Proteins under pressure

Abstract

Oceans not only cover the major part of the earth's surface but also reach into depths exceeding the height of the Mt Everest. They are populated down to the deepest levels (=11800 m), which means that a significant proportion of the global biosphere is exposed to pressures of up to 120 MPa. Although this fact has been known for more than a century, the ecology of the 'abyss' is still in its infancy. Only recently, barophilic adaptation, i.e. the requirement of elevated pressure for viability, has been firmly established. In non-adapted organisms, increased pressure leads to morphological anomalies or growth inhibition, and ultimately to cell death. The detailed molecular mechanism of the underlying 'metabolic dislocation' is unresolved.Effects of pressure as a variable in microbiology, biochemistry and biotechnology allow the structure/function relationship of proteins and protein conjugates to be analyzed. In this context, stabilization by cofactors or accessory proteins has been observed. High-pressure equipment available today allows the comprehensive characterization of the behaviour of proteins under pressure. Single-chain proteins undergo pressure-induced denaturation in the 100-MPa range, which, in the case of oligomeric proteins or protein assemblies, is preceded by dissociation at lower pressure. The effects may be ascribed to the positive reaction volumes connected with the formation of hydrophobic and ionic interactions. In addition, the possibility of conformational effects exerted by moderate, non-denaturing pressures, and related to the intrinsic compressibility of proteins, is discussed. Crystallization may serve as a model reaction of protein self-organization. Kinetic aspects of its pressureinduced inhibition can be described by a model based on the Oosawa theory of molecular association. Barosensitivity is known to be correlated with the pressure-induced inhibition of protein biosynthesis. Attempts to track down the ultimate cause in the dissociation of ribosomes have revealed remarkable stabilization of functional complexes under pseudo-physiological conditions, with the post-translational complex as the most pressure-sensitive species. Apart from the key issue of barosensitivity and barophilic adaptation, high-pressure biochemistry may provide means to develop new approaches to nonthermic industrial processes, especially in the field of food technology.Life in the deep sea faces a whole set of unfavourable conditions, including pressures up to 120 MPa (1200 bar), temperatures around 2°C or, in volcanic regions, above 1OO"C, absence of sunlight, and scarce supply of organic nutrients. When 'deep' means deeper than 1000 m, these biotopes include more than half (~6 2 % ) of the volume of the global biosphere (Jannasch and Taylor, 1984). The average pressure on the ocean floor is of the order of 38 MPa, indicatCorrespondence to R. Jaenicke,

Effects of pressure on the structure of metmyoglobin: Molecular dynamics predictions for pressure unfolding through a molten globule intermediate

“…Experimental techniques such as optical spectroscopy, Raman scattering, and NMR have been used to observe pressure effects on proteins (Weber & Drickamer, 1983;Frauenfelder et al, 1990;Jaenicke, 1991;Silva & Weber, 1993;Gross & Jaenicke, 1994 . The pressure denaturation of monomeric proteins, the dissociation of oligomers, and the effects of pressure on macromolecular assemblages have provided insights into the microscopic mechanism of protein folding and the role of solvent in this process (Zipp & Kauzmann, 1973;Li et al, 1976;Chryssomallis et al, 1981;Weber & Drickamer, 1983;Silva et al, 1986;Silva & Weber, 1993;Weber, 1993;Dufour et al, 1994;Peng et al, 1994;Schulte et al, 1995;Silva et al, 1996).…”

Evolution under pressure and the adaptation of visual pigment compressibility in deep-sea environments

“…Life, including macrofauna, is found at all depths, an observation that belies the extent to which pressure can affect biological function. Increasing pressure affects fundamental cellular processes such as enzyme activity, action potential propagation, synaptic transmission, and overall protein function and regulation (Campenot, 1975;Gross and Jaenicke, 1994;Somero, 1992).…”

“…Intrinsic amino acid changes that increase protein stability are also documented in several marine fish. A number of cytosolic proteins have been investigated in both shallow and deep living species (Stefanni et al, 2014), including lactate dehydrogenase (Brindley et al, 2008;Campenot, 1975;Gross and Jaenicke, 1994;Hennessey and Siebenaller, 1987;Somero, 1992), -actin (Morita, 2010;Swezey and Somero, 1982;Wakai et al, 2014), and myosin heavy chain proteins (Morita, 2010). These studies have demonstrated that proteins from deep-sea species are functionally less susceptible to increased pressure than those from shallow living species.…”

Investigation on solubilization protocols in the refolding of the thioredoxin TsnC from Xylella fastidiosa by high hydrostatic pressure approach

“…intermolecular electrostatic and hydrophobic interactions, dissociating oligomeric and aggregated proteins. The same kind of interactions that maintain the aggregated states also preserve the secondary and tertiary protein structures in their native conformation [5][6][7]. However, more efficient protein hydration followed by disruption of intramolecular bonds and subsequent protein denaturation generally requires pressure higher than 4 and 5 kbar [8].…”