PDBsum entry 2os8

Contractile protein

PDB id: 2os8

Contents

Protein chains

798 a.a. *

135 a.a. *

155 a.a. *

Metals

_MG

_CA

* Residue conservation analysis

PDB id:

2os8

Name:

Contractile protein

Title:

Rigor-like structures of muscle myosins reveal key mechanical elements in the transduction pathways of this allosteric motor

Structure:

Myosin heavy chain. Chain: a. Fragment: myosin heavy chain. Myosin regulatory light chain. Chain: b. Fragment: myosin rlc. Myosin essential light chain. Chain: c. Fragment: myosin elc

Source:

Placopecten magellanicus. Sea scallop. Organism_taxid: 6577. Organism_taxid: 6577

Resolution:

3.27Å R-factor: 0.281 R-free: 0.314

Authors:

Y.Yang,S.Gourinath,C.Cohen,J.H.Brown

Key ref:

Y.Yang et al. (2007). Rigor-like Structures from Muscle Myosins Reveal Key Mechanical Elements in the Transduction Pathways of This Allosteric Motor. Structure, 15, 553-564. PubMed id: 17502101 DOI: 10.1016/j.str.2007.03.010

Date:

05-Feb-07 Release date: 29-May-07

Protein chain

Q26080  (Q26080_PLAMG) -  Myosin heavy chain from Placopecten magellanicus

Seq: 1950 a.a.

Struc: 798 a.a.

Protein chain

Q26068  (Q26068_PLAMG) -  Myosin regulatory light chain from Placopecten magellanicus

Seq: 157 a.a.

Struc: 135 a.a.

Protein chain

Q26066  (Q26066_PLAMG) -  Myosin essential light chain from Placopecten magellanicus

Seq: 157 a.a.

Struc: 155 a.a.

DOI no: 10.1016/j.str.2007.03.010

Structure 15:553-564 (2007)

PubMed id: 17502101

Rigor-like Structures from Muscle Myosins Reveal Key Mechanical Elements in the Transduction Pathways of This Allosteric Motor.

Y.Yang, S.Gourinath, M.Kovács, L.Nyitray, R.Reutzel, D.M.Himmel, E.O'neall-Hennessey, L.Reshetnikova, A.G.Szent-Györgyi, J.H.Brown, C.Cohen.

ABSTRACT

Unlike processive cellular motors such as myosin V, whose structure has recently been determined in a "rigor-like" conformation, myosin II from contracting muscle filaments necessarily spends most of its time detached from actin. By using squid and sea scallop sources, however, we have now obtained similar rigor-like atomic structures for muscle myosin heads (S1). The significance of the hallmark closed actin-binding cleft in these crystal structures is supported here by actin/S1-binding studies. These structures reveal how different duty ratios, and hence cellular functions, of the myosin isoforms may be accounted for, in part, on the basis of detailed differences in interdomain contacts. Moreover, the rigor-like position of switch II turns out to be unique for myosin V. The overall arrangements of subdomains in the motor are relatively conserved in each of the known contractile states, and we explore qualitatively the energetics of these states.

Selected figure(s)

Figure 2.
Figure 2. Comparison of the Rigor-like and Post-Rigor States of Muscle Myosin S1 and Its Active Site
(A and B) Detailed legends for all figures are supplied in Supplemental Data. (A) Schematic overlay of (squid) S1 in the two states (see text). The rigor-like state is shown in green, and the post-rigor state is shown in red. Thicker lines indicate proximity to the reader. The overall conformational differences between these (and the pre-power stroke) states are generally conserved in the different isoforms. The locations of interdomain interactions that nevertheless appear to preferentially stabilize the high-duty ratio non-muscle myosin V in a rigor-like conformation and some of the low-duty ratio myosin II isoforms in a non-rigor-like (actin-detached) conformation are indicated here with blue and red asterisks, respectively (also see text and Figure 3, Figure 4 and Figure 5). (B) The rigor-like location of switch II in the various myosin II and VI structures (green), which have small side chains at (squid) position 465, differs from that in myosin V (blue), in which 465 is a tyrosine. The locations of both switch I and switch II away from the nucleotide and near each other force the tyrosine to adopt a “g−” rotamer. The myosin V switch II is displaced toward the P loop of the N-terminal subdomain in the rigor-like state to avoid a clash of this rotamer with helix W (not shown). In the post-rigor state (red), switch I (including Ser246) is near the nucleotide and relatively far from switch II. Here, the tyrosine has room to adopt the “g+” rotamer and does not perturb the arrangement of the active site elements.

Figure 3.
Figure 3. Conserved and Variable Features of the Rigor-like 50 kDa Cleft
(A–E) The schematic S1 inset on this and subsequent figures shows the region that is magnified (box) and the viewpoint (arrow). Squid sequence numbering is used. (A) Displayed are selected interactions between the upper (dark green) and lower (light green) 50 kDa subdomains made in the squid rigor-like structure that are also made (with identical or homologous residues) in the other isoforms studied when the corresponding part of their cleft is also fully closed. Interactions include H-bonded/electrostatic contacts (dotted lines) and extensive burial of certain apolar residues (underlined labels). (B–E) Variations in crosscleft contacts, as well as in the orientations of the upper and lower 50 kDa subdomains or of subregions within them, help determine the extent of inner and outer cleft closure in the various isoforms (the green, dashed line shows squid for comparison.) (B) Myosin V displays the most closed cleft in the strut region (also see Table 1), perhaps due to a “complex H-bond link” (blue, dotted lines) between Asn424, Lys601, and Glu598 not seen in any other isoform; position 598 is aspartate in squid and sea scallop, and 424 is serine in Dictyostelium (see below for myosin VI). (C) A slightly modified orientation of helix HR relative to helix HQ yields a fully closed outer but incompletely closed inner cleft in catch and striated sea scallop S1. (D) Curvature of helix HO about a Dictyostelium-specific glycine at 435 contributes to its fully closed inner but partially open outer cleft. (E) The entire cleft of myosin VI is incompletely closed. A myosin VI-specific lysine at position 650 appears to disrupt the interdomain 602-274-431 complex salt link made from the strut.

The above figures are reprinted by permission from Cell Press: Structure (2007, 15, 553-564) copyright 2007.

Figures were selected by an automated process.