ISDA: 9ZBP

Deposition Date 2025-11-21

Release Date 2026-01-14

Last Version Date 2026-01-14

Entry Detail

PDB ID:

9ZBP

Keywords:

MOTOR PROTEIN

Title:

Helical Reconstruction of the Complex of Pseudo-Acetylated Human Cardiac Actin (K326/328Q) and Tropomyosin

Biological Source:

Source Organism(s):

Homo sapiens (Taxon ID: 9606)

Expression System(s):

Spodoptera frugiperda, Escherichia coli bl21(de3)

Method Details:

Experimental Method:

ELECTRON MICROSCOPY

Resolution:

3.12 Å

Aggregation State:

FILAMENT

Reconstruction Method:

HELICAL

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Macromolecular Entities

Structures with similar UniProt ID

Protein Blast

Polymer Type:polypeptide(L)
Molecule:Actin, alpha cardiac muscle 1
Gene (Uniprot):ACTC1
Mutagens:K326Q, K328Q
Chain IDs:A, B, C, D, E, F
Chain Length:377
Number of Molecules:6
Biological Source:Homo sapiens

UniProt ID:P68032 Pfam ID:PF00022

Structures with similar UniProt ID

Protein Blast

Polymer Type:polypeptide(L)
Molecule:Tropomyosin alpha-1 chain
Gene (Uniprot):TPM1
Chain IDs:G (auth: M), H (auth: N), I (auth: O), J (auth: P)
Chain Length:286
Number of Molecules:4
Biological Source:Homo sapiens

UniProt ID:P09493 Pfam ID:PF00261

Ligand Molecules

ADP

Primary Citation

Pseudo-acetylation of ACTC1 K326 and K328 promotes dysinhibition of reconstituted human cardiac thin filaments.

Chitre, K, Karpicheva, O.E, King, C.J, Rynkiewicz, M.J, Fenwick, A.J, Dawson, J.F, Foster, D.B, Lehman, W, Cammarato, A.Show

J.Mol.Cell.Cardiol. 212 10 15 (2025)

PMID: 41443503 DOI: 10.1016/j.yjmcc.2025.12.008

Abstact

Electrostatic interactions between actin residues K326 and K328 and tropomyosin bias tropomyosin to an F-actin location where it blocks myosin attachment. K326/328 acetylation neutralizes their charge, potentially disrupting thin filament-based contractile regulation. We verified acetylation of K326/328 on human cardiac actin (ACTC1) and generated recombinant K326/328Q, pseudo-acetylated ACTC1. Pseudo-acetylation reduced inhibition of myosin-driven motility of F-actin-tropomyosin and F-actin-tropomyosin-troponin at low Ca2+. Cryo-EM-based and computational modeling revealed that pseudo-acetylation did not alter tropomyosin positioning along F-actin but decreased local F-actin-tropomyosin interaction energy. Thus, by reducing the energetic demands required for myosin to displace tropomyosin, ACTC1 K326/328 acetylation may promote contractile activation.

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Protein

Chemical

Disease

Primary Citation of related structures

Abstact

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