0 avis
The plastidial protein acetyltransferase GNAT1 forms a complex with GNAT2, yet their interaction is dispensable for state transitions
Archive ouverte
Edité par CCSD ; American Society for Biochemistry and Molecular Biology -
International audience. Protein N-acetylation is one of the most abundant co- and post-translational modifications ineukaryotes, extending its occurrence to chloroplasts within vascular plants. Recently, a novelplastidial enzyme family comprising eight acetyltransferases that exhibit dual lysine and Nterminusacetylation activities was unveiled in Arabidopsis. Among these, GNAT1, GNAT2, andGNAT3 reveal notable phylogenetic proximity, forming a subgroup termed NAA90. Our studyfocused on characterizing GNAT1, closely related to the state transition acetyltransferase GNAT2.In contrast to GNAT2, GNAT1 did not prove essential for state transitions and displayed nodiscernible phenotypic difference compared to the wild type under high light conditions, whilegnat2 mutants were severely affected. However, gnat1 mutants exhibited a tighter packing of thethylakoid membranes akin to gnat2 mutants. In vitro studies with recombinant GNAT1demonstrated robust N-terminus acetylation activity on synthetic substrate peptides. This activitywas confirmed in vivo through N-terminal acetylome profiling in two independent gnat1 knockoutlines. This attributed several acetylation sites on plastidial proteins to GNAT1, reflecting a subsetof GNAT2’s substrate spectrum. Moreover, co-immunoprecipitation coupled to mass spectrometryrevealed a robust interaction between GNAT1 and GNAT2, as well as a significant association ofGNAT2 with GNAT3 - the third acetyltransferase within the NAA90 subfamily. This study unveilsthe existence of at least two acetyltransferase complexes within chloroplasts, whereby complexformation might have a critical effect on the fine-tuning of the overall acetyltransferase activities.These findings introduce a novel layer of regulation in acetylation-dependent adjustments inplastidial metabolism.
Consulter en ligne
Suggestions
Du même auteur
