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Article

Understanding High-Salt and Cold Adaptation of a Polyextremophilic Enzyme

1
KAUST Catalysis Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
2
Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering (BESE), Thuwal 23955-6900, Saudi Arabia
3
Department of Sciences and Technologies, University Parthenope of Naples, Centro Direzionale Isola C4, I-80143 Naples, Italy
4
Centre de Biochimie Structurale, CNRS, INSERM, Université de Montpellier, 34090 Montpellier, France
*
Authors to whom correspondence should be addressed.
Microorganisms 2020, 8(10), 1594; https://doi.org/10.3390/microorganisms8101594
Received: 16 September 2020 / Revised: 30 September 2020 / Accepted: 1 October 2020 / Published: 16 October 2020
(This article belongs to the Special Issue Extremophiles and Extremozymes in Academia and Industries)
The haloarchaeon Halorubrum lacusprofundi is among the few polyextremophilic organisms capable of surviving in one of the most extreme aquatic environments on Earth, the Deep Lake of Antarctica (−18 °C to +11.5 °C and 21–28%, w/v salt content). Hence, H. lacusprofundi has been proposed as a model for biotechnology and astrobiology to investigate potential life beyond Earth. To understand the mechanisms that allow proteins to adapt to both salinity and cold, we structurally (including X-ray crystallography and molecular dynamics simulations) and functionally characterized the β-galactosidase from H. lacusprofundi (hla_bga). Recombinant hla_bga (produced in Haloferax volcanii) revealed exceptional stability, tolerating up to 4 M NaCl and up to 20% (v/v) of organic solvents. Despite being cold-adapted, hla_bga was also stable up to 60 °C. Structural analysis showed that hla_bga combined increased surface acidity (associated with halophily) with increased structural flexibility, fine-tuned on a residue level, for sustaining activity at low temperatures. The resulting blend enhanced structural flexibility at low temperatures but also limited protein movements at higher temperatures relative to mesophilic homologs. Collectively, these observations help in understanding the molecular basis of a dual psychrophilic and halophilic adaptation and suggest that such enzymes may be intrinsically stable and functional over an exceptionally large temperature range. View Full-Text
Keywords: extremophiles; halophiles; psychrophiles; polyextremophiles; extremozymes; X-ray crystallography; molecular dynamics simulations extremophiles; halophiles; psychrophiles; polyextremophiles; extremozymes; X-ray crystallography; molecular dynamics simulations
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MDPI and ACS Style

Karan, R.; Mathew, S.; Muhammad, R.; Bautista, D.B.; Vogler, M.; Eppinger, J.; Oliva, R.; Cavallo, L.; Arold, S.T.; Rueping, M. Understanding High-Salt and Cold Adaptation of a Polyextremophilic Enzyme. Microorganisms 2020, 8, 1594. https://doi.org/10.3390/microorganisms8101594

AMA Style

Karan R, Mathew S, Muhammad R, Bautista DB, Vogler M, Eppinger J, Oliva R, Cavallo L, Arold ST, Rueping M. Understanding High-Salt and Cold Adaptation of a Polyextremophilic Enzyme. Microorganisms. 2020; 8(10):1594. https://doi.org/10.3390/microorganisms8101594

Chicago/Turabian Style

Karan, Ram, Sam Mathew, Reyhan Muhammad, Didier B. Bautista, Malvina Vogler, Jorg Eppinger, Romina Oliva, Luigi Cavallo, Stefan T. Arold, and Magnus Rueping. 2020. "Understanding High-Salt and Cold Adaptation of a Polyextremophilic Enzyme" Microorganisms 8, no. 10: 1594. https://doi.org/10.3390/microorganisms8101594

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