Suchergebnisse

The recent suggestion of phosphine in Venus's atmosphere has regenerated interest in the idea of life in clouds. However, such analyses usually neglect the role of water activity, which is a measure of the relative availability of water, in habitability. Here we compute the water activity within the clouds of Venus and other Solar System planets from observations of temperature and water-vapour abundance. We find water-activity values of sulfuric acid droplets, which constitute the bulk of Venus's clouds, of ≤0.004, two orders of magnitude below the 0.585 limit for known extremophiles. Considering other planets, ice formation on Mars imposes a water activity of ≤0.537, slightly below the habitable range, whereas conditions are biologically permissive (>0.585) at Jupiter's clouds (although other factors such as their composition may play a role in limiting their habitability). By way of comparison, Earth's troposphere conditions are, in general, biologically permissive, whereas the atmosphere becomes too dry for active life above the middle stratosphere. The approach used in the current study can also be applied to extrasolar planets. ; We are grateful to S. L. Clegg (University of East Anglia, England, UK) for helpful discussions on the use of the E-AIM at low water activity and the provision of some code; C. S. Cockell (University of Edinburgh, Scotland, UK), D. Y. Sorokin (Winogradsky Institute of Microbiology, Russia) and A. Ventosa (University of Seville, Spain) for providing information about thermotolerance of halophiles; M. S. Marley (NASA Ames Research Center, CA, USA) for information on Jupiter and exoplanets; A. Méndez (University of Puerto Rico, Puerto Rico) for inputs relating to analysis of Earth's atmosphere; J. R. Lobry (University of Lyons, France) who helped with use of the cardinal pH model; N. J. Tosca (University of Cambridge, England, UK) for discussions about thermodynamic properties of aqueous sulfuric acid solutions; and E. L. J. Watkin (Curtin University, Australia) who provided information about stress tolerance of Acidihalobacter. J.E.H. was funded by the Biotechnology and Biological Sciences Research Council (BBSRC, United Kingdom) project BBF003471; M.-P.Z. was supported by projects PID2019-104205GB-C21 of Ministry of Science and Innovation and MDM-2017-0737 Unidad de Excelencia 'María de Maeztu'- Centro de Astrobiología (CSIC-INTA) (Spain); and O.V.G. was supported by the Centre of Environmental Biotechnology Project (grant 810280) funded by the European Regional Development Fund (ERDF) through the Welsh Government.

© 2013 Macmillan Publishers Limited ; Ubiquitous bacteria from the genus Oleispira drive oil degradation in the largest environment on Earth, the cold and deep sea. Here we report the genome sequence of Oleispira antarctica and show that compared with Alcanivorax borkumensis—the paradigm of mesophilic hydrocarbonoclastic bacteria—O. antarctica has a larger genome that has witnessed massive gene-transfer events. We identify an array of alkane monooxygenases, osmoprotectants, siderophores and micronutrient-scavenging pathways. We also show that at low temperatures, the main protein-folding machine Cpn60 functions as a single heptameric barrel that uses larger proteins as substrates compared with the classical double-barrel structure observed at higher temperatures. With 11 protein crystal structures, we further report the largest set of structures from one psychrotolerant organism. The most common structural feature is an increased content of surface-exposed negatively charged residues compared to their mesophilic counterparts. Our findings are relevant in the context of microbial cold-adaptation mechanisms and the development of strategies for oil-spill mitigation in cold environments. ; We acknowledge the funding from the EU Framework Program 7 to support Projects MAMBA (226977), ULIXES (266473), MAGIC PAH (245226) and MICROB3 (287589) This work received the support of the Government of Canada through Genome Canada and the Ontario Genomics Institute (grant 2009-OGI-ABC-1405 to A.F.Y. and A.S.), and the U.S. Government National Institutes of Health (grants GM074942 and GM094585 (to A.S. through Midwest Center for Structural Genomics). The study was supported by the Max Planck Society and the Deutsche Forschungsgemeinschaft through project KU 2679/2-1 and BU 890/21-1. ; Peer Reviewed

Esterases receive special attention because of 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 rank (classify) the 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 data sets. ; C.C. thanks the Spanish Ministry of Economy, Industry and Competitiveness for a Ph.D. fellowship (Grant BES-2015-073829). This project received funding from the European Union's Horizon 2020 research and innovation program [Blue Growth: Unlocking the potential of Seas and Oceans] under grant agreement no. 634486 (project acronym INMARE). This research was also supported by the European Community Projects MAGICPAH (FP7-KBBE-2009-245226), ULIXES (FP7-KBBE-2010-266473), and KILLSPILL (FP7-KBBE2012-312139) and grants BIO2011-25012, PCIN-2014-107, BIO2014-54494-R, and CTQ2016-79138-R from the Spanish Ministry of Economy, Industry and Competitiveness. The present investigation was also funded by the Spanish Ministry of Economy, Industry and Competitiveness within the ERA NET IB2, grant no. ERA-IB-14-030 (MetaCat), the UK Biotechnology and Biological Sciences Research Council (BBSRC), grant no. BB/M029085/1, and the German Research Foundation (FOR1296). R.B. and P.N.G. acknowledge the support of the Supercomputing Wales project, which is part-funded by the European Regional Development Fund (ERDF) via the Welsh Government. O.V.G. and P.N.G. acknowledge the support of the Centre of Environmental Biotechnology Project funded by the European Regional Development Fund (ERDF) through the Welsh Government. A.Y. and A.S. gratefully acknowledge funding from Genome Canada (2009-OGI-ABC-1405) and the NSERC Strategic Network grant IBN. A.I.P. was supported by the Counseling of Economy and Employment of the Principality of Asturias, Spain (Grant FC-15-GRUPIN14-107). V.G. acknowledges the joint BSC-CRG-IRB Research Program in Computational Biology. The authors gratefully acknowledge financial support provided by the European Regional Development Fund (ERDF). ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed