Objectives: Due to the complexity of DNA-Repair Mechanisms in Plants, this work will
give more insights to better understanding the dark DNA-repair mechanism through the interactome
analysis of DDBs proteins in plants.
Method: Bioinformatics tools had been used in this work to analyses DNA Damage-Binding proteins;
MSA, Phylogenetic tree construction, 3-D structure prediction, Domain analysis, subcellular
localization prediction, Interactome analysis and docking sites.
Result: DDB1a and DDB1b are closely related, while DDB2 protein is on the other branch, which
further confirms our previous results about the homology present between proteins DDB1a and
DDB1b. We found two domains of AtDDB1a and AtDDB1b. These are MMS1_N and CPSF_A; 464
and 314 amino acids long, respectively. AtDDB2 was identified with ten domains – two zinc fingers
and five WD40 domains with three simple regions interspersed between them. DDB1a and DDB1b
interact with much more proteins when compared to DDB2. In fact, DDB2 shows only 3 high confidence
interactions, two of which are with DDB1a and DDB1b. Interesting result is that the only additional
protein DDB2 interacts with is CUL4, which is a protein involved in ubiquitination.
Conclusion: This study shed new light to that puzzle through development and analysis of the interactome
of DDB proteins. Most importantly, the interaction of E3-ligase-forming complex (AtDDB1
– CUL4 – CSA) was confirmed. This is extremely important since E3-ligase is a key player in DNA
repair mechanism. In addition, beside the legendary role of DDBs proteins in DNA-repair mechanism,
they play other important roles in negative regulation of abscisic acid ABA and ABA-mediated
developmental responses, including inhibition of seed germination, seedling establishment, and root