PDBsum entry: 1kbf

Signaling protein

PDB-id: 1kbf

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PROCHECK

Protein chain

49 a.a. *

Metal ions

_ZN ×2

* Residue conservation analysis

Tools

Clefts Calculation

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PDB id:

1kbf

Name:

Signaling protein

Title:

Solution structure of the cysteine-rich c1 domain of kinase suppressor of ras

Structure:

Kinase suppressor of ras. Chain: a. Fragment: cysteine-rich c1 domain (residues 330-378). Engineered: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Gene: ksr1. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

UniProt:

Q61097 (KSR1_MOUSE)

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

873 a.a.

Struc:

49 a.a.*

Key:	PfamA domain	PfamB domain
Secondary structure	CATH domain

* PDB and UniProt seqs differ at 1 residue position (black cross)

Resolution:

not givenÅ

NMR structure:

20 models

Authors:

M.Zhou,D.A.Horita,D.S.Waugh,R.A.Byrd,D.K.Morrison

Key ref:

M.Zhou et al. (2002). Solution structure and functional analysis of the cysteine-rich C1 domain of kinase suppressor of Ras (KSR).. J Mol Biol, 315, 435-446. [PubMed id: 11786023] [DOI: 10.1006/jmbi.2001.5263]

Date:

06-Nov-01

Release date:

23-Jan-02

Related entries:

1kbe
1kbe is the structure with the lowest energy

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Procheck

Clefts

Surface

Key reference

DOI no: 10.1006/jmbi.2001.5263

J Mol Biol 315:435-446 (2002)

PubMed id: 11786023

Solution structure and functional analysis of the cysteine-rich C1 domain of kinase suppressor of Ras (KSR).

M.Zhou, D.A.Horita, D.S.Waugh, R.A.Byrd, D.K.Morrison.

ABSTRACT

Kinase suppressor of Ras (KSR) is a conserved component of the Ras pathway that acts as a molecular scaffold to promote signal transmission from Raf-1 to MEK and MAPK. All KSR proteins contain a conserved cysteine-rich C1 domain, and studies have implicated this domain in the regulation of KSR1 subcellular localization and function. To further elucidate the biological role of the KSR1 C1 domain, we have determined its three-dimensional solution structure using nuclear magnetic resonance (NMR). We find that while the overall topology of the KSR1 C1 domain is similar to the C1 domains of Raf-1 and PKCgamma, the predicted ligand-binding region and the surface charge distribution are unique. Moreover, by generating chimeric proteins in which these domains have been swapped, we find that the C1 domains of Raf-1, PKCgamma, and KSR1 are not functionally interchangeable. The KSR1 C1 domain does not bind with high affinity or respond biologically to phorbol esters or ceramide, and it does not interact directly with Ras, indicating that the putative ligand(s) for the KSR1 C1 domain are distinct from those that interact with PKCgamma and Raf-1. In addition, our analysis of the chimeric proteins supports the model that Raf-1 is a ceramide-activated kinase and that its C1 domain is involved in the ceramide-mediated response. Finally, our findings demonstrate an absolute requirement of the KSR1 C1 domain in mediating the membrane localization of KSR1, a crucial feature of its scaffolding activity. Together, these results underscore the functional specificity of these important regulatory domains and demonstrate that the structural features of the C1 domains can provide valuable insight into their ligand-binding properties.

Selected figure(s)

Figure 2.
Figure 2. Comparison of the KSR1, Raf-1, and PKCg C1 domains. (a) Protein backbone superposition of 11 lowest-energy structures of the KSR1 C1 (residues 331-378), Raf-1 C1 (residues 136-187;[14] Protein Data Bank accession code 1FAQ), and PKCg C1b domains (residues 100-153; [15] Protein Data Bank accession code 1TBO). The flexible regions containing residues with large RMSD values are colored in white. The two Zn ions coordinated in the KSR1 C1 domain are depicted as yellow spheres. (b) Ribbon diagram of the KSR1, Raf-1 (Protein Data Bank accession code 1FAR), and PKCg C1b (Protein Data Bank accession code 1TBN) domains. Arrows indicate the loops predicted to be involved in ligand binding. (c) Amino acid sequences of the KSR1, Raf-1, and PKCg C1b domains. The conserved cysteine and histidine residues that coordinate the Zn ions are shown in red.

Figure 3.
Figure 3. Comparison of the predicted ligand binding regions of the atypical KSR1 (a) and Raf-1 (b) C1 domains. Ribbon diagrams are depicted on the left with the side-chains of hydrophobic residues shown in magenta and the side-chains of hydrophilic residues shown in green. Surface charge diagrams are shown on the right with positive charges in blue, negative charges in red, and neutral charges in white. The diagrams were generated by MOLMOL[51]. A red arrow indicates the positively charged lysine residue found in the b1-b2 loop of the Raf-1 C1 domains and black arrows indicate the Ras-binding site of the Raf-1 C1 domain. and the predicted ligand-binding region of the KSR1 C1 domain.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2002, 315, 435-446) copyright 2002.

Figures were selected by an automated process.