Molecular role of NAA38 in thermostability and catalytic activity of the human NatC N-terminal acetyltransferase

Sunbin Deng; Sarah M Gardner; Leah Gottlieb; Buyan Pan; E James Petersson; Ronen Marmorstein

doi:10.1016/j.str.2022.12.008

Molecular role of NAA38 in thermostability and catalytic activity of the human NatC N-terminal acetyltransferase

Structure. 2023 Feb 2;31(2):166-173.e4. doi: 10.1016/j.str.2022.12.008. Epub 2023 Jan 12.

Authors

Sunbin Deng¹, Sarah M Gardner², Leah Gottlieb³, Buyan Pan⁴, E James Petersson⁵, Ronen Marmorstein⁶

Affiliations

¹ Department of Chemistry, University of Pennsylvania, 231 South 34(th) Street, Philadelphia, PA 19104, USA; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
² Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA.
³ Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
⁴ Department of Chemistry, University of Pennsylvania, 231 South 34(th) Street, Philadelphia, PA 19104, USA.
⁵ Department of Chemistry, University of Pennsylvania, 231 South 34(th) Street, Philadelphia, PA 19104, USA; Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA.
⁶ Department of Chemistry, University of Pennsylvania, 231 South 34(th) Street, Philadelphia, PA 19104, USA; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA. Electronic address: marmor@upenn.edu.

Abstract

N-terminal acetylation occurs on over 80% of human proteins and is catalyzed by a family of N-terminal acetyltransferases (NATs). All NATs contain a small catalytic subunit, while some also contain a large auxiliary subunit that facilitates catalysis and ribosome targeting for co-translational acetylation. NatC is one of the major NATs containing an NAA30 catalytic subunit, but uniquely contains two auxiliary subunits, large NAA35 and small NAA38. Here, we report the cryo-EM structures of human NatC (hNatC) complexes with and without NAA38, together with biochemical studies, to reveal that NAA38 increases the thermostability and broadens the substrate-specificity profile of NatC by ordering an N-terminal segment of NAA35 and reorienting an NAA30 N-terminal peptide binding loop for optimal catalysis, respectively. We also note important differences in engagement with a stabilizing inositol hexaphosphate molecule between human and yeast NatC. These studies provide new insights for the function and evolution of the NatC complex.

Keywords: N-terminal acetylation; N-terminal acetyltransferase; NATs; NatC; co-translational modification; enzyme mechanism; ribosome.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Acetylation
Amino Acid Sequence
Biocatalysis
Humans
N-Terminal Acetyltransferase C* / metabolism
Ribosomes / metabolism
Saccharomyces cerevisiae / metabolism
Saccharomyces cerevisiae Proteins* / metabolism

Substances

N-Terminal Acetyltransferase C
NAA30 protein, human
Saccharomyces cerevisiae Proteins
NAA38 protein, human

Abstract

Publication types

MeSH terms

Substances

Grants and funding