Crystal Structure of the Golgi-Associated Human Nα-Acetyltransferase 60 Reveals the Molecular Determinants for Substrate-Specific Acetylation.
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.
Department of Molecular Biology, University of Bergen, 5020 Bergen, Norway; Department of Surgery, Haukeland University Hospital, 5021 Bergen, Norway.
Svein Isungset
SI
Støve
Department of Biochemistry and Biophysics, Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Program in Gene Expression and Regulation, Wistar Institute, Philadelphia, PA 19104, USA.
Robert S
RS
Magin
Department of Molecular Biology, University of Bergen, 5020 Bergen, Norway.
Håvard
H
Foyn
Department of Chemistry, University of Bergen, 5020 Bergen, Norway.
Bengt Erik
BE
Haug
Department of Biochemistry and Biophysics, Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Program in Gene Expression and Regulation, Wistar Institute, Philadelphia, PA 19104, USA. Electronic address: marmor@mail.med.upenn.edu.
Ronen
R
Marmorstein
Department of Molecular Biology, University of Bergen, 5020 Bergen, Norway; Department of Surgery, Haukeland University Hospital, 5021 Bergen, Norway. Electronic address: thomas.arnesen@uib.no.
Thomas
T
Arnesen
D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D063214:N-Terminal Acetyltransferase F / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding
C570958:NAA60 protein, human; D063214:N-Terminal Acetyltransferase F
N-terminal acetylation; NAT; Naa60; NatF; acetyltransferase; crystal structure