title: In silico and experimental characterization of chimeric Bacillus thermocatenulatus lipase with the complete conserved pentapeptide of Candida rugosa lipase.
abstract: Lipases are one of the highest value commercial enzymes as they have broad applications in detergent, food, pharmaceutical, and dairy industries. To provide chimeric Bacillus thermocatenulatus lipase (BTL2), the completely conserved pentapeptide (¹¹²Ala-His-Ser-Gln-Gly¹¹⁶) was replaced with similar sequences (²⁰⁷Gly-Glu-Ser-Ala-Gly²¹¹) of Candida rugosa lipase (CLR) at the nucleophilic elbow region. For this purpose, three mutations including A112G, H113E, and Q115A were inserted in the conserved pentapeptide sequence of btl2 gene. Based on the crystal structures of 2W22, the best structure of opened form of the chimeric lipases were garnered using the MODELLER v9.10 software. The native and chimeric lipases were docked to a set of ligands, and a trial version of Molegro Virtual Docker (MVD) software was used to obtain the energy values. Docking results confirmed chimeric lipase to be better than the native lipase. Following the in silico study, cloning experiments were conducted and expression of native and chimeric btl2 gene in Pichia pastoris was performed. The native and chimeric lipases were purified, and the effect of these mutations on characteristics of chimeric lipase studied and then compared with those of native lipase. Chimeric lipase exhibited 1.6-fold higher activity than the native lipase at 55 °C. The highest percentage of both lipases activity was observed at 60 °C and pH of 8.0. The ion Ca²⁺ slightly inhibited the activity of both lipases, whereas the organic solvent enhanced the lipase stability of chimeric lipase as compared with the native lipase. According to the results, the presence of two glycine residues at the conserved pentapeptide region of this chimeric lipase (¹¹²Gly-Glu-Ser-Ala-Gly¹¹⁶) may increase the flexibility of the nucleophilic elbow region and affect the enzyme activity level.
authors.affiliation: Department of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology-NIGEB, P.O. Box 14965/161, Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Hosseini
authors.forename: Ali Asghar
authors.initials: AA
authors.lastname: Karkhane
authors.forename: Bagher
authors.initials: B
authors.lastname: Yakhchali
authors.forename: Mehdi
authors.initials: M
authors.lastname: Shamsara
authors.forename: Saeed
authors.initials: S
authors.lastname: Aminzadeh
authors.forename: Dena
authors.initials: D
authors.lastname: Morshedi
authors.forename: Kamahldin
authors.initials: K
authors.lastname: Haghbeen
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Torktaz
authors.forename: Esmat
authors.initials: E
authors.lastname: Karimi
authors.forename: Zahra
authors.initials: Z
authors.lastname: Safari
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D002175:Candida; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D009842:Oligopeptides; D011993:Recombinant Fusion Proteins; D008049:Lipase