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Humphreys JM, Teixeira LR, Akella R, He H, Kannangara AR, Sekulski K, Pleinis J, Liwocha J, Jiou J, Servage KA, Orth K, Joachimiak L, Rizo J, Cobb MH, Brautigam CA, Rodan AR, Goldsmith EJ. Hydrostatic Pressure Sensing by WNK kinases. Mol Biol Cell 2023; 34:ar109. [PMID: 37585288 PMCID: PMC10559305 DOI: 10.1091/mbc.e23-03-0113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 08/10/2023] [Accepted: 08/10/2023] [Indexed: 08/18/2023] Open
Abstract
Previous study has demonstrated that the WNK kinases 1 and 3 are direct osmosensors consistent with their established role in cell-volume control. WNK kinases may also be regulated by hydrostatic pressure. Hydrostatic pressure applied to cells in culture with N2 gas or to Drosophila Malpighian tubules by centrifugation induces phosphorylation of downstream effectors of endogenous WNKs. In vitro, the autophosphorylation and activity of the unphosphorylated kinase domain of WNK3 (uWNK3) is enhanced to a lesser extent than in cells by 190 kPa applied with N2 gas. Hydrostatic pressure measurably alters the structure of uWNK3. Data from size exclusion chromatography in line with multi-angle light scattering (SEC-MALS), SEC alone at different back pressures, analytical ultracentrifugation (AUC), NMR, and chemical crosslinking indicate a change in oligomeric structure in the presence of hydrostatic pressure from a WNK3 dimer to a monomer. The effects on the structure are related to those seen with osmolytes. Potential mechanisms of hydrostatic pressure activation of uWNK3 and the relationships of pressure activation to WNK osmosensing are discussed.
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Affiliation(s)
- John M. Humphreys
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Liliana R. Teixeira
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Radha Akella
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Haixia He
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Ashari R. Kannangara
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kamil Sekulski
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - John Pleinis
- Department of Internal Medicine, Division of Nephrology and Hypertension and Department of Human Genetics, University of Utah, Salt Lake City UT 84112
| | - Joanna Liwocha
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jenny Jiou
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kelly A. Servage
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lukasz Joachimiak
- Center for Alzheimer’s and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Josep Rizo
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Melanie H. Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Chad A. Brautigam
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Aylin R. Rodan
- Department of Internal Medicine, Division of Nephrology and Hypertension and Department of Human Genetics, University of Utah, Salt Lake City UT 84112
| | - Elizabeth J. Goldsmith
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
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Džupponová V, Tomášková N, Antošová A, Sedlák E, Žoldák G. Salt-Specific Suppression of the Cold Denaturation of Thermophilic Multidomain Initiation Factor 2. Int J Mol Sci 2023; 24:ijms24076787. [PMID: 37047761 PMCID: PMC10094840 DOI: 10.3390/ijms24076787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/30/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023] Open
Abstract
Thermophilic proteins and enzymes are attractive for use in industrial applications due to their resistance against heat and denaturants. Here, we report on a thermophilic protein that is stable at high temperatures (Ttrs, hot 67 °C) but undergoes significant unfolding at room temperature due to cold denaturation. Little is known about the cold denaturation of thermophilic proteins, although it can significantly limit their applications. We investigated the cold denaturation of thermophilic multidomain protein translation initiation factor 2 (IF2) from Thermus thermophilus. IF2 is a GTPase that binds to ribosomal subunits and initiator fMet-tRNAfMet during the initiation of protein biosynthesis. In the presence of 9 M urea, measurements in the far-UV region by circular dichroism were used to capture details about the secondary structure of full-length IF2 protein and its domains during cold and hot denaturation. Cold denaturation can be suppressed by salt, depending on the type, due to the decreased heat capacity. Thermodynamic analysis and mathematical modeling of the denaturation process showed that salts reduce the cooperativity of denaturation of the IF2 domains, which might be associated with the high frustration between domains. This characteristic of high interdomain frustration may be the key to satisfying numerous diverse contacts with ribosomal subunits, translation factors, and tRNA.
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Affiliation(s)
- Veronika Džupponová
- Department of Biophysics, Faculty of Science, P. J. Šafárik University, Jesenna 5, 04001 Košice, Slovakia
| | - Nataša Tomášková
- Department of Biochemistry, Faculty of Science, P. J. Šafárik University in Košice, Moyzesova 11, 04001 Košice, Slovakia
| | - Andrea Antošová
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovakia
| | - Erik Sedlák
- Department of Biochemistry, Faculty of Science, P. J. Šafárik University in Košice, Moyzesova 11, 04001 Košice, Slovakia
- Center for Interdisciplinary Biosciences, Technology and Innovation Park P.J. Šafárik University, Trieda SNP 1, 04011 Košice, Slovakia
| | - Gabriel Žoldák
- Center for Interdisciplinary Biosciences, Technology and Innovation Park P.J. Šafárik University, Trieda SNP 1, 04011 Košice, Slovakia
- Center for Interdisciplinary Biosciences, Cassovia New Industry Cluster, Trieda SNP 1, 04011 Košice, Slovakia
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Eaton AK, Stewart RC. Kinetics of ATP and TNP-ATP binding to the active site of CheA from Thermotoga maritima. Biochemistry 2010; 49:5799-809. [PMID: 20565117 DOI: 10.1021/bi100721b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanism of nucleotide binding to the active site of Thermotoga maritima CheA was investigated using stopped-flow fluorescence experiments that monitored binding of ATP and TNP-ATP to the catalytic domain (P4) of CheA that had been engineered to include a tryptophan residue as a fluorescent reporter group at the active site (P4(F487W)). Rapid decreases in protein intrinsic fluorescence and increases in TNP-ATP fluorescence were observed during binding reactions, and time courses were analyzed to define the kinetic mechanisms for ATP and TNP-ATP binding. This analysis indicated that binding of ATP(Mg(2+)) to P4(F487W) involves a single reversible step with a k(on) of 0.92 +/- 0.09 microM(-1) s(-1), a k(off) of 1.9 +/- 0.4 s(-1), and a K(d) of 1.5-2.1 microM (all values determined at 4 degrees C). Binding of TNP-ATP(Mg(2+)) to P4(F487W) involves a more complicated mechanism, requiring at least three sequential steps. Computer simulations and nonlinear regression analysis were used to estimate the rate constants of the forward and reverse reactions for each of the three steps in the reaction scheme [Formula: see text] Similar analysis indicated that an alternative reaction scheme, involving a rate-limiting conformational change in P4 prior to TNP-ATP binding, did an equally good job of accounting for all of the kinetics results:[Formula: see text] In both models, steps 2 and 3 have slow reversal rates that contribute to the high affinity of the active site for TNP-ATP (K(d) = 0.015 microM). These results highlight the dramatic effect of the TNP moieties on CheA-nucleotide interactions, and they provide the first detailed information about the kinetic mechanism underlying interaction of a protein histidine kinase with this tight-binding inhibitor.
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Affiliation(s)
- Anna K Eaton
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA
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