PDBsum entry: 1x32

Signaling protein

PDB id: 1x32

Contents

Protein chain

47 a.a.

PDB id:

1x32

Name:

Signaling protein

Title:

Three dimensional solution structure of the chromo1 domain of cpsrp43

Structure:

Chloroplast signal recognition particle component. Chain: a. Fragment: chromo domain 1. Synonym: cpsrp43, cao. Engineered: yes

Source:

Arabidopsis thaliana. Thale cress. Organism_taxid: 3702. Expressed in: escherichia coli. Expression_system_taxid: 562

NMR struc:

20 models

Authors:

V.Sivaraja,T.K.Kumar,R.Henry,C.Yu

Key ref:

V.Sivaraja et al. (2005). Three-dimensional solution structures of the chromodomains of cpSRP43. J Biol Chem, 280, 41465-41471. PubMed id: 16183644 DOI: 10.1074/jbc.M507077200

Date:

28-Apr-05 Release date: 20-Sep-05

Protein chain

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

Seq: 373 a.a.

Struc: 47 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Cellular component: nucleus (2 terms)
• Biological process: chromatin assembly or disassembly (1 term)
• Biochemical function: chromatin binding (1 term)

DOI no: 10.1074/jbc.M507077200

J Biol Chem 280:41465-41471 (2005)

PubMed id: 16183644

Three-dimensional solution structures of the chromodomains of cpSRP43.

V.Sivaraja, T.K.Kumar, P.S.Leena, A.N.Chang, C.Vidya, R.L.Goforth, D.Rajalingam, K.Arvind, J.L.Ye, J.Chou, R.Henry, C.Yu.

ABSTRACT

Chloroplasts contain a unique signal recognition particle (cpSRP). Unlike the cytoplasmic forms, the cpSRP lacks RNA but contains a conserved 54-kDa GTPase and a novel 43-kDa subunit (cpSRP43). Recently, three functionally distinct chromodomains (CDs) have been identified in cpSRP43. In the present study, we report the three-dimensional solution structures of the three CDs (CD1, CD2, and CD3) using a variety of triple resonance NMR experiments. The structure of CD1 consists of a triple-stranded beta-sheet segment. The C-terminal helical segment typically found in the nuclear chromodomains is absent in CD1. The secondary structural elements in CD2 and CD3 include a triple-stranded antiparallel beta-sheet and a C-terminal helix. Interestingly, the orientation of the C-terminal helix is significantly different in the structures of CD2 and CD3. Critical comparison of the structures of the chromodomains of cpSRP43 with those found in nuclear chromodomain proteins revealed that the diverse protein-protein interactions mediated by the CDs appear to stem from the differences that exist in the surface charge potentials of each CD. Results of isothermal titration calorimetry experiments confirmed that only CD2 is involved in binding to cpSRP54. The negatively charged C-terminal helix in CD2 possibly plays a crucial role in the cpSRP54-cpSRP43 interaction.

Selected figure(s)

Figure 2.
FIGURE 2. 1H-15N HSQC spectra of CDs from cpSRP43.

Figure 4.
FIGURE 4. Depiction of the distribution of charged residues and the hydrophobic (green) clusters in the three-dimensional structures of CD1, CD2, and CD3. The structure of CD2 shows two hydrophobic clusters encompassed by negatively charged residues (red). The hydrophobic core formed around Trp29 (W29) is enclosed by two layers of charged residues. The layer bordering the hydrophobic core is comprised of positively charged residues (blue).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 41465-41471) copyright 2005.

Figures were selected by an automated process.