Are Repetitive Motifs of LEAp Chaperones the Main Bodyguards ofTarget Proteins?: in silico Prediction

Severe water stress, either through freezing or drying, leads to protein unfolding and subsequent cell damage. LEA proteins are involved in providing protection to biological macromolecules during water loss. Among animals, LEA group ۱ proteins have been reported only in Artemia as a unique stress model in animals. AfLEA۱ interacts with other proteins and nucleic acids . In addition, it protects the enzyme lactate dehydrogenase (LDH) during drying [۱,۲]. Experiments: I-Tasser (https:zhanggroup.org/I-TASSER) predicts the structure of proteins by comparing parts of known crystal structures available from the protein data bank to the investigated polypeptide and combining them into models using a hierarchical prediction. Based on TM-score, RMSD and C-score parameters, the best model was selected for the docking process and HADDOCK web server (https://wenmr.science.uu.nl/haddock۲.۴/) was used to investigate protein-protein interaction. Active and passive residues were predicted using the CPORT server (https:alcazar.science.uu.nl/services/CPORT). Results:The model provided by I-TASSER structurally includes ۳۰% random coil and ۷۰% ↵-helix. ۶۳% of its residues are on the surface and exposed to the solvent, and ۳۷% of the residues are buried in the structure. The target protein has a more flexible structure than other regions in regions with a random coil structure and at the N and C-terminus of the amino acid sequence, which interacts with the lactate dehydrogenase protein substrate through ۱۴ hydrogen bonds, ۴ salt bridges and ۱۸۸ non-bonded interactions. Conclusion:LEAPs are highly specialized in confronting water-deficiency conditions. In spite of considerable research, the mechanism of action of LEAs to confer tolerance against abiotic stresses still remains obscure. Based on our findings, their highly repetitive structure are involved in binding to and protecting the target protein during desiccation to maintain its proper folding. The repetitive motifs in LEA۱ may further act as multivalent sites for protein–protein, and protein–RNA interactions.

کلیدواژه ها:

LEAp ، Dessication tolerance ، HADDOCK ، I-TASSER ، CPORT ، Chaperone activity ، repetitive motif