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Meng X, Liu X, Bao Y, Luo T, Wang J. Effect of citric acid on cell membrane structure and function of Issatchenkia terricola WJL-G4. J Appl Microbiol 2024; 135:lxae057. [PMID: 38449343 DOI: 10.1093/jambio/lxae057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 02/17/2024] [Accepted: 03/05/2024] [Indexed: 03/08/2024]
Abstract
AIMS This study aimed to investigate the changes of cell membrane structure and function of Issatchenkia terricola under citric acid by performing physiological analysis. METHODS AND RESULTS The membrane integrity, surface hydrophobicity, structure, fluidity, apoptosis, and fatty acid methyl esters composition of I. terricola WJL-G4 cells were determined by propidium iodide staining, microbial adhesion to hydrocarbon test, transmission electron microscopy analysis, fluorescence anisotropy, flow cytometry, and gas chromatography-mass, respectively. The results showed that with the increasing of citric acid concentrations, the cell vitality, membrane integrity, and fluidity of I. terricola reduced; meanwhile, apoptosis rate, membrane permeable, hydrophobicity, and ergosterol contents augmented significantly. Compared to control, the activities of Na+, K+-ATPase, and Ca2+, Mg2+-ATPase increased by 3.73-fold and 6.70-fold, respectively, when citric acid concentration increased to 20 g l-1. The cells cracked and their cytoplasm effused when the citric acid concentration reached 80 g l-1. CONCLUSIONS I. terricola could successfully adjust its membrane structure and function below 60 g l-1 of citric acid. However, for citric acid concentrations above 80 g l-1, its structure and function were dramatically changed, which might result in reduced functionality.
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Affiliation(s)
- Xiangfeng Meng
- College of Life Science, Northeast Forestry University, No. 26, Hexing St., Harbin 150040, China
| | - Xinyi Liu
- College of Life Science, Northeast Forestry University, No. 26, Hexing St., Harbin 150040, China
| | - Yihong Bao
- College of Life Science, Northeast Forestry University, No. 26, Hexing St., Harbin 150040, China
- Key Laboratory of Forest Food Resources Utilization of Heilongjiang Province, No. 26, Hexing St., Harbin 150040, China
| | - Ting Luo
- State Key Laboratory of Food Science and Technology, Nanchang University, No. 999, Xuefu St., Nanchang 330047, China
| | - Jinling Wang
- College of Life Science, Northeast Forestry University, No. 26, Hexing St., Harbin 150040, China
- Key Laboratory of Forest Food Resources Utilization of Heilongjiang Province, No. 26, Hexing St., Harbin 150040, China
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2
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Abstract
Bacteria and Eukarya organize their plasma membrane spatially into domains of distinct functions. Due to the uniqueness of their lipids, membrane functionalization in Archaea remains a debated area. A novel membrane ultrastructure predicts that monolayer and bilayer domains would be laterally segregated in the hyperthermophilic archaeon Thermococcus barophilus. With very different physico-chemical parameters of the mono- and bilayer, each domain type would thus allow the docking of different membrane proteins and express different biological functions in the membrane. To estimate the ubiquity of this putative membrane ultrastructure in and out of the order Thermococcales, we re-analyzed the core lipid composition of all the Thermococcales type species and collected all the literature data available for isolated archaea. We show that all species of Thermococcales synthesize a mixture of diether bilayer forming and tetraether monolayer forming lipids, in various ratio from 10 to 80% diether in Pyrococcus horikoshii and Thermococcus gorgonarius, respectively. Since the domain formation prediction rests only on the coexistence of di- and tetraether lipids, we show that all Thermococcales have the ability for domain formation, i.e., differential functionalization of their membrane. Extrapolating this view to the whole Archaea domain, we show that almost all archaea also have the ability to synthesize di- and tetraether lipids, which supports the view that functionalized membrane domains may be shared between all Archaea. Hence domain formation and membrane compartmentalization may have predated the separation of the three domains of life and be essential for the cell cycle.
