Effects of heat shock protein CLPC’S ɑ4-β2 loop deletion from an alkaliphilic Bacillus lehensis G1 on its stability and activity

• Main Authors: Rashid, S. A., Bakar, F. D. A., Murad, A. M. A., Illias, R. M.
• Format: Article
• Published: Penerbit UTM Press 2017
• Subjects: TP Chemical technology
• Online Access: http://eprints.utm.my/id/eprint/76703/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021067466&doi=10.11113%2fjt.v79.11100&partnerID=40&md5=f36ee91e4ea048468f588a327e6223a0
• Institution: Universiti Teknologi Malaysia

Protein loops are frequently considered as critical determinants that influence not only the function but also the structure of a protein. Bacillus lehensis G1 ClpC (WT) has a four-residue insertion at the ɑ4-β2 loop, which is absent in Bacillus subtillis ClpC. To foster a deep understanding of the significance of additional residues in the structure and function of ClpC, a deletion mutation involving residues 76-79 (∆76-79) was constructed. Circular dichroism spectroscopy was used to evaluate the structural perturbations associated with the deletion. The results demonstrated that, the precise configuration of the ɑ4-β2 loop is important for maintaining the structure and function of WT. ∆76-79 leads to severe global destabilisation and unfolding of the secondary structure of the protein, which decreases ATPase activity. The optimum temperature for ∆76-79 is 25 °C, down from 45 °C for WT. The results suggest that the additional four residues at the ɑ4-β2 loop are critical for WT’s structure and function.