title: A novel, extremely alkaliphilic and cold-active esterase from Antarctic desert soil.
abstract: A novel, cold-active and highly alkaliphilic esterase was isolated from an Antarctic desert soil metagenomic library by functional screening. The 1,044 bp gene sequence contained several conserved regions common to lipases/esterases, but lacked clear classification based on sequence analysis alone. Moderate (<40%) amino acid sequence similarity to known esterases was apparent (the closest neighbour being a hypothetical protein from Chitinophaga pinensis), despite phylogenetic distance to many of the lipolytic "families". The enzyme functionally demonstrated activity towards shorter chain p-nitrophenyl esters with the optimal activity recorded towards p-nitrophenyl propionate (C3). The enzyme possessed an apparent T(opt) at 20°C and a pH optimum at pH 11. Esterases possessing such extreme alkaliphily are rare and so this enzyme represents an intriguing novel locus in protein sequence space. A metagenomic approach has been shown, in this case, to yield an enzyme with quite different sequential/structural properties to known lipases. It serves as an excellent candidate for analysis of the molecular mechanisms responsible for both cold and alkaline activity and novel structure-function relationships of esterase activity.
authors: Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Modderdam Road, Bellville, Cape Town, South Africa.
authors: Xiao Ping
authors: XP
authors: Hu
authors: Caroline
authors: C
authors: Heath
authors: Mark Paul
authors: MP
authors: Taylor
authors: Marla
authors: M
authors: Tuffin
authors: Don
authors: D
authors: Cowan
mesh_terms: D000595:Amino Acid Sequence; D000864:Antarctic Regions; D001483:Base Sequence; D003080:Cold Temperature; D017931:DNA Primers; D004950:Esterases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D056186:Metagenomics; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D012988:Soil Microbiology
chemical_list: D017931:DNA Primers; D004950:Esterases