9zbl | pdb_00009zbl
Helical Reconstruction of the Human Cardiac F-Actin-Tropomyosin Complex
Structural highlights
DiseaseACTC_HUMAN Atrial septal defect, ostium secundum type;Familial isolated dilated cardiomyopathy;Left ventricular noncompaction;NON RARE IN EUROPE: Familial isolated hypertrophic cardiomyopathy. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. FunctionACTC_HUMAN Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. Publication Abstract from PubMedElectrostatic 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 Ca(2+). 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. Pseudo-acetylation of ACTC1 K326 and K328 promotes dysinhibition of reconstituted human cardiac thin filaments.,Chitre K, Karpicheva OE, King CJ, Rynkiewicz MJ, Fenwick AJ, Dawson JF, Foster DB, Lehman W, Cammarato A J Mol Cell Cardiol. 2025 Dec 22;212:10-15. doi: 10.1016/j.yjmcc.2025.12.008. PMID:41443503[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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