Ig-like Domain in Endoglucanase Cel9A from Alicyclobacillus acidocaldarius Makes Dependent the Enzyme Stability on Calcium

Endoglucanase Cel9A from Alicyclobacillus acidocaldarius (AaCel9A) has an Ig-like domain and the enzyme stability is dependent to calcium. In this study the effect of calcium on the structure and stability of the wild-type enzyme and the truncated form (the wild-type enzyme without Ig-like domain, A...

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Bibliographic Details
Published in:Molecular biotechnology 2018-09, Vol.60 (9), p.698-711
Main Authors: Pazhang, Mohammad, Younesi, Fereshteh S., Mehrnejad, Faramarz, Najavand, Saeed, Tarinejad, Alireza, Haghi, Mehrnaz, Rashno, Fatemeh, Khajeh, Khosro
Format: Article
Language:English
Subjects:
Binding sites
Biochemistry
Biological Techniques
Biotechnology
Bonding
Calcium
Calcium-binding protein
Cell Biology
Chemistry
Chemistry and Materials Science
Endoglucanase
Enzymes
Flexibility
Fluorescence
Human Genetics
Hydrogen bonding
Hydrogen bonds
Original Paper
Protein Science
Rigidity
Structural stability
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Summary:Endoglucanase Cel9A from Alicyclobacillus acidocaldarius (AaCel9A) has an Ig-like domain and the enzyme stability is dependent to calcium. In this study the effect of calcium on the structure and stability of the wild-type enzyme and the truncated form (the wild-type enzyme without Ig-like domain, AaCel9AΔN) was investigated. Fluorescence quenching results indicated that calcium increased and decreased the rigidity of the wild-type and truncated enzymes, respectively. RMSF results indicated that AaCel9A has two flexible regions (regions A and B) and deleting the Ig-like domain increased the truncated enzyme stability by decreasing the flexibility of region B probably through increasing the hydrogen bonds. Calcium contact map analysis showed that deleting the Ig-like domain decreased the calcium contacting residues and their calcium binding affinities, especially, in region B which has a role in calcium binding site in AaCel9A. Metal depletion and activity recovering as well as stability results showed that the structure and stability of the wild-type and truncated enzymes are completely dependent on and independent of calcium, respectively. Finally, one can conclude that the deletion of Ig-like domain makes AaCel9AΔN independent of calcium via decreasing the flexibility of region B through increasing the hydrogen bonds. This suggests a new role for the Ig-like domain which makes AaCel9A structure dependent on calcium.
ISSN:1073-6085
1559-0305
DOI:10.1007/s12033-018-0105-4