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Signal transduction in plants
b
Post-translational modifications
(PTMS)
Michael Wrzaczek
Dept of Biosciences, Plant Biology
Viikki Plant Science Centre (ViPS)
University of Helsinki, Finland
Helsinki, August 18th, 2016
Post-translational modification (PTM) refers
to the covalent and generally enzymatic
modification of proteins during or after
protein biosynthesis.
(source: www.wikipedia.org)
PTMs are diverse
Lipids
Carbohydrates
Degradation
Protein/peptide
processing
Wang (2014) Cell Res 24: 143-160
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Plants possess more than 300 PTMs
Phosphorylation is arguably the most widely studied PTM
Serine (S)
Phosphoserine (pS)
Lecture by Julia Krasensky, Friday August 19
PTMs can be reversible or irreversible
e.g.
• Phosphorylation
• PARylation
• Ubiquitination
• Acetylation
e.g.
• Degradation
• Cleavage
• Some forms of
protein methylation
Friso & van Wijk (2016) Plant Physiol 169: 1469-1487
Many – but not all – PTMs
are attached enzymatically
Enzyme
Mod
Substrate
protein
Substrate
protein
’Reverse enzyme’
Friso & van Wijk (2016) Plant Physiol 169: 1469-1487
What do PTMs do?
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Increase proteome diversity
Increase functionality
Allow for rapid responses
Relatively low cost for the cell
PTMs increase proteome complexity
What do PTMs do?
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Charge
Structure
Localization
Interaction
Information processing
Jensen (2006) Nature Rev Mol Cell Biol 7: 391-403
What do PTMs do?
Hydrophobic groups for membrane localization
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myristoylation
palmitoylation
isoprenylation or prenylation (farnesylation, geranylgeranylation)
GPI anchor formation
What do PTMs do?
Jensen (2006) Nature Rev Mol Cell Biol 7: 391-403
Writer: an enzyme that is responsible
for adding a posttranslational
modification(s) into a given protein
(e.g., HKMT)
Reader: a protein or protein complex
that recognizes and binds specifically
to a particular posttranslationally
modified substrate
Eraser: an enzyme that removes a
Posttranslational modification(s) from
a given protein (e.g., HDM)
Liu et al. (2010) Annu Rev Plant Biol 61: 395-420
PTMs for cellular ‚information processing‘
• Information processing
Prakakaran et al. (2012) WIREs Syst Biol Med doi: 10.1002/wsbm.1185
Liu et al. (2010) Annu Rev Plant Biol 61: 395-420
How to detect PTMs?
How do you know your
protein is carrying a PTM?
Buehl et al. (2014) BioTechniques 57: 72-80
Goldknopf & Busch (1977) PNAS 74: 864-868
Antibodies for detecting a PTM
+
NAD
PARP
ADP-ribose
acceptor
protein
acceptor
protein
Poly (ADP-ribose)
PARG
n
Vainonen et al. 2016. Manuscript in preparation
Proteomic detection of PTMs
Ytterberg & Jensen (2010) J Proteomics 73: 2249-2266
Ytterberg & Jensen (2010) J Proteomics 73: 2249-2266
Ytterberg & Jensen (2010) J Proteomics 73: 2249-2266
Summary: there are many PTMs
Summary: PTMs have many roles
PTMs add complexity to proteomes
and allow fast responses
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Charge
Structure
Localization
Interaction
Information processing
Summary: PTMs have many roles
Jensen (2006) Nature Rev Mol Cell Biol 7: 391-403