An in-silico study of effect of mutations on amp-binding (acyl activating) site of adenylate domain of surfactin synthetase

Author: 
Sameer kumar Yadav., Ravishankar Jaiswal and Kishor Shende

Surfactin, cyclic lipopeptide is a powerful surfactant commonly used as an antibiotic and produced by gram positive endospore forming bacteria by Non-Ribosomal Protein Synthesis system. Surfactin was found to exhibit Characteristics like antibacterial, antiviral, antifungal and antimycoplasma. The optimum conformation of enzyme catalytic site in terms of geometry and potential energy with respect to amino acid change is helpful to optimize the catalysis. In present study surfactin synthetase enzyme’s 3D structure and sequence of source bacteria, Bacillus subtilis 168 were retrieved from PDB and NCBI protein sequence database, respectively. It contains 3 domains - condensation, adenylation and thioesterase. Adenylate domain contains acyl activating conserved active site, which was considered for in-silico mutation by other amino acid. The residues in structural pattern were mutated by the software ‘Swiss Pdb viewer ver. 4.12’ (spdbv) present in the region between the residue number 611 to 624 [611Y-I-M-Y-T-S-G-T-T-G-K-P-K-G624] as well as its adjacent residue. The conformational changes at catalytic site were evaluated on the basis of changed potential energy and geometry. Gromas96 force field was used to calculate the molecular energy before and after geometry optimization. Increase or decrease in total energy (inclusive of bonding and non-bonding energy) with respect amino acid change to that of wild type, were the criteria to distinguish between favorable and non–favorable mutations. We observed that mutations at P609R, A610T, T611Q, I612L, M613F, Y614Q, T615N, S616R, G617E, T618R, T619R, G620N, K621R, P622Q, K623Q, G624T, N625Q, I626N, are found to be favorable mutations P609Y, A610R, T611L, I612P, M613Y, Y613K, T615I, S616G, G617P, T618P, T619G, G620P, K621G, P622Y, K623I, G624Y, N625R, I626P are non- favorable mutations. The reported mutations were subjected to (PAST) software for principle component analysis and correspondence analysis.

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DOI: 
http://dx.doi.org/10.24327/ijcar.2018.10241.1596
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