Molecular, biochemical and kinetic analysis of a novel, thermostable lipase (LipSm) from Stenotrophomonas maltophilia Psi-1, the first member of a new bacterial lipase family (XVIII)

Maria Parapouli; Athanasios Foukis; Panagiota-Yiolanda Stergiou; Maria Koukouritaki; Panagiotis Magklaras; Olga A Gkini; Emmanuel M Papamichael; Amalia-Sofia Afendra; Efstathios Hatziloukas

doi:10.1186/s40709-018-0074-6

Molecular, biochemical and kinetic analysis of a novel, thermostable lipase (LipSm) from Stenotrophomonas maltophilia Psi-1, the first member of a new bacterial lipase family (XVIII)

J Biol Res (Thessalon). 2018 Feb 8:25:4. doi: 10.1186/s40709-018-0074-6. eCollection 2018 Dec.

Authors

Maria Parapouli¹, Athanasios Foukis¹, Panagiota-Yiolanda Stergiou¹, Maria Koukouritaki¹, Panagiotis Magklaras¹, Olga A Gkini¹, Emmanuel M Papamichael¹, Amalia-Sofia Afendra¹, Efstathios Hatziloukas^{1

2}

Affiliations

¹ 1Enzyme Biotechnology and Genetic Engineering Group, University of Ioannina, 451 10 Ioannina, Greece.
² 2Department of Biological Applications & Technologies, University of Ioannina, University Campus, 451 10 Ioannina, Greece.

Abstract

Background: Microbial lipases catalyze a broad spectrum of reactions and are enzymes of considerable biotechnological interest. The focus of this study was the isolation of new lipase genes, intending to discover novel lipases whose products bear interesting biochemical and structural features and may have a potential to act as valuable biocatalysts in industrial applications.

Results: A novel lipase gene (lipSm), from a new environmental Stenotrophomonas maltophilia strain, Psi-1, originating from a sludge sample from Psittaleia (Greece), was cloned and sequenced. lipSm was further overexpressed in E. coli BL21(DE3) and the overproduced enzyme LipSm was purified and analyzed in respect to its biochemical and kinetic properties. In silico analysis of LipSm revealed that it is taxonomically related to several uncharacterized lipases from different genera, which constitute a unique clade, markedly different from all other previously described bacterial lipase families. All members of this clade displayed identical, conserved consensus sequence motifs, i.e. the catalytic triad (S, D, H), and an unusual, amongst bacterial lipases, Y-type oxyanion hole. 3D-modeling revealed the presence of a lid domain structure, which allows LipSm to act on small ester substrates without interfacial activation. In addition, the high percentage of alanine residues along with the occurrence of the AXXXA motif nine times in LipSm suggest that it is a thermostable lipase, a feature verified experimentally, since LipSm was still active after heating at 70 °C for 30 min.

Conclusions: The phylogenetic analysis of LipSm suggests the establishment of a new bacterial lipase family (XVIII) with LipSm being its first characterized member. Furthermore, LipSm is alkaliphilic, thermostable and lacks the requirement for interfacial activation, when small substrates are used. These properties make LipSm a potential advantageous biocatalyst in industry and biotechnology.

Keywords: Bacterial lipase families; Enzyme kinetics; Enzyme purification; Lipase gene cloning and overexpression; Stenotrophomonas maltophilia; Thermostable bacterial lipase.