Molecular basis for N-terminal alpha-synuclein acetylation by human NatB

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• N-terminal acetyltransferases (NATs) modify proteins co-translationally.
• The NatB complex acetylates approximately 21% of human proteins, including alpha-synuclein (αSyn).
• N-terminal acetylation of αSyn by human NatB (hNatB) is implicated in Parkinson's disease and hepatocellular carcinoma.

Purpose of the Study:

• To determine the cryo-electron microscopy (cryo-EM) structure of the hNatB complex bound to a CoA-αSyn conjugate.
• To analyze structure-guided mutations affecting hNatB catalysis and substrate recognition.
• To elucidate the molecular mechanisms underlying hNatB-mediated αSyn N-terminal acetylation.

Main Methods:

• Cryo-electron microscopy (cryo-EM) for structural determination.
• Site-directed mutagenesis to assess catalytic activity.
• Biochemical assays to analyze enzyme kinetics and substrate specificity.

Main Results:

• The cryo-EM structure of hNatB bound to CoA-αSyn was resolved.
• Key hNatB protein determinants for αSyn N-terminal acetylation were identified.
• Functional differences between hNatB and other NAT complexes (hNatA, CaNatB) were revealed.
• Important residues for substrate recognition and acetylation by NatB enzymes were pinpointed.

Conclusions:

• The structural and mutational analyses provide critical insights into hNatB function.
• Understanding hNatB-αSyn interactions has implications for Parkinson's disease pathogenesis.
• Findings support the development of small molecule probes targeting hNatB for therapeutic intervention.
• This study advances the understanding of substrate selection mechanisms in NAT enzymes.