Sulfolobus islandicus top-down LC-MSMS

ABSTRACT: Protein posttranslational methylation and acetylations have been reported to occur in archaea, including members of the genus Sulfolobus, but have not been characterized on a proteome-wide scale. Sulfolobus chromatin proteins are known to be methylated and acetylated on lysine side chains, resembling eukaryotic histones in this respect. We utilized bottom-up and top-down proteomic approaches to perform a global and deep methylation study in the hyperthermoacidophylic archaeon S. islandicus with particular interest in chromatin proteins. Without specific enrichment, 731 protein were found by bottom-up proteomic analysis. The methylation sites on >400 proteins were monitored throughout 3 cell culture growth stages: early exponential, late exponential and stationary. (The previously described aKMT4 is found to be a plausible methyltransferase responsible for the massive methylation.) The proteome-wide top-down study/approach revealed 3778 proteoforms of 681 proteins, including 292 methylated proteoforms, of which 85 were comprehensively characterized by high-resolution MS/MS. Methylated proteoforms of the five chromatin proteins were characterized in detail by combination of bottom-up and top-down data showing the differences between the closely related Sul7d proteins. The two Alba chromatin proteins are, for the first time, reported to be methylated in this work. Alba1 protein is shown to be mono-, di- and trimethylated at the lysine-16 side chain. Stage-wise top-down analysis shows that the relative abundance of the methylated proteoforms versus non-methylated ones significantly grows/increases for Alba1 and Cren7 chromatin proteins throughout the cell growth. These findings highlight the ubiquitous lysine methylation throughout the S. islandicus proteome and singificantly enrich our knowledge related aboutarchaeal chromatin proteins.

INSTRUMENT(S): Orbitrap Fusion ETD

ORGANISM(S): Sulfolobus Islandicus Lal14/1

SUBMITTER: Egor Vorontsov  

LAB HEAD: Julia Chamot-Rooke

PROVIDER: PXD003074 | Pride | 2016-09-13

REPOSITORIES: Pride