AI Article Synopsis

  • Nα-acetylation is a modification of proteins' N-termini driven by Nα-acetyltransferases (NATs), which are less understood in bacteria compared to eukaryotes, where they are categorized into six types based on specific functions.
  • Despite the variety, bacterial NATs like RimI(Mtb) from Mycobacterium tuberculosis show significant differences from eukaryotic NATs, with RimI(Mtb) demonstrating a broader substrate range similar to several eukaryotic types.
  • The study identifies RimI(Mtb) as capable of acetylating previously unknown residues (Asp, Glu, Tyr, and Leu) in vitro, providing insights into its potential cellular substrates.

Article Abstract

Nα-acetylation is a naturally occurring irreversible modification of N-termini of proteins catalyzed by Nα-acetyltransferases (NATs). Although present in all three domains of life, it is little understood in bacteria. The functional grouping of NATs into six types NatA - NatF, in eukaryotes is based on subunit requirements and stringent substrate specificities. Bacterial orthologs are phylogenetically divergent from eukaryotic NATs, and only a couple of them are characterized biochemically. Accordingly, not much is known about their substrate specificities. Rv3420c of Mycobacterium tuberculosis is a NAT ortholog coding for RimI(Mtb). Using in vitro peptide-based enzyme assays and mass-spectrometry methods, we provide evidence that RimI(Mtb) is a protein Nα-acetyltransferase of relaxed substrate specificity mimicking substrate specificities of eukaryotic NatA, NatC and most competently that of NatE. Also, hitherto unknown acetylation of residues namely, Asp, Glu, Tyr and Leu by a bacterial NAT (RimI(Mtb)) is elucidated, in vitro. Based on in vivo acetylation status, in vitro assay results and genetic context, a plausible cellular substrate for RimI(Mtb) is proposed.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4926160PMC
http://dx.doi.org/10.1038/srep28892DOI Listing

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