PDBsum entry 1n2p

Membrane protein

PDB id: 1n2p

Contents

Protein chain

258 a.a.

Theoretical model

PDB id:

1n2p

Name:

Membrane protein

Title:

In silico-modelled myelin protein zero

Structure:

Myelin protein zero. Chain: a. Synonym: charcot-marie-tooth neuropathy 1b

Source:

Homo sapiens. Human

Authors:

S.C.Mallena,J.A.R.P.Sarma,R.Strausberg

Key ref:

M.Terrak et al. (2005). Structure of the light chain-binding domain of myosin V. Proc Natl Acad Sci U S A, 102, 12718-12723. PubMed id: 16120677 DOI: 10.1073/pnas.0503899102

Date:

24-Oct-02 Release date: 06-Nov-02

Protein chain

No UniProt id for this chain

Struc: 258 a.a.

DOI no: 10.1073/pnas.0503899102

Proc Natl Acad Sci U S A 102:12718-12723 (2005)

PubMed id: 16120677

Structure of the light chain-binding domain of myosin V.

M.Terrak, G.Rebowski, R.C.Lu, Z.Grabarek, R.Dominguez.

ABSTRACT

Myosin V is a double-headed molecular motor involved in organelle transport. Two distinctive features of this motor, processivity and the ability to take extended linear steps of approximately 36 nm along the actin helical track, depend on its unusually long light chain-binding domain (LCBD). The LCBD of myosin V consists of six tandem IQ motifs, which constitute the binding sites for calmodulin (CaM) and CaM-like light chains. Here, we report the 2-A resolution crystal structure of myosin light chain 1 (Mlc1p) bound to the IQ2-IQ3 fragment of Myo2p, a myosin V from Saccharomyces cerevisiae. This structure, combined with FRET distance measurements between probes in various CaM-IQ complexes, comparative sequence analysis, and the previously determined structures of Mlc1p-IQ2 and Mlc1p-IQ4, allowed building a model of the LCBD of myosin V. The IQs of myosin V are distributed into three pairs. There appear to be specific cooperative interactions between light chains within each IQ pair, but little or no interaction between pairs, providing flexibility at their junctions. The second and third IQ pairs each present a light chain, whether CaM or a CaM-related molecule, bound in a noncanonical extended conformation in which the N-lobe does not interact with the IQ motif. The resulting free N-lobes may engage in protein-protein interactions. The extended conformation is characteristic of the single IQ of myosin VI and is common throughout the myosin superfamily. The model points to a prominent role of the LCBD in the function, regulation, and molecular interactions of myosin V.

Selected figure(s)

Figure 1.
Structure of Mlc1p–IQ2,3. (A) Ribbon diagram representation of the structure (N-lobes, blue; C-lobes, red; heavy chain, green). (B) Superimposition of the Mlc1p–IQ2 (gray) and Mlc1p–IQ3 (colored as in A) portions of the structure. The side chain of Tyr-843, which forces the opening of the C-lobe in Mlc1p–IQ3, is shown.

Figure 3.
Model of the LCBD of myosin V. The light chains, which can be either CaM or CaM-related molecules such as Mlc1p are colored cyan (N-lobes) and magenta (C-lobes), and the six-IQ fragment of the heavy chain is colored green. The LCBD of myosin V can be conceptually subdivided into three semiindependent pairs of IQ motifs, with little or no interactions between pairs. The linkers between neighboring IQ pairs are 14 aa long, whereas the linkers between IQs in a pair are 12 aa long. An enlargement illustrates the interaction between light chains in a pair.

Figures were selected by an automated process.