title: Isolation and characterization of cold-active family VIII esterases from an arctic soil metagenome.
abstract: Functional screening for lipolytic enzymes at low temperatures resulted in the isolation of the novel cold-active esterases, EstM-N1 and EstM-N2, from a metagenomic DNA library of arctic soil samples. EstM-N1 and EstM-N2 were 395 and 407 amino acids in length, respectively, and showed the highest similarity to class C β-lactamases. However, they shared a relatively low level of sequence similarity (30%) with each other. Phylogenetic analysis of bacterial lipolytic enzymes confirmed that EstM-N1 and EstM-N2 belonged to family VIII of bacterial esterases/lipases. The (His)(6)-tagged esterases were purified to about 99% homogeneity from the soluble fraction of recombinant Escherichia coli cultures. The purified EstM-N1 and EstM-N2 retained more than 50% of maximal activity in the temperature range of 0-35 °C, with optimal temperatures of 20 °C and 30 °C, respectively. Both enzymes preferred the short acyl chains of p-nitrophenyl esters and exhibited very narrow substrate specificity, indicating that they are typical esterases. The β-lactamase activity of EstM-N1 and EstM-N2 was also detected and reached about 31% and 13% of the positive control enzyme, Bacillus cereus β-lactamase, respectively. These first cold-active esterases belonging to family VIII are expected to be useful for potential biotechnological applications as interesting biocatalysts.
authors.affiliation: Chemical Biotechnology Research Center, Korea Research Institute of Chemical Technology, P.O. Box 107, Sinseongno 19, Yuseong, Daejeon 305-600, South Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Yu
authors.forename: Min-A
authors.initials: MA
authors.lastname: Kwon
authors.forename: Miae
authors.initials: M
authors.lastname: Lee
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Oh
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Choi
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Bong-Keun
authors.initials: BK
authors.lastname: Song
authors.forename: Dae-Hyun
authors.initials: DH
authors.lastname: Hahm
authors.forename: Jae Kwang
authors.initials: JK
authors.lastname: Song
mesh_terms: D001110:Arctic Regions; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001669:Biochemical Phenomena; D003001:Cloning, Molecular; D003080:Cold Temperature; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D004950:Esterases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D015698:Genomic Library; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000235:genetics / Q000378:metabolism; D054892:Metagenome; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012987:Soil; D004950:Esterases; D008049:Lipase; D001618:beta-Lactamases