The effects of hydrostatic pressure on the low-K m GTPase in brain membranes from two congeneric marine fishes

Siebenaller, Joseph F.; Murray, Thomas F.

doi:10.1007/bf00369512

Cited by 13 publications

(6 citation statements)

References 35 publications

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“…1995). Among the loci of pressure perturbation in these pathways, the intrinsic GTPase activities of the G protein a subunits are affected by increased pres-sure (Siebenaller and Murray. 1994a).…”

Section: Discussionmentioning

confidence: 99%

Hydrostatic Pressure Alters the Time Course of GTP[S] Binding to G Proteins in Brain Membranes from Two Congeneric Marine Fishes

Siebenaller

Murray

1999

The Biological Bulletin

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The effects of hydrostatic pressure on the receptor-stimulated exchange of guanosine triphosphate (GTP) for guanosine diphosphate (GDP) on the a subunit of G proteins were studied in two congeneric marine teleost fishes that differ in their depths of distribution. The poorly hydrolyzable GTP analog [35S]guanosine 5'-[gamma-thio]triphosphate ([35S]GTP[S]) was used to monitor the modulation of signal transduction by the A1 adenosine receptor agonist N6-R-(phenylisopropyl)adenosine (R-PIA) in brain membranes of the scorpaenids Sebastolobus alascanus and S. altivelis. The maximal binding (Bmax) and dissociation constant (K(d)) values, determined from equilibrium binding isotherms at atmospheric pressure (5 degrees C), were similar in the two species. The Bmax values for these species are much lower than literature values for mammalian brain tissue (25 degrees C); however, the K(d) values of the teleost and mammalian G proteins are similar. The EC50 values for the A1 adenosine receptor agonist R-PIA were similar in the two species. Hydrostatic pressure of 204 atm altered the binding of [35S]GTP[S]; basal [35S]GTP[S] binding decreased 25%. The A1 adenosine receptor agonist R-PIA and the muscarinic cholinergic receptor agonist carbamyl choline stimulated [35S]GTP[S] binding at 1 and 204 atm. At atmospheric pressure the half-time (t1/2) of [35S]GTP[S] binding differed between the two species. The GTP[S] on rate (k(on)) is larger in the shallower-living S. alascanus. Increased hydrostatic pressure altered the time course, decreasing the t1/2 in both species. The pressures that elicit this change in the time course differ between the species. However, interpolating over the range of in situ pressures the species experience, the values are similar in the two species. The guanyl nucleotide binding properties of the G protein a subunits appear to be conserved at the environmental temperatures and pressures the species experience.

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Section: Discussionmentioning

confidence: 99%

Hydrostatic Pressure Alters the Time Course of GTP[S] Binding to G Proteins in Brain Membranes from Two Congeneric Marine Fishes

Siebenaller

Murray

1999

The Biological Bulletin

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“…Pressure alters the interactions of G proteins and receptors Murray and Siebenaller, 1993;Stevens and Siebenaller, 2000), and can decrease the efficacy of agonist activation of transmembrane signaling Murray, 1994a, 1999). Pressure also inhibits adenylyl cyclase activity (Siebenaller and Murray, 1990;Siebenaller et al, 1991;Siebenaller, 2000). Each of the steps in the signaling cycle is potentially susceptible to pressure perturbation and presents an adaptational challenge.…”

Section: G-protein-coupled Signalingmentioning

confidence: 99%

Co-evolution of proteins and solutions: protein adaptation versus cytoprotective micromolecules and their roles in marine organisms

