(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Bacteria: NE > environmental samples: NE > bacterium enrichment culture clone fosmid MGS-K1: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MSNNKQTVVDTRAGKIEGYYKEGLYVFKGIPYAAPPVGELRWMPPQPVKP WEGTLQAKQFGPIAPQNEMEGGMIPPAPPQTQNEDCLFLNIWTPGLDDAR RPVMVWIHGGAFTIGSSSEPMYKASRLAARGDIVLVTINYRLGMLGFLNL REVTKGKIPATGNEGLLDQLAALNWVKENIAAFGGDPTNVTVFGESAGAM SIGCLMAMPKAKGYFHKAILESGVGSTAIPLDEAVDTARQFLETTGIKGD DVKALHELTVKDLLEAEMELRTAMAGPGEVARITVTSPVIDGELIPDVPN ELARRGSAKEVPTIIGTNLEEWKLFGIMQPDINELNEAEIVSRLSQFMSA GDAREIVKTYREARQERGEPATPFELLSAVNTDLMFRIPALGLVEAQRDN GQLAYNYLFDWKSPVMNGAIGACHALEIGFVFGQYNDMFCGSGPDADKLS GCIQDAWTTFARTGDPSCESIGKWPIYGENRMTMTLGKNCHVEEAPYEQE RQAWENISYKSAMP
Esterases receive special attention because their wide distribution in biological systems and environments and their importance for physiology and chemical synthesis. The prediction of esterases substrate promiscuity level from sequence data and the molecular reasons why certain such enzymes are more promiscuous than others, remain to be elucidated. This limits the surveillance of the sequence space for esterases potentially leading to new versatile biocatalysts and new insights into their role in cellular function. Here we performed an extensive analysis of the substrate spectra of 145 phylogenetically and environmentally diverse microbial esterases, when tested with 96 diverse esters. We determined the primary factors shaping their substrate range by analyzing substrate range patterns in combination with structural analysis and protein-ligand simulations. We found a structural parameter that helps ranking (classifying) promiscuity level of esterases from sequence data at 94% accuracy. This parameter, the active site effective volume, exemplifies the topology of the catalytic environment by measuring the active site cavity volume corrected by the relative solvent accessible surface area (SASA) of the catalytic triad. Sequences encoding esterases with active site effective volumes (cavity volume/SASA) above a threshold show greater substrate spectra, which can be further extended in combination with phylogenetic data. This measure provides also a valuable tool for interrogating substrates capable of being converted. This measure, found to be transferred to phosphatases of the haloalkanoic acid dehalogenase superfamily and possibly other enzymatic systems, represents a powerful tool for low-cost bioprospecting for esterases with broad substrate ranges, in large scale sequence datasets.
The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5 degrees C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65 degrees C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16 degrees C, was shown to contain halopiezophilic-like enzymes that are most active at 70 degrees C and with denaturing temperatures of 71.4 degrees C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes.
