title: A novel thermophilic and halophilic esterase from Janibacter sp. R02, the first member of a new lipase family (Family XVII).
abstract: Janibacter sp. strain R02 (BNM 560) was isolated in our laboratory from an Antarctic soil sample. A remarkable trait of the strain was its high lipolytic activity, detected in Rhodamine-olive oil supplemented plates. Supernatants of Janibacter sp. R02 displayed superb activity on transesterification of acyl glycerols, thus being a good candidate for lipase prospection. Considering the lack of information concerning lipases of the genus Janibacter, we focused on the identification, cloning, expression and characterization of the extracellular lipases of this strain. By means of sequence alignment and clustering of consensus nucleotide sequences, a DNA fragment of 1272bp was amplified, cloned and expressed in E. coli. The resulting recombinant enzyme, named LipJ2, showed preference for short to medium chain-length substrates, and displayed maximum activity at 80°C and pH 8-9, being strongly activated by a mixture of Na+and K+. The enzyme presented an outstanding stability regarding both pH and temperature. Bioinformatics analysis of the amino acid sequence of LipJ2 revealed the presence of a consensus catalytic triad and a canonical pentapeptide. However, two additional rare motifs were found in LipJ2: an SXXL β-lactamase motif and two putative Y-type oxyanion holes (YAP). Although some of the previous features could allow assigning LipJ2 to the bacterial lipase families VIII or X, the phylogenetic analysis showed that LipJ2 clusters apart from other members of known lipase families, indicating that the newly isolated Janibacter esterase LipJ2 would be the first characterized member of a new family of bacterial lipases.
authors.affiliation: Bioscience Department, Facultad de Química, Universidad de la República, Gral. Flores 2124, 11800 Montevideo, Uruguay.
authors.forename: Agustín
authors.initials: A
authors.lastname: Castilla
authors.affiliation: Bioscience Department, Facultad de Química, Universidad de la República, Gral. Flores 2124, 11800 Montevideo, Uruguay.
authors.forename: Paola
authors.initials: P
authors.lastname: Panizza
authors.affiliation: Bioscience Department, Facultad de Química, Universidad de la República, Gral. Flores 2124, 11800 Montevideo, Uruguay.
authors.forename: Diego
authors.initials: D
authors.lastname: Rodríguez
authors.affiliation: Bioscience Department, Facultad de Química, Universidad de la República, Gral. Flores 2124, 11800 Montevideo, Uruguay.
authors.forename: Luis
authors.initials: L
authors.lastname: Bonino
authors.affiliation: Dept. Genetics, Microbiology & Statistics, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Díaz
authors.affiliation: Bioscience Department, Facultad de Química, Universidad de la República, Gral. Flores 2124, 11800 Montevideo, Uruguay.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Irazoqui
authors.affiliation: Bioscience Department, Facultad de Química, Universidad de la República, Gral. Flores 2124, 11800 Montevideo, Uruguay. Electronic address: soniar@fq.edu.uy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Rodríguez Giordano
mesh_terms: D039903:Actinobacteria / Q000201:enzymology* / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D004950:Esterases / Q000145:classification / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008049:Lipase / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D008958:Models, Molecular; D010802:Phylogeny
chemical_list: D001426:Bacterial Proteins; D004950:Esterases; D008049:Lipase
keywords: Esterase; Halophilic; Janibacter; Thermophilic