PDBsum entry 1f9w

Contractile protein

PDB id: 1f9w

Contents

Protein chains

300 a.a. *

Ligands

ADP ×2

Metals

_MG ×2

Waters ×135

* Residue conservation analysis

PDB id:

1f9w

Name:

Contractile protein

Title:

Crystal structures of mutants reveal a signalling pathway for activation of the kinesin motor atpase

Structure:

Kinesin-like protein kar3. Chain: a, b. Fragment: e631a mutant motor domain. Engineered: yes. Mutation: yes

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Expressed in: escherichia coli. Expression_system_taxid: 562. Other_details: saccharomyces cerevisiae

Resolution:

2.50Å R-factor: 0.230 R-free: 0.276

Authors:

M.Yun,X.Zhang,C.G.Park,H.W.Park,S.A.Endow

Key ref:

M.Yun et al. (2001). A structural pathway for activation of the kinesin motor ATPase. EMBO J, 20, 2611-2618. PubMed id: 11387196 DOI: 10.1093/emboj/20.11.2611

Date:

11-Jul-00 Release date: 13-Jun-01

Protein chains

P17119  (KAR3_YEAST) -  Kinesin-like protein KAR3 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 729 a.a.

Struc: 300 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1093/emboj/20.11.2611

EMBO J 20:2611-2618 (2001)

PubMed id: 11387196

A structural pathway for activation of the kinesin motor ATPase.

M.Yun, X.Zhang, C.G.Park, H.W.Park, S.A.Endow.

ABSTRACT

Molecular motors move along actin or microtubules by rapidly hydrolyzing ATP and undergoing changes in filament-binding affinity with steps of the nucleotide hydrolysis cycle. It is generally accepted that motor binding to its filament greatly increases the rate of ATP hydrolysis, but the structural changes in the motor associated with ATPase activation are not known. To identify the conformational changes underlying motor movement on its filament, we solved the crystal structures of three kinesin mutants that decouple nucleotide and microtubule binding by the motor, and block microtubule-activated, but not basal, ATPase activity. Conformational changes in the structures include a disordered loop and helices in the switch I region and a visible switch II loop, which is disordered in wild-type structures. Switch I moved closer to the bound nucleotide in two mutant structures, perturbing water-mediated interactions with the Mg2+. This could weaken Mg2+ binding and accelerate ADP release to activate the motor ATPASE: The structural changes we observe define a signaling pathway within the motor for ATPase activation that is likely to be essential for motor movement on microtubules.

Selected figure(s)

Figure 1.
Figure 1 Wild-type Kar3 and mutated residues. (A) The conserved switch I (SwI, green) and switch II (SwII, cyan) residues are indicated in Kar3+N11 together with helices 3 and 4 (gray). The switch II loop between R632 and the end of helix 4 (dotted line) is disordered and is not present in the model. Residues mutated in the Kar3 N650K uncoupling mutant (gray), Kar3 SwII R632A mutant (gray) and Kar3 salt-bridge mutants (R598A, green; E631A, cyan) are shown space-filled and enlarged in (B). (B) N650 of the Kar3 N650K uncoupling mutant interacts with R632 of SwII in wild-type Kar3. The salt bridge forms between R598 of SwI and E631 of SwII in wild-type Kar3. ADP (black) and Mg2+ (red) are shown as ball-and-stick models. Figure produced using RIBBONS (Carson, 1997).

Figure 5.
Figure 5 Coordination of the Mg2+ ion in wild-type Kar3. The bound Mg2+ of wild-type Kar3 has a tetragonal bipyramidal or octahedral coordination due to the P[ ]oxygen, the hydroxyl group of T481 and four water molecules that also interact with D626 of switch II (cyan), R585 and T587 of loop L9, and N593 of helix 3a. R585 is hydrogen bonded by a water molecule to the D626 side chain that interacts with the Mg2+.

The above figures are reprinted from an Open Access publication published by Macmillan Publishers Ltd: EMBO J (2001, 20, 2611-2618) copyright 2001.

Figures were selected by an automated process.