Abstract
Simple SummaryInteractions of ligands with proteins are central to all reactions in the biological cell. How such reactions are affected by harsh environmental conditions, such as low temperatures, high pressures, and high concentrations of biologically destructive salts, is still largely unknown. Our work focused on specific salts found on Mars to understand whether the planet’s potentially liquid, water-rich subsurface harbors conditions that are theoretically favorable for life. Our data show that, while magnesium chloride and sulfate do not significantly alter protein–ligand interactions, the perchlorate ion strongly affects protein–ligand binding. However, the temperature and pressure conditions encountered on Mars do not necessarily preclude protein–ligand interactions of the type studied here.Protein–ligand interactions are fundamental to all biochemical processes. Generally, these processes are studied at ambient temperature and pressure conditions. We investigated the binding of the small ligand 8-anilinonaphthalene-1-sulfonic acid (ANS) to the multifunctional protein bovine serum albumin (BSA) at ambient and low temperatures and at high pressure conditions, in the presence of ions associated with the surface and subsurface of Mars, including the chaotropic perchlorate ion. We found that salts such as magnesium chloride and sulfate only slightly affect the protein–ligand complex formation. In contrast, magnesium perchlorate strongly affects the interaction between ANS and BSA at the single site level, leading to a change in stoichiometry and strength of ligand binding. Interestingly, both a decrease in temperature and an increase in pressure favor the ligand binding process, resulting in a negative change in protein–ligand binding volume. This suggests that biochemical reactions that are fundamental for the regulation of biological processes are theoretically possible outside standard temperature and pressure conditions, such as in the harsh conditions of the Martian subsurface.
Highlights
Owing to the inherent complexity of the process, many aspects of ligand binding have not been fully explored, yet. This is true for complex solution conditions, such as ligand binding in cellulo or in the presence of high concentrations of co-solutes or at extreme environmental conditions, such as at low/high temperatures and high hydrostatic pressures (HHP)
In order to investigate the impact of the Mars-relevant salts on the complex formation between ANS and bovine serum albumin (BSA), we performed a series of fluorescence spectroscopic experiments
We have found that the binding of a small aromatic ligand such as ANS to an archetypical multifunctional protein, BSA, depends significantly on temperature, and on the type of salt and, to a lesser extent, on pressure
Summary
Protein–ligand recognition and binding are fundamental to all biochemical processes and are essential for all life forms [1,2,3,4,5]. Protein–ligand interactions may not strictly follow a simple binding process; instead, they may be accompanied by conformational as well as hydration changes of the protein and potentially the ligand. Owing to the inherent complexity of the process, many aspects of ligand binding have not been fully explored, yet. This is true for complex solution conditions, such as ligand binding in cellulo or in the presence of high concentrations of co-solutes or at extreme environmental conditions, such as at low/high temperatures and high hydrostatic pressures (HHP). Knowledge about high hydrostatic pressure effects on biological systems is fundamental for our understanding of life being exposed to such harsh conditions and of the physical limits of life in general [6,7,8,9,10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
