Role of Post-translational Modifications in Crop Improvement

3.  Proteomics is the study of proteins on
a genome-wide scale.
 Analyze protein features.
 Scope of Proteomics research
 Critical to understand

4.  “Post-translational Modifications is the Chemical
Modification of Protein after its Translation”
OR
 “The Chemical Modification that takes place at certain
amino acids residues after the protein is synthesized by
translation”
 PTMs increases the functional diversity of the proteome by
 Covalent addition of functional groups to proteins
 Proteolytic cleavage of regulatory subunits,
 Degradation of entire proteins,
 Altering protein functions (Stabilizing and localizing) by
binding to amino acids

5.  “Post-translational Modifications is the Chemical
Modification of Protein after its Translation”
OR
 “The Chemical Modification that takes place at certain
amino acids residues after the protein is synthesized by
translation”
 PTMS occur mostly in E.R and golgi apparatus.
 Stability of protein
 Biochemical activity (activity regulation)
 Protein targeting (protein localization)
 Protein signaling (protein-protein interaction)

6. Post-translational modification
Modification Involving Peptide Bonds
Modification of amino acids
Subunit aggregation
Protein folding and chaperones
6
Protein Splicing

7.  These modifications include:
 Phosphorylation
 Glycosylation
 Ubiquitination
 Nitrosylation
 Methylation
 Acetylation
 Lipidation
 Proteolysis
Ref: Google images

8. Influence all aspects of cell biology
Identifying and understanding PTMs is critical in:
Study of cell biology
Disease treatment
Prevention
Crop Improvement
Cell response to stress

9. Can occur at any Step in life Cycle
Tagging of Target Protein
Mono-modification or Poly-modification
Modulation of Stress Related genes
Formation of Transgenic plants over-expressing regulators
of Stress Response
Improves tolerance to single or multiple stress factors.

10.  Metal Stress
 Flooding Stress
 Chill Stress
 Heat Stress
 Water Stress
 Some Biotic Factors
Ref: Google Images

11.  One of Most ordinary Mechanism
 Mediated by “Kinase”
 Reversible protein modification
 It effects following aspects of Protein Function:
 Catalytic activity
 Subcellular localization,
 Stability
 Interaction with other proteins

12.  Phosphorylation depends upon kinase and
phosphatase activities acting on proteins
 Phosphatases are classified by their substrate
preferences as Serine/Threonine, Tyrosine.
 The Serine/Threonine subclass is associated
with low temperature signaling and the
regulation of cold stress response.
 The inhibition of Serine/Threonine
phosphatase activity induces cold-responsive
genes in different species, including
Arabidopsis, alfalfa, potato and tomato.
 PP2A

13.  MAPKs
 CDPKs
 CIPKs
 RLPKs
 ACS6
 ZAT10
 TMT1
 Dehydrins
Ref: Google Images

14. Protein phosphorylation affects
 Metabolism
 The cell cycle,
 Stress,
 Hormonal responses,
 Stomatal closure
 Apoptosis
 Signal transduction pathways.
 Pathogen response, for example, plant–pathogen
interactions, gene expression, and defense signaling in
plants.

15.  Ubiquitin is a small polypeptide
attached to a lysine residue
 Tagging of proteins
 Process
 Action of three enzymes:
 Ubiquitin activating enzyme (E1)
 Ubiquitin conjugating enzyme (E2)
 Ubiquitin ligase (E3).
 26S proteasome, a multisubunit
ATP-dependent protease
Ref: Google Images

16.  1400 genes in the Arabidopsis genome encoding E3
ubiquitin ligases
 Abiotic stresses alter the expression of more than 500
E3-ubiquitin ligase genes,
 ubiquitin-dependent protein degradation in stress-
related signalling and response mechanisms
 Flower buds of Arabidopsis plants carrying a mutation
in the ASK1 gene. In ASK1, the impairment of the SCF
ligase-mediated ubiquitination and the resulting
accumulation of SCF targets allowed the identification
of ubiquitination targets.

17. SUMOylation is another important type of post-translational
modification in which SUMO (Small Ubiquitin-related
Modifier), a small polypeptide very similar to ubiquitin, is
covalently bound to a lysine residue of a target protein.
 Same Enzymes except “SUMO needs to be proteolytically
processed by the Sentrin-specific Protease (SENPs) to
expose the C-terminal”.
 Action of three enzymes:
 SUMO activating enzyme (E1)
 SUMO conjugating enzyme (E2)
 SUMO ligase (E3).

18.  Sumoylation alters protein function
 Biological consequences of sumoylation are:
 Sub-cellular re-localization,
 Changes in enzymatic activity
 Response to environmental signals.
Ref: Google Images

19.  SIZ1 is one of the three E3 SUMO
ligases encoded by the Arabidopsis
genome
 Responsible for augmentation in
SUMO conjugates
 The loss of function causes a
reduction in cold-induced freezing
tolerance.

20.  SUMOylation is involved in:
 Transcriptional regulation,
 DNA repair,
 Nuclear transport,
 Mitochondrial fission
 Regulation of receptors at the plasma
membrane.
 Arabidopsis SIZ1

21. Phosphorylation
Glycosylation
Acylation
Alkylation
Hydroxylation
Pro, Lys Ser, Thr, Tyr
Asn, Ser, Thr
Asn, Gln, Lys
Lys, Arg

22. Glycosylation can be N-linked or O-linked, which is
determined by the transfer of glycosidase and glycosyl
between the Golgi apparatus and the endoplasmic
reticulum.
Proteins at the endomembrane system
N-glycosylation is involved in Stability, Activity and
Subcellular localization of proteins.
The N-glycosylation pattern of 22 rice proteins is
modified, whose Arabidopsis homolog, named LOS2, is
an important regulator of cold acclimation.

23.  Acetylation and deacetylation in N-terminal and K-
residue are suggested as rival to phosphorylation.
 Modify a variety of proteins including:
 Transcription factors,
 Nuclear factors
 Alpha-tubulin
 DNA recognition
 Protein-protein interaction
 Protein stability

24. The transfer of one-carbon methyl group of nitrogen or
oxygen (N- and O-methylation, respectively) to amino
acid side chains increases the hydrophobicity of the
protein and can neutralize a negative amino acid charge
when bound to carboxylic acids.
Methylation is mediated by methyl-transferases, and S-
adenosyl methionine (SAM) is the primary methyl group
donor.

25. Ref: Proteome changes for crop improvement

26. Post-Translational Modifications of Nuclear
Proteins in the Response of Plant Cells to Abiotic
Stresses
REVIEW: Post-translational 1 regulation of cold
acclimation response
Co- and post-translational modifications in
Rubisco
Genomics and Bioinformatics Resources for
Crop Improvement

27. Functional Proteomics of Arabidopsis thaliana
Guard Cells Uncovers New Stomatal Signaling
Pathways
Advances in Proteomics and Bioinformatics in
Agriculture Research and Crop Improvement
Abiotic stress response in plants: When post-
transcriptional and post-translational
regulations control transcription
Proteome changes for crop improvement