PDBsum entry 4pkg

Contractile protein/actin-binding protei

PDB id: 4pkg

Contents

Protein chains

371 a.a.

168 a.a.

Ligands

ATP

Metals

_CA ×3

Waters ×511

PDB id:

4pkg

Name:

Contractile protein/actin-binding protei

Title:

Complex of atp-actin with the n-terminal actin-binding domain of tropomodulin

Structure:

Actin, alpha skeletal muscle. Chain: a. Synonym: alpha-actin-1. Gelsolin,tropomodulin-1 chimera. Chain: g. Fragment: gelsolin (unp residues 12-136), ggsggsggs linker, tmod1 actin-binding site 1 (unp residues 50-101). Synonym: agel,actin-depolymerizing factor,adf,brevin,erythrocyte tropomodulin,e-tmod.

Source:

Oryctolagus cuniculus. Rabbit. Organism_taxid: 9986. Tissue: skeletal muscle. Homo sapiens. Human. Organism_taxid: 9606. Gene: gsn, tmod1, d9s57e, tmod. Expressed in: escherichia coli.

Resolution:

1.80Å R-factor: 0.157 R-free: 0.187

Authors:

J.N.Rao,R.Dominguez

Key ref:

J.N.Rao et al. (2014). Mechanism of actin filament pointed-end capping by tropomodulin. Science, 345, 463-467. PubMed id: 25061212 DOI: 10.1126/science.1256159

Date:

14-May-14 Release date: 30-Jul-14

Protein chain

P68135  (ACTS_RABIT) -  Actin, alpha skeletal muscle from Oryctolagus cuniculus

Seq: 377 a.a.

Struc: 371 a.a.*

Protein chain

P06396  (GELS_HUMAN) -  Gelsolin from Homo sapiens

Seq: 782 a.a.

Struc: 168 a.a.*

Protein chain

P28289  (TMOD1_HUMAN) -  Tropomodulin-1 from Homo sapiens

Seq: 359 a.a.

Struc: 168 a.a.*

* PDB and UniProt seqs differ at 93 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chain A: E.C.3.6.4.- - ?????

DOI no: 10.1126/science.1256159

Science 345:463-467 (2014)

PubMed id: 25061212

Mechanism of actin filament pointed-end capping by tropomodulin.

J.N.Rao, Y.Madasu, R.Dominguez.

ABSTRACT

Proteins that cap the ends of the actin filament are essential regulators of cytoskeleton dynamics. Whereas several proteins cap the rapidly growing barbed end, tropomodulin (Tmod) is the only protein known to cap the slowly growing pointed end. The lack of structural information severely limits our understanding of Tmod's capping mechanism. We describe crystal structures of actin complexes with the unstructured amino-terminal and the leucine-rich repeat carboxy-terminal domains of Tmod. The structures and biochemical analysis of structure-inspired mutants showed that one Tmod molecule interacts with three actin subunits at the pointed end, while also contacting two tropomyosin molecules on each side of the filament. We found that Tmod achieves high-affinity binding through several discrete low-affinity interactions, which suggests a mechanism for controlled subunit exchange at the pointed end.