6nbe
From Proteopedia
Ternary Complex of Ac-Alpha-Actin with Profilin and CoA-NAA80
Structural highlights
Disease[PROF1_HUMAN] Defects in PFN1 are the cause of amyotrophic lateral sclerosis 18 (ALS18) [MIM:614808]. A neurodegenerative disorder affecting upper motor neurons in the brain and lower motor neurons in the brain stem and spinal cord, resulting in fatal paralysis. Sensory abnormalities are absent. The pathologic hallmarks of the disease include pallor of the corticospinal tract due to loss of motor neurons, presence of ubiquitin-positive inclusions within surviving motor neurons, and deposition of pathologic aggregates. The etiology of amyotrophic lateral sclerosis is likely to be multifactorial, involving both genetic and environmental factors. The disease is inherited in 5-10% of the cases.[1] Function[ACTS_RABIT] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. [PROF1_HUMAN] Binds to actin and affects the structure of the cytoskeleton. At high concentrations, profilin prevents the polymerization of actin, whereas it enhances it at low concentrations. By binding to PIP2, it inhibits the formation of IP3 and DG. Inhibits androgen receptor (AR) and HTT aggregation and binding of G-actin is essential for its inhibition of AR.[2] [NAA80_HUMAN] N-alpha-acetyltransferase that specifically mediates the acetylation of the acidic amino terminus of processed forms of beta- and gamma-actin (ACTB and ACTG, respectively) (PubMed:30028079, PubMed:29581253). N-terminal acetylation of processed beta- and gamma-actin regulates actin filament depolymerization and elongation (PubMed:29581253). In vivo, preferentially displays N-terminal acetyltransferase activity towards acid N-terminal sequences starting with Asp-Asp-Asp and Glu-Glu-Glu (PubMed:30028079, PubMed:29581253). In vitro, shows high activity towards Met-Asp-Glu-Leu and Met-Asp-Asp-Asp (PubMed:10644992, PubMed:29581307). May act as a tumor suppressor (PubMed:10644992).[3] [4] [5] [6] Publication Abstract from PubMedAbout 80% of human proteins are amino-terminally acetylated (Nt-acetylated) by one of seven Nt-acetyltransferases (NATs). Actin, the most abundant protein in the cytoplasm, has its own dedicated NAT, NAA80, which acts posttranslationally and affects cytoskeleton assembly and cell motility. Here, we show that NAA80 does not associate with filamentous actin in cells, and its natural substrate is the monomeric actin-profilin complex, consistent with Nt-acetylation preceding polymerization. NAA80 Nt-acetylates actin-profilin much more efficiently than actin alone, suggesting that profilin acts as a chaperone for actin Nt-acetylation. We determined crystal structures of the NAA80-actin-profilin ternary complex, representing different actin isoforms and different states of the catalytic reaction and revealing the first structure of NAT-substrate complex at atomic resolution. The structural, biochemical, and cellular analysis of mutants shows how NAA80 has evolved to specifically recognize actin among all cellular proteins while targeting all six actin isoforms, which differ the most at the amino terminus. Mechanism of actin N-terminal acetylation.,Rebowski G, Boczkowska M, Drazic A, Ree R, Goris M, Arnesen T, Dominguez R Sci Adv. 2020 Apr 8;6(15):eaay8793. doi: 10.1126/sciadv.aay8793. eCollection 2020, Apr. PMID:32284999[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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