PDBsum entry 3bas

Contractile protein

PDB id: 3bas

Contents

Protein chains

80 a.a. *

87 a.a. *

Metals

IOD

Waters ×59

* Residue conservation analysis

PDB id:

3bas

Name:

Contractile protein

Title:

Crystal structure of the n-terminal region of the scallop myosin rod, monoclinic (c2) form

Structure:

Myosin heavy chain, striated muscle/general control protein gcn4 chimera. Chain: a, b. Fragment: bay scallop myosin (residues 835-885)/yeast gcn4 transcription factor (residues 250-281). Synonym: -/amino acid biosynthesis regulatory protein. Engineered: yes

Source:

Argopecten irradians, saccharomyces cerevisiae. , Baker's yeast. Organism_taxid: 31199, 4932. Strain: ,. Tissue: adductor muscle/-. Gene: -/gcn4, aas3, arg9, yel009c. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.30Å R-factor: 0.246 R-free: 0.287

Authors:

J.H.Brown,C.Cohen

Key ref:

J.H.Brown et al. (2008). An unstable head-rod junction may promote folding into the compact off-state conformation of regulated myosins. J Mol Biol, 375, 1434-1443. PubMed id: 18155233 DOI: 10.1016/j.jmb.2007.11.071

Date:

08-Nov-07 Release date: 08-Jan-08

Protein chain

P03069  (GCN4_YEAST) -  General control transcription factor GCN4 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 281 a.a.

Struc: 80 a.a.*

Protein chain

P24733  (MYS_ARGIR) -  Myosin heavy chain, striated muscle from Argopecten irradians

Seq: 1938 a.a.

Struc: 80 a.a.*

Protein chain

P03069  (GCN4_YEAST) -  General control transcription factor GCN4 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 281 a.a.

Struc: 87 a.a.*

Protein chain

P24733  (MYS_ARGIR) -  Myosin heavy chain, striated muscle from Argopecten irradians

Seq: 1938 a.a.

Struc: 87 a.a.*

* PDB and UniProt seqs differ at 154 residue positions (black crosses)

DOI no: 10.1016/j.jmb.2007.11.071

J Mol Biol 375:1434-1443 (2008)

PubMed id: 18155233

An unstable head-rod junction may promote folding into the compact off-state conformation of regulated myosins.

J.H.Brown, Y.Yang, L.Reshetnikova, S.Gourinath, D.Süveges, J.Kardos, F.Hóbor, R.Reutzel, L.Nyitray, C.Cohen.

ABSTRACT

The N-terminal region of myosin's rod-like subfragment 2 (S2) joins the two heads of this dimeric molecule and is key to its function. Previously, a crystal structure of this predominantly coiled-coil region was determined for a short fragment (51 residues plus a leucine zipper) of the scallop striated muscle myosin isoform. In that study, the N-terminal 10-14 residues were found to be disordered. We have now determined the structure of the same scallop peptide in three additional crystal environments. In each of two of these structures, improved order has allowed visualization of the entire N-terminus in one chain of the dimeric peptide. We have also compared the melting temperatures of this scallop S2 peptide with those of analogous peptides from three other isoforms. Taken together, these experiments, along with examination of sequences, point to a diminished stability of the N-terminal region of S2 in regulated myosins, compared with those myosins whose regulation is thin filament linked. It seems plain that this isoform-specific instability promotes the off-state conformation of the heads in regulated myosins. We also discuss how myosin isoforms with varied thermal stabilities share the basic capacity to transmit force efficiently in order to produce contraction in their on states.

Selected figure(s)

Figure 1.
Fig. 1. Overview of the S2N51 structure and its critical location in the myosin II dimer. (a) Schematic diagram of myosin II in an on-state conformation. (b) Schematic diagram of an expanded view of the construct crystallized in the present study. (c) Ribbon diagram of the best-ordered structure of S2N51, crystallized in the monoclinic C2 space group. Gray indicates C-terminally attached GCN4 leucine zipper and N-terminally attached tetrapeptide tag. S2N51 is colored by temperature factor (see Fig. 2). The box indicates the region immediately adjacent to the head–rod junction and is described in more detail in Fig. 2 and Fig. 3. (d) Schematic diagram of the off-state conformation of regulated myosin II (adapted from Ref. 3).

Figure 4.
Fig. 4. Diminished axial-stagger asymmetry in the N-terminal region of scallop S2 (red solid lines) relative to human cardiac S2 (blue dashed lines). Axial staggering may therefore not be a general inducer of nonequivalence of S1 heads in off-state structures of myosin (see Discussion). The difference between these isoforms in the axial staggering between the helices is most extensive for those structures (darkest shades) with the highest order nearest the N-terminus. Stagger at any residue is calculated from output of LSQAB^28 from the CCP4 program suite,^29 in which 7-residue-long segments of the two helices of a coiled coil are fitted. The axial staggers are calculated for the N-terminal regions of five crystallographically independent scallop S2 coiled coils (from the C2 space group and the two coiled coils from each of the P2[1]2[1]2[1] and P2[1] space groups) and of three crystallographically independent human cardiac S2 coiled coils (one wild type and two coiled coils in which a residue outside the measured region was mutated) (see Ref. 21).

The above figures are reprinted from an Open Access publication published by Elsevier: J Mol Biol (2008, 375, 1434-1443) copyright 2008.

Figures were selected by an automated process.