In silico approach on structural and functional characterization of heat shock protein from Sulfobacillus acidophilus.

Abstract

The 70 kDa heat shock proteins (Hsp70 s) are highly conserved and ubiquitous molecular chaperones. Hsp70 proteins are intimately involved in different biological activities including maintaining protein homeostasis and resisting environmental stress for survival. Characterizations of eukaryotic Hsp70 s with diverse functions are well established but investigations needed for prokaryotes. For better understanding, the sequences of Sulfobacillus acidophilus were retrieved from UniProt. Retrieved stress proteins were renamed as SaHsp70 s and performed an in silico analysis to identify sequential, structural properties and functional attributes. The in silico characterization of these proteins revealed that they are acidic, mostly thermostable globular protein with NAD(P)-binding Rossmann-folding. Molecular mass of SaHsp70 s ranged from 31.9 to 68.5 kDa and mainly localized in the cytoplasm. Phylogeny revealed the evolutionary distance and relationship among retrieved proteins. Domain analyzed only SaHsp70 - 1, SaHsp70 - 3, and SaHsp70 - 14 have actual conserved domain for Hsp70 and share the same clade on phylogenetic tree. Major part of each protein was abundant with α-helix and random coil which make it thermally stable and suitable for interacting with other proteins. SAVES and ProSA server proves the reliability, stability, and consistency tertiary structure of SaHsp70 s. Functional analysis was done in terms of membrane protein topology, PPI network generation, active and proteolytic cleavage sites prediction, conserved motif and domain detection. CastP predicted Gly, Lys, Thr, Glu, Pro, Gln, Arg and Val act as catalytic residue, are important for metal ions binding. Intramolecular interaction analysis suggested Lys67, Thr12, Thr170, Gly 168, Gly 169, and Glu 141 of SaHsp70 - 14 proteins could play central role in various complex cellular functions like stress mitigation, thermal stability, and related developmental processes.