Back to Search
Start Over
SAC3B is a target of CML19, the centrin 2 of Arabidopsis thaliana
- Publication Year :
- 2020
-
Abstract
- Arabidopsis centrin 2, also known as calmodulin-like protein 19 (CML19), is a member of the EF-hand superfamily of calcium (Ca2+)-binding proteins. In addition to the notion that CML19 interacts with the nucleotide excision repair protein RAD4, CML19 was suggested to be a component of the transcription export complex 2 (TREX-2) by interacting with SAC3B. However, the molecular determinants of this interaction have remained largely unknown. Herein, we identified a CML19-binding site within the C-terminus of SAC3B and characterized the binding properties of the corresponding 26-residue peptide (SAC3Bp), which exhibits the hydrophobic triad centrin-binding motif in a reversed orientation (I8W4W1). Using a combination of spectroscopic and calorimetric experiments, we shed light on the SAC3Bp–CML19 complex structure in solution. We demonstrated that the peptide interacts not only with Ca2+-saturated CML19, but also with apo-CML19 to form a protein–peptide complex with a 1 : 1 stoichiometry. Both interactions involve hydrophobic and electrostatic contributions and include the burial of Trp residues of SAC3Bp. However, the peptide likely assumes different conformations upon binding to apo-CML19 or Ca2+-CML19. Importantly, the peptide dramatically increases the affinity for Ca2+ of CML19, especially of the C-lobe, suggesting that in vivo the protein would be Ca2+-saturated and bound to SAC3B even at resting Ca2+-levels. Our results, providing direct evidence that Arabidopsis SAC3B is a CML19 target and proposing that CML19 can bind to SAC3B through its C-lobe independent of a Ca2+ stimulus, support a functional role for these proteins in TREX-2 complex and mRNA export.
- Subjects :
- Protein Conformation
Direct evidence
Transcription export complex
Arabidopsis
protein–peptide interaction
chemistry.chemical_element
Peptide
Calcium
Biochemistry
TREX-2 complex
03 medical and health sciences
Molecular Biology
030304 developmental biology
chemistry.chemical_classification
0303 health sciences
Messenger RNA
Binding Sites
biology
Arabidopsis Proteins
Chemistry
SAC3B
Calcium-Binding Proteins
030302 biochemistry & molecular biology
Cell Biology
biology.organism_classification
calmodulin-like protein
centrin
Centrin
Biophysics
Carrier Proteins
Protein Binding
Nucleotide excision repair
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....c2df9f285db7c073f1436edbd11ab99c