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NAC guides a ribosomal multienzyme complex for nascent protein processing.

Alfred M Lentzsch1, Denis Yudin2, Martin Gamerdinger3

  • 1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.

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|August 21, 2024
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Summary
This summary is machine-generated.

The nascent polypeptide-associated complex (NAC) orchestrates essential protein modifications, methionine excision and acetylation, by assembling enzymes on ribosomes. NAC ensures timely cotranslational processing and activates N-acetyltransferase A (NatA) for efficient protein synthesis.

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Area of Science:

  • Molecular Biology
  • Biochemistry
  • Cell Biology

Background:

  • ~40% of mammalian proteins undergo N-terminal methionine excision and acetylation.
  • These modifications are cotranslational and essential in eukaryotes.
  • Enzyme interactions and regulation during translation remain unclear.

Purpose of the Study:

  • To elucidate the role of the nascent polypeptide-associated complex (NAC) in cotranslational protein modification.
  • To investigate how NAC interacts with methionine aminopeptidase (MetAP) and N-acetyltransferase A (NatA).
  • To understand the regulation of NatA activity by NAC and huntingtin yeast two-hybrid protein K (HYPK).

Main Methods:

  • Biochemical assays
  • Structural biology studies
  • In vivo experiments

Main Results:

  • NAC forms a multienzyme complex with MetAP1 and NatA on translating ribosomes.
  • NAC positions MetAP1 and NatA for sequential processing of nascent proteins.
  • NAC releases HYPK inhibition to activate NatA, ensuring cotranslational acetylation.

Conclusions:

  • NAC acts as a scaffold to orchestrate cotranslational N-terminal methionine excision and acetylation.
  • A mechanistic model for ribosome-associated protein processing is proposed.
  • NAC is crucial for efficient and accurate cotranslational protein modification in eukaryotes.