Yancey

Siebenaller

2015

Journal of Experimental Biology

128

116

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Organisms experience a wide range of environmental factors such as temperature, salinity and hydrostatic pressure, which pose challenges to biochemical processes. Studies on adaptations to such factors have largely focused on macromolecules, especially intrinsic adaptations in protein structure and function. However, micromolecular cosolutes can act as cytoprotectants in the cellular milieu to affect biochemical function and they are now recognized as important extrinsic adaptations. These solutes, both inorganic and organic, have been best characterized as osmolytes, which accumulate to reduce osmotic water loss. Singly, and in combination, many cosolutes have properties beyond simple osmotic effects, e.g. altering the stability and function of proteins in the face of numerous stressors. A key example is the marine osmolyte trimethylamine oxide (TMAO), which appears to enhance water structure and is excluded from peptide backbones, favoring protein folding and stability and counteracting destabilizers like urea and temperature. Co-evolution of intrinsic and extrinsic adaptations is illustrated with high hydrostatic pressure in deep-living organisms. Cytosolic and membrane proteins and G-protein-coupled signal transduction in fishes under pressure show inhibited function and stability, while revealing a number of intrinsic adaptations in deep species. Yet, intrinsic adaptations are often incomplete, and those fishes accumulate TMAO linearly with depth, suggesting a role for TMAO as an extrinsic 'piezolyte' or pressure cosolute. Indeed, TMAO is able to counteract the inhibitory effects of pressure on the stability and function of many proteins. Other cosolutes are cytoprotective in other ways, such as via antioxidation. Such observations highlight the importance of considering the cellular milieu in biochemical and cellular adaptation.

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“…The ligand binding to the Al receptor is markedly sensitive to temperature perturbation (Lhose et al 1984). In addition, in marine teleosts deep-living, the inhibition of adenylate cyclase activity by Al adenosine agonist was reversed at high pressure, suggesting that there may be a pressureinduced change in the coupling of G proteins to adenylate cyclase which affects an unmasking of agonist activation of the A2 adenosine receptor/Gs pathway at this pressure (Siebenaller et al 1991).…”

Section: Introductionmentioning

confidence: 99%

Biochemical and pharmacological characterization of adenosine A1 receptors in eel (Anguilla anguilla) brain

Poli

Pavan

Lucchi

et al. 1997

Fish Physiol Biochem

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N 6 -cyclohexyl[3H]adenosine ([ 3 H]CHA) was used to label adenosine Al receptors in membranes prepared from male and female eel whole brain. The Al receptor agonist [ 3 H]CHA bound saturably, reversibly and with high affinity (Kd = 0.91 ± 0.12 nM; Bma = 120.36 5.2 fmol mg 1 protein). In equilibrium competition experiments, the adenosine agonists and antagonists all displaced [ 3 H]CHA from high-affinity binding sites with the rank order of potency in displacing, characteristics of an Al adenosine receptor. Mg 2 ' dramatically increased the affinity of [ 3 H]CHA without modifying the maximal binding capacity. The specific binding was inhibited by guanosine 5'-triphosphate (K i = 2.54 i 0.98 M). The [ 3 H]CHA binding sites are ubiquitously distributed with a maximum in cerebellum and a minimum in olfactory bulb. No difference was observed between male and female brain. In eel brain, synaptosomes (P2), stimulation of adenosine 3',5'-monophosphate (cyclic AMP) accumulation with 10 -5 M forskolin was markedly reduced (45.5%) by treatment with the adenosine Al receptor agonist CHA (10 -M), and the reduction was reversed in presence of the selective Al receptor antagonist 8-cyclopentyltheophylline (10-5 M). In superfused eel cerebellar synaptosomes, K + stimulated the release of adenosine in a partially Ca 2 +-dependent manner. The findings, taken together, suggest the hypothesis that adenosine Al receptors present in eel brain could modulate synaptic transmission, as Al receptors do in other vertebrates.

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The effects of hydrostatic pressure on the low-K m GTPase in brain membranes from two congeneric marine fishes

Cited by 13 publications

References 35 publications

Hydrostatic Pressure Alters the Time Course of GTP[S] Binding to G Proteins in Brain Membranes from Two Congeneric Marine Fishes

Hydrostatic Pressure Alters the Time Course of GTP[S] Binding to G Proteins in Brain Membranes from Two Congeneric Marine Fishes

Co-evolution of proteins and solutions: protein adaptation versus cytoprotective micromolecules and their roles in marine organisms

Biochemical and pharmacological characterization of adenosine A1 receptors in eel (Anguilla anguilla) brain

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