Perturbation of the yeast N-acetyltransferase NatB induces elevation of protein phosphorylation levels.

ABSTRACT:

Background

The addition of an acetyl group to protein N-termini is a widespread co-translational modification. NatB is one of the main N-acetyltransferases that targets a subset of proteins possessing an N-terminal methionine, but so far only a handful of substrates have been reported. Using a yeast nat3? strain, deficient for the catalytic subunit of NatB, we employed a quantitative proteomics strategy to identify NatB substrates and to characterize downstream effects in nat3?.

Results

Comparing by proteomics WT and nat3? strains, using metabolic 15N isotope labeling, we confidently identified 59 NatB substrates, out of a total of 756 detected acetylated protein N-termini. We acquired in-depth proteome wide measurements of expression levels of about 2580 proteins. Most remarkably, NatB deletion led to a very significant change in protein phosphorylation.

Conclusions

Protein expression levels change only marginally in between WT and nat3?. A comparison of the detected NatB substrates with their orthologous revealed remarkably little conservation throughout the phylogenetic tree. We further present evidence of post-translational N-acetylation on protein variants at non-annotated N-termini. Moreover, analysis of downstream effects in nat3? revealed elevated protein phosphorylation levels whereby the kinase Snf1p is likely a key element in this process.

SUBMITTER: Helbig AO 

PROVIDER: S-EPMC3091791 | biostudies-literature |

REPOSITORIES: biostudies-literature