PMID: 27320834

Authors:

Stove SI, Magin RS, Foyn H, Haug BE, Marmorstein R, Arnesen T

Title:

Crystal Structure of the Golgi-Associated Human Nalpha-Acetyltransferase 60 Reveals the Molecular Determinants for Substrate-Specific Acetylation.

Journal:

Structure. 2016 Jul 6;24(7):1044-56. doi: 10.1016/j.str.2016.04.020. Epub 2016, Jun 16.

Abstract:

N-Terminal acetylation is a common and important protein modification catalyzed by N-terminal acetyltransferases (NATs). Six human NATs (NatA-NatF) contain one catalytic subunit each, Naa10 to Naa60, respectively. In contrast to the ribosome-associated NatA to NatE, NatF/Naa60 specifically associates with Golgi membranes and acetylates transmembrane proteins. To gain insight into the molecular basis for the function of Naa60, we developed an Naa60 bisubstrate CoA-peptide conjugate inhibitor, determined its X-ray structure when bound to CoA and inhibitor, and carried out biochemical experiments. We show that Naa60 adapts an overall fold similar to that of the catalytic subunits of ribosome-associated NATs, but with the addition of two novel elongated loops that play important roles in substrate-specific binding. One of these loops mediates a dimer to monomer transition upon substrate-specific binding. Naa60 employs a catalytic mechanism most similar to Naa50. Collectively, these data reveal the molecular basis for Naa60-specific acetyltransferase activity with implications for its Golgi-specific functions.