PDBsum entry 7k20

Cytosolic protein

PDB id: 7k20

Contents

Protein chains

372 a.a.

Ligands

ADP ×4

1T4 ×4

Metals

_MG ×4

PDB id:

7k20

Name:

Cytosolic protein

Title:

Cryo-em structure of pyrene-labeled adp-actin filaments

Structure:

Actin, alpha skeletal muscle. Chain: a, b, c, d. Synonym: alpha-actin-1. Other_details: the c19 atom of pyrene (1t4) is chemically conjugated to the sg atom of actin c374

Source:

Gallus gallus. Chicken. Organism_taxid: 9031

Authors:

S.Z.Chou,T.D.Pollard

Key ref:

S.Z.Chou and T.D.Pollard (2020). Cryo-electron microscopy structures of pyrene-labeled ADP-P_i- and ADP-actin filaments. Nat Commun, 11, 5897. PubMed id: 33214556 DOI: 10.1038/s41467-020-19762-1

Date:

08-Sep-20 Release date: 04-Nov-20

Protein chains

P68139  (ACTS_CHICK) -  Actin, alpha skeletal muscle from Gallus gallus

Seq: 377 a.a.

Struc: 372 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.3.6.4.- - ?????

DOI no: 10.1038/s41467-020-19762-1

Nat Commun 11:5897 (2020)

PubMed id: 33214556

Cryo-electron microscopy structures of pyrene-labeled ADP-P_i- and ADP-actin filaments.

S.Z.Chou, T.D.Pollard.

ABSTRACT

Since the fluorescent reagent N-(1-pyrene)iodoacetamide was first used to label skeletal muscle actin in 1981, the pyrene-labeled actin has become the most widely employed tool to measure the kinetics of actin polymerization and the interaction between actin and actin-binding proteins. Here we report high-resolution cryo-electron microscopy structures of actin filaments with N-1-pyrene conjugated to cysteine 374 and either ADP (3.2 Å) or ADP-phosphate (3.0 Å) in the active site. Polymerization buries pyrene in a hydrophobic cavity between subunits along the long-pitch helix with only minor differences in conformation compared with native actin filaments. These structures explain how polymerization increases the fluorescence 20-fold, how myosin and cofilin binding to filaments reduces the fluorescence, and how profilin binding to actin monomers increases the fluorescence.