PDBsum entry 3cob

Motor protein

PDB id: 3cob

Contents

Protein chains

355 a.a. *

Ligands

ADP ×2

Metals

_MG ×2

Waters ×215

* Residue conservation analysis

PDB id:

3cob

Name:

Motor protein

Title:

Structural dynamics of the microtubule binding and regulatory elements in the kinesin-like calmodulin binding protein

Structure:

Kinesin heavy chain-like protein. Chain: a, c. Fragment: unp residues 884-1252. Engineered: yes

Source:

Solanum tuberosum. Potato. Expressed in: escherichia coli

Resolution:

2.20Å R-factor: 0.228 R-free: 0.267

Authors:

M.V.Vinogradova,G.G.Malanina,V.Reddy,A.S.N.Reddy,R.J.Fletterick

Key ref:

M.V.Vinogradova et al. (2008). Structural dynamics of the microtubule binding and regulatory elements in the kinesin-like calmodulin binding protein. J Struct Biol, 163, 76-83. PubMed id: 18513992 DOI: 10.1016/j.jsb.2008.04.004

Date:

27-Mar-08 Release date: 24-Jun-08

Protein chains

Q41460  (Q41460_SOLTU) -  Kinesin heavy chain from Solanum tuberosum

Seq: 1265 a.a.

Struc: 355 a.a.

DOI no: 10.1016/j.jsb.2008.04.004

J Struct Biol 163:76-83 (2008)

PubMed id: 18513992

Structural dynamics of the microtubule binding and regulatory elements in the kinesin-like calmodulin binding protein.

M.V.Vinogradova, G.G.Malanina, V.S.Reddy, A.S.Reddy, R.J.Fletterick.

ABSTRACT

Kinesins are molecular motors that power cell division and transport of various proteins and organelles. Their motor activity is driven by ATP hydrolysis and depends on interactions with microtubule tracks. Essential steps in kinesin movement rely on controlled alternate binding to and detaching from the microtubules. The conformational changes in the kinesin motors induced by nucleotide and microtubule binding are coordinated by structural elements within their motor domains. Loop L11 of the kinesin motor domain interacts with the microtubule and is implicated in both microtubule binding and sensing nucleotide bound to the active site of kinesin. Consistent with its proposed role as a microtubule sensor, loop L11 is rarely seen in crystal structures of unattached kinesins. Here, we report four structures of a regulated plant kinesin, the kinesin-like calmodulin binding protein (KCBP), determined by X-ray crystallography. Although all structures reveal the kinesin motor in the ATP-like conformation, its loop L11 is observed in different conformational states, both ordered and disordered. When structured, loop L11 adds three additional helical turns to the N-terminal part of the following helix alpha4. Although interactions with protein neighbors in the crystal support the ordering of loop L11, its observed conformation suggests the conformation for loop L11 in the microtubule-bound kinesin. Variations in the positions of other features of these kinesins were observed. A critical regulatory element of this kinesin, the calmodulin binding helix positioned at the C-terminus of the motor domain, is thought to confer negative regulation of KCBP. Calmodulin binds to this helix and inserts itself between the motor and the microtubule. Comparison of five independent structures of KCBP shows that the positioning of the calmodulin binding helix is not decided by crystal packing forces but is determined by the conformational state of the motor. The observed variations in the position of the calmodulin binding helix fit the regulatory mechanism previously proposed for this kinesin motor.