Publication Information
Willems et al., 2021
Abstract
Front Plant Sci. 2022 Jan 6;12:778804. doi: 10.3389/fpls.2021.778804.
eCollection 2021.
To New Beginnings: Riboproteogenomics Discovery of N-Terminal Proteoforms in
Arabidopsis Thaliana.
Willems P(1)(2), Ndah E(3), Jonckheere V(3), Van Breusegem F(1)(2), Van Damme
P(3).
Author information:
(1)Department of Plant Biotechnology and Bioinformatics, Ghent University,
Ghent, Belgium.
(2)Vlaams Instituut voor Biotechnologie (VIB)-Center for Plant Systems Biology,
Ghent, Belgium.
(3)integrative Riboproteogenomics, Interactomics and Proteomics Unit, Laboratory
of Microbiology, Department of Biochemistry and Microbiology, Ghent University,
Ghent, Belgium.
Alternative translation initiation is a widespread event in biology that can
shape multiple protein forms or proteoforms from a single gene. However, the
respective contribution of alternative translation to protein complexity remains
largely enigmatic. By complementary ribosome profiling and N-terminal proteomics
(i.e., riboproteogenomics), we provide clear-cut evidence for ~90 N-terminal
proteoform pairs shaped by (alternative) translation initiation in Arabidopsis
thaliana. Next to several cases additionally confirmed by directed mutagenesis,
identified alternative protein N-termini follow the enzymatic rules of
co-translational N-terminal protein acetylation and initiator methionine
removal. In contrast to other eukaryotic models, N-terminal acetylation in
plants cannot generally be considered as a proxy of translation initiation
because of its posttranslational occurrence on mature proteolytic neo-termini
(N-termini) localized in the chloroplast stroma. Quantification of N-terminal
acetylation revealed differing co- vs. posttranslational N-terminal acetylation
patterns. Intriguingly, our data additionally hints to alternative translation
initiation serving as a common mechanism to supply protein copies in multiple
cellular compartments, as alternative translation sites are often in close
proximity to cleavage sites of N-terminal transit sequences of nuclear-encoded
chloroplastic and mitochondrial proteins. Overall, riboproteogenomics screening
enables the identification of (differential localized) N-terminal proteoforms
raised upon alternative translation.
Copyright © 2022 Willems, Ndah, Jonckheere, Van Breusegem and Van Damme.
DOI: 10.3389/fpls.2021.778804
PMCID: PMC8770321
PMID: 35069635
Conflict of interest statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
