Abstract
BackgroundHalophiles are extremophilic microorganisms growing optimally at high salt concentrations. There are two strategies used by halophiles to maintain proper osmotic pressure in their cytoplasm: accumulation of molar concentrations of potassium and chloride with extensive adaptation of the intracellular macromolecules ("salt-in" strategy) or biosynthesis and/or accumulation of organic osmotic solutes ("osmolyte" strategy). Our work was aimed at contributing to the understanding of the shared molecular mechanisms of protein haloadaptation through a detailed and systematic comparison of a sample of several three-dimensional structures of halophilic and non-halophilic proteins. Structural differences observed between the "salt-in" and the mesophilic homologous proteins were contrasted to those observed between the "osmolyte" and mesophilic pairs.ResultsThe results suggest that haloadaptation strategy in the presence of molar salt concentration, but not of osmolytes, necessitates a weakening of the hydrophobic interactions, in particular at the level of conserved hydrophobic contacts. Weakening of these interactions counterbalances their strengthening by the presence of salts in solution and may help the structure preventing aggregation and/or loss of function in hypersaline environments.ConclusionsConsidering the significant increase of biotechnology applications of halophiles, the understanding of halophilicity can provide the theoretical basis for the engineering of proteins of great interest because stable at concentrations of salts that cause the denaturation or aggregation of the majority of macromolecules.
Highlights
Halophiles are extremophilic microorganisms growing optimally at high salt concentrations
The accepted view [6] distinguishes the halophilic organisms in: extreme halophiles, borderline extreme halophiles, moderate halophiles, and halotolerant microorganisms that do not show an absolute requirement for salt for growth but grow well up to often very high salt concentrations
Scrutiny of proteome and genomic sequences may not unravel subtle differences at the three-dimensional structural level while structural analysis of a single or few protein families may lack sufficient generalization. For these reasons we report in this work a systematic comparison between the available three-dimensional structures of halophilic enzymes deposited in the data banks and the structure of one of their homologues, to investigate the differences possibly related to shared strategies of structural adaptation to high salt environments
Summary
Halophiles are extremophilic microorganisms growing optimally at high salt concentrations. The environmental challenges that extremophilic organisms have to face necessitate, besides other physiological modifications, biosynthesis of macromolecules stable and active at environmental physical-chemical extreme conditions. These macromolecules display clearly distinguished features when compared to the macromolecules from. Halophilic microorganisms are salt-loving extremophilic organisms that grow optimally at high salt concentrations. They were found [6] mainly in marine salterns and hypersaline lakes, such as the Great Salt Lake and the Dead Sea. A survey of the salt requirements in the microbial world shows a continuum of properties which makes it very difficult to define by sharp limits what a halophilic microorganism is. The accepted view [6] distinguishes the halophilic organisms in: extreme halophiles (growing best in media containing 2.5-5.2 M salt), borderline extreme halophiles (growing best is media containing 1.5-4.0 M salt), moderate halophiles (growing best in media containing 0.5-2.5 M salt), and halotolerant microorganisms that do not show an absolute requirement for salt for growth but grow well up to often very high salt concentrations (considered extremely halotolerant if the growth range extends above 2.5 M salt)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
