Functional Metagenomics Reveals a New Catalytic Domain, the Metallo-β-Lactamase Superfamily Domain, Associated with Phytase Activity.

摘要: Inositol-6-phosphate, also known as phytic acid, is a phosphorus source that plays several important roles in the cycle and cell metabolism. The characterized enzymes responsible for its degradation, phytases, are mostly derived from cultured individual microorganisms. catalytic signatures of phytases restricted to molecular domains four protein superfamilies: histidine phosphatases, tyrosine purple acid phosphatases β-propeller phosphatases. During function-based screening previously generated forest soil metagenomic libraries Escherichia coli clones conferring phytase activity, two positive harboring plasmids pLP05 pLP12 were detected. Analysis insert sequences revealed absence classic phosphatase/phytase proteins deduced putative genes, but genes mblp01 (pLP05) mblp02 (pLP12) encoded metallo-β-lactamases (MBLs). Several MBL representatives promiscuous with phosphoesterase activity was not reported. Both subcloned, expressed, analyzed. Mblp01 Mblp02 members lactamase B2 family. Protein modeling showed closest structural homologue both ZipD E. toward majority tested phosphorylated substrates, including phytate. maximal enzyme activities recorded at 50°C under acidic conditions 35°C neutral pH. In presence Cu2+ or SDS, strongly inhibited. Analyses minimal inhibitory concentrations β-lactam antibiotics recombinant cells carrying reduced sensitivity antibiotics.IMPORTANCE Phytic storage molecule many plant tissues, alternative phosphate rocks, it can be problematic antinutrient. comparison other sources, exhibits bioavailability. Additionally, influences functions secondary messengers acts antioxidant tumor growth prevention. enzymatic capability process phytate has been reported limited number families. This might due almost exclusive use microorganisms analyze activity. With such restriction, study complexity diversity remains incomplete. By using metagenome-derived samples, this demonstrates existence one most superfamilies, metallo-β-lactamases. Our results increase general knowledge on environmental samples could provide new avenues engineering biocatalysts.