Fig. 1. Structure of cpSRP43. (A) Scheme of the domain structure of cpSRP43 with chromodomains (CD1 to 3) and ankyrin repeats (Ank1 to 4). Domains present in the crystal structure are given by residue numbers and are indicated in rainbow colors. (B) Side view of cpSRP43 in ribbon representation. The domains are labeled. (C) Side view of cpSRP43 [90° rotation with respect to (B)]. Secondary structure elements are numbered. The N- and C-termini are labeled. (D) Front view of cpSRP43. The surface representation shows two hydrophobic grooves separated by a positive ridge. The molecular surface is colored blue and red according to positive and negative electrostatic potential, respectively. The asterisk highlights Tyr^204 in Ank3. (E) Back view of cpSRP43 [same view as in (C)] showing the highly negatively charged surface with a spacing of negative charges reminiscent of RNA (see fig. S2).

Figure 2.
Fig. 2. Structure of the cpSRP43/L18p complex. (A) LHCP topology with three transmembrane helices (TM1 to 3). The sequence of the L18 region is given for the major LHCP, Lhcb1 from Pisum sativum, which was used in this study (red, the DPLG motif is underlined). TM3 starts immediately after the L18 region. (B) Typical isothermal titration calorimetry (ITC) experiment of the cpSRP43 interaction with L18p. (C) Ribbon representation of cpSRP43 (blue) with bound L18p (as a ball-and-stick model, gray). The N- and C-termini are indicated. (D) Surface representation of the cpSRP43/L18p complex. The peptide (labeled by residue numbers) binds in the hydrophobic groove 1. Four residues at the N terminus and two residues at the C terminus are not resolved.

The above figures are reprinted by permission from the AAAs: Science (2008, 321, 253-256) copyright 2008.

Figures were selected by an automated process.