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Durand A, Maillard F, Foulon J, Chalot M. Interactions between Hg and soil microbes: microbial diversity and mechanisms, with an emphasis on fungal processes. Appl Microbiol Biotechnol 2020; 104:9855-9876. [PMID: 33043392 DOI: 10.1007/s00253-020-10795-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/06/2020] [Accepted: 07/21/2020] [Indexed: 11/25/2022]
Abstract
Mercury (Hg) is a highly toxic metal with no known biological function, and it can be highly bioavailable in terrestrial ecosystems. Although fungi are important contributors to a number of soil processes including plant nutrient uptake and decomposition, little is known about the effect of Hg on fungi. Fungi accumulate the largest amount of Hg and are the organisms capable of the highest bioaccumulation of Hg. While referring to detailed mechanisms in bacteria, this mini-review emphasizes the progress made recently on this topic and represents the first step towards a better understanding of the mechanisms underlying Hg tolerance and accumulation in fungal species and hence on the role of fungi within the Hg cycle at Hg-contaminated sites. KEY POINTS: • The fungal communities are more resilient than bacterial communities to Hg exposure. • The exposure to Hg is a threat to microbial soil functions involved in both C and nutrient cycles. • Fungal (hyper)accumulation of Hg may be important for the Hg cycle in terrestrial environments. • Understanding Hg tolerance and accumulation by fungi may lead to new remediation biotechnologies.
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Affiliation(s)
- Alexis Durand
- Laboratoire Chrono-Environnement, UMR 6249, Université de Bourgogne Franche-Comté, Pôle Universitaire du Pays de Montbéliard, 4 place Tharradin, BP 71427, 25211, Montbéliard, France
- Laboratoire Sols et Environnement, UMR 1120, Université de Lorraine - INRAE, 2 avenue de la Forêt de Haye BP 20 163, 54505, Vandœuvre-lès-Nancy, France
| | - François Maillard
- Laboratoire Chrono-Environnement, UMR 6249, Université de Bourgogne Franche-Comté, Pôle Universitaire du Pays de Montbéliard, 4 place Tharradin, BP 71427, 25211, Montbéliard, France
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Julie Foulon
- Laboratoire Chrono-Environnement, UMR 6249, Université de Bourgogne Franche-Comté, Pôle Universitaire du Pays de Montbéliard, 4 place Tharradin, BP 71427, 25211, Montbéliard, France
- Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, C.P. 3300, Rimouski, QC, G5L 3A1, Canada
| | - Michel Chalot
- Laboratoire Chrono-Environnement, UMR 6249, Université de Bourgogne Franche-Comté, Pôle Universitaire du Pays de Montbéliard, 4 place Tharradin, BP 71427, 25211, Montbéliard, France.
- Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506, Vandoeuvre-les-Nancy, France.
