Acetylome Analysis Reveals
the Involvement of Lysine Acetylation in Photosynthesis and Carbon
Metabolism in the Model Cyanobacterium Synechocystis sp. PCC 6803
Cyanobacteria
are the oldest known life form inhabiting Earth and the only prokaryotes
capable of performing oxygenic photosynthesis. Synechocystis sp. PCC 6803 (Synechocystis) is a model cyanobacterium
used extensively in research on photosynthesis and environmental adaptation.
Posttranslational protein modification by lysine acetylation plays
a critical regulatory role in both eukaryotes and prokaryotes; however,
its extent and function in cyanobacteria remain unexplored. Herein,
we performed a global acetylome analysis on Synechocystis through peptide prefractionation, antibody enrichment, and high
accuracy LC–MS/MS analysis; identified 776 acetylation sites
on 513 acetylated proteins; and functionally categorized them into
an interaction map showing their involvement in various biological
processes. Consistent with previous reports, a large fraction of the
acetylation sites are present on proteins involved in cellular metabolism.
Interestingly, for the first time, many proteins involved in photosynthesis,
including the subunits of phycocyanin (CpcA, CpcB, CpcC, and CpcG)
and allophycocyanin (ApcA, ApcB, ApcD, ApcE, and ApcF), were found
to be lysine acetylated, suggesting that lysine acetylation may play
regulatory roles in the photosynthesis process. Six identified acetylated
proteins associated with photosynthesis and carbon metabolism were
further validated by immunoprecipitation and Western blotting. Our
data provide the first global survey of lysine acetylation in cyanobacteria
and reveal previously unappreciated roles of lysine acetylation in
the regulation of photosynthesis. The provided data set may serve
as an important resource for the functional analysis of lysine acetylation
in cyanobacteria and facilitate the elucidation of the entire metabolic
networks and photosynthesis process in this model cyanobacterium.