Identification and characterization of the first Nα-acetyltransferase in plastids

ABSTRACT: Protein Nα-terminal acetylation represents one of the most abundant protein modifications of higher eukaryotes. In humans, six Nα-acetyltransferases (Nats) are responsible for the acetylation of approximately 80% of the cytosolic proteins. N-terminal protein acetylation has not been evidenced in organelles of metazoans, but in higher plants, it is a widespread modification not only in the cytosol but also in the chloroplast. In this study, we identify and characterize the first organellar-localized Nat in eukaryotes. A primary sequence-based search in Arabidopsis thaliana revealed seven putatively plastid-localized Nats of which AT2G39000 (AtNAA70) showed the highest conservation of the acetyl-CoA binding pocket. The chloroplastic localization of AtNAA70 was demonstrated by transient expression of AtNAA70:YFP in Arabidopsis mesophyll protoplasts. Homology modeling uncovered a significant conservation of tertiary structural elements between human HsNAA50 and AtNAA70. The in vivo acetylation activity of AtNAA70 was demonstrated on a number of distinct protein N alpha-termini with a newly established Nat-activity global profiling after expression of AtNAA70 in E. coli. AtNAA70 predominately acetylated proteins starting with M, A, S, and T, providing an explanation for most protein N-termini acetylation events found in chloroplasts.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Escherichia Coli

SUBMITTER: Willy Bienvenut  

LAB HEAD: Willy V Bienvenut

PROVIDER: PXD001947 | Pride | 2015-06-29

REPOSITORIES: Pride