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Csanády L, Nairn AC, Gadsby DC. Thermodynamics of CFTR channel gating: a spreading conformational change initiates an irreversible gating cycle. ACTA ACUST UNITED AC 2006; 128:523-33. [PMID: 17043148 PMCID: PMC2151586 DOI: 10.1085/jgp.200609558] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
CFTR is the only ABC (ATP-binding cassette) ATPase known to be an ion channel. Studies of CFTR channel function, feasible with single-molecule resolution, therefore provide a unique glimpse of ABC transporter mechanism. CFTR channel opening and closing (after regulatory-domain phosphorylation) follows an irreversible cycle, driven by ATP binding/hydrolysis at the nucleotide-binding domains (NBD1, NBD2). Recent work suggests that formation of an NBD1/NBD2 dimer drives channel opening, and disruption of the dimer after ATP hydrolysis drives closure, but how NBD events are translated into gate movements is unclear. To elucidate conformational properties of channels on their way to opening or closing, we performed non-equilibrium thermodynamic analysis. Human CFTR channel currents were recorded at temperatures from 15 to 35°C in inside-out patches excised from Xenopus oocytes. Activation enthalpies(ΔH‡) were determined from Eyring plots. ΔH‡ was 117 ± 6 and 69 ± 4 kJ/mol, respectively, for opening and closure of partially phosphorylated, and 96 ± 6 and 73 ± 5 kJ/mol for opening and closure of highly phosphorylated wild-type (WT) channels. ΔH‡ for reversal of the channel opening step, estimated from closure of ATP hydrolysis–deficient NBD2 mutant K1250R and K1250A channels, and from unlocking of WT channels locked open with ATP+AMPPNP, was 43 ± 2, 39 ± 4, and 37 ± 6 kJ/mol, respectively. Calculated upper estimates of activation free energies yielded minimum estimates of activation entropies (ΔS‡), allowing reconstruction of the thermodynamic profile of gating, which was qualitatively similar for partially and highly phosphorylated CFTR. ΔS‡ appears large for opening but small for normal closure. The large ΔH‡ and ΔS‡ (TΔS‡ ≥ 41 kJ/mol) for opening suggest that the transition state is a strained channel molecule in which the NBDs have already dimerized, while the pore is still closed. The small ΔS‡ for normal closure is appropriate for cleavage of a single bond (ATP's beta-gamma phosphate bond), and suggests that this transition state does not require large-scale protein motion and hence precedes rehydration (disruption) of the dimer interface.
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Affiliation(s)
- László Csanády
- Department of Medical Biochemistry, Semmelweis University, 1088 Budapest, Hungary.
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Farrell AD, Ougham HJ, Tomos AD. The effect of gibberellic acid on the response of leaf extension to low temperature. PLANT, CELL & ENVIRONMENT 2006; 29:1329-37. [PMID: 17080954 DOI: 10.1111/j.1365-3040.2006.01513.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The effect of cooling on leaf extension rate (LER) and on relative elemental growth rate (REGR) was measured in both gibberellic acid (GA)-responsive dwarf barley and in the same barley variety treated with GA. Seedlings were maintained at 20 degrees C while their leaf extension zone (LEZ) temperature was reduced either in steps to -6 degrees C in short-term cooling experiments, or to 10 degrees C for 48 h in long-term cooling experiments. Short-term cooling resulted in a biphasic response in LER, with a clear inflection point identified. Below this point, the activation energy for leaf extension becomes higher. The short-term response of LER to cooling was altered by the application of GA, which resulted in a lower base temperature (Tb), inflection point temperature and activation energy for leaf extension. Both GA-treated and untreated seedlings were less sensitive to cooling maintained for a prolonged period, with LER making a partial recover over the initial 5 h. Although long-term cooling reduced maximum REGR, it resulted in a longer LEZ and an increase in the length of mature interstomatal cells in GA-treated and untreated seedlings. These changes in overall physiology appear to enhance the ability of the leaves to continue expansion at suboptimal temperatures. In both GA-treated and cold-acclimated tissue, the occurrence of a longer LEZ was associated with a lower temperature sensitivity in LER.
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Affiliation(s)
- A D Farrell
- School of Biological Science, University of Wales Bangor, Bangor, Gwynedd, LL57 2UW UK
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TU SHUI, PATTERSON DEIDRE, BRAUER DAVID, HSU ANFEI. ANTIMYCIN A INHIBITION OF PROTON PUMPING ASSOCIATED WITH ROOT PLASMA MEMBRANE H+-ATPASE. J Food Biochem 1997. [DOI: 10.1111/j.1745-4514.1997.tb00213.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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HSU ANFEI, LUM CHARLOTTE, TU SHUI. THE EFFECT OF TRINITROPHENYL NUCLEOTIDE DERIVATIVES ON THE ADENOSINE TRIPHOSPHATASE ACTIVITIES IN MAIZE TONOPLAST VESICLES. J Food Biochem 1996. [DOI: 10.1111/j.1745-4514.1996.tb00565.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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