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Affiliation(s)
- Maxime Tourte
- Université de Lyon, INSA Lyon, CNRS, MAP UMR 5240, Villeurbanne, France
| | - Philippe Schaeffer
- Université de Strasbourg-CNRS, UMR 7177, Laboratoire de Biogéochimie Moléculaire, Strasbourg, France
| | - Vincent Grossi
- Université de Lyon, ENS Lyon, CNRS, Laboratoire de Géologie de Lyon, UMR 5276, Villeurbanne, France
| | - Phil M. Oger
- Université de Lyon, INSA Lyon, CNRS, MAP UMR 5240, Villeurbanne, France
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3
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Roche-Hakansson H, Vansarla G, Marks LR, Hakansson AP. The human milk protein-lipid complex HAMLET disrupts glycolysis and induces death in Streptococcus pneumoniae. J Biol Chem 2019; 294:19511-19522. [PMID: 31694917 DOI: 10.1074/jbc.ra119.009930] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 10/29/2019] [Indexed: 12/25/2022] Open
Abstract
HAMLET is a complex of human α-lactalbumin (ALA) and oleic acid and kills several Gram-positive bacteria by a mechanism that bears resemblance to apoptosis in eukaryotic cells. To identify HAMLET's bacterial targets, here we used Streptococcus pneumoniae as a model organism and employed a proteomic approach that identified several potential candidates. Two of these targets were the glycolytic enzymes fructose bisphosphate aldolase (FBPA) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Treatment of pneumococci with HAMLET immediately inhibited their ATP and lactate production, suggesting that HAMLET inhibits glycolysis. This observation was supported by experiments with recombinant bacterial enzymes, along with biochemical and bacterial viability assays, indicating that HAMLET's activity is partially inhibited by high glucose-mediated stimulation of glycolysis but enhanced in the presence of the glycolysis inhibitor 2-deoxyglucose. Both HAMLET and ALA bound directly to each glycolytic enzyme in solution and solid-phase assays and effectively inhibited their enzymatic activities. In contrast, oleic acid alone had little to no inhibitory activity. However, ALA alone also exhibited no bactericidal activity and did not block glycolysis in whole cells, suggesting a role for the lipid moiety in the internalization of HAMLET into the bacterial cells to reach its target(s). This was verified by inhibition of enzyme activity in whole cells after HAMLET but not ALA exposure. The results of this study suggest that part of HAMLET's antibacterial activity relates to its ability to target and inhibit glycolytic enzymes, providing an example of a natural antimicrobial agent that specifically targets glycolysis.
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Affiliation(s)
- Hazeline Roche-Hakansson
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York 14203
| | - Goutham Vansarla
- Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University, SE-21428 Malmö, Sweden
| | - Laura R Marks
- Department of Medicine, Barnes-Jewish Hospital, Washington University, St. Louis, Missouri 63110
| | - Anders P Hakansson
- Division of Experimental Infection Medicine, Department of Translational Medicine, Lund University, SE-21428 Malmö, Sweden
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4
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Nintemann SJ, Palmgren M, López-Marqués RL. Catch You on the Flip Side: A Critical Review of Flippase Mutant Phenotypes. Trends Plant Sci 2019; 24:468-478. [PMID: 30885637 DOI: 10.1016/j.tplants.2019.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/24/2019] [Accepted: 02/04/2019] [Indexed: 05/05/2023]
Abstract
Lipid flippases are integral membrane proteins that use ATP hydrolysis to power the generation of phospholipid asymmetry between the two leaflets of biological membranes, a process essential for cell survival. Although the first report of a plant lipid flippase was published in 2000, progress in the field has been slow, partially due to the high level of redundancy in this gene family. However, recently an increasing number of reports have examined the physiological function of lipid flippases, mainly in Arabidopsis thaliana. In this review we aim to summarize recent findings on the physiological relevance of lipid flippases in plant adaptation to a changing environment and caution against misinterpretation of pleiotropic effects in genetic studies of flippases.
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Affiliation(s)
- Sebastian J Nintemann
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Rosa Laura López-Marqués
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; https://plen.ku.dk/english/research/transport_biology/blf/.
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5
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Shen C, Liu Y, Yu H, Gulbranson DR, Kogut I, Bilousova G, Zhang C, Stowell MHB, Shen J. The N-peptide-binding mode is critical to Munc18-1 function in synaptic exocytosis. J Biol Chem 2018; 293:18309-18317. [PMID: 30275014 DOI: 10.1074/jbc.ra118.005254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/25/2018] [Indexed: 01/09/2023] Open
Abstract
Sec1/Munc18 (SM) proteins promote intracellular vesicle fusion by binding to N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). A key SNARE-binding mode of SM proteins involves the N-terminal peptide (N-peptide) motif of syntaxin, a SNARE subunit localized to the target membrane. In in vitro membrane fusion assays, inhibition of N-peptide motif binding previously has been shown to abrogate the stimulatory function of Munc18-1, a SM protein involved in synaptic exocytosis in neurons. The physiological role of the N-peptide-binding mode, however, remains unclear. In this work, we addressed this key question using a "clogged" Munc18-1 protein, in which an ectopic copy of the syntaxin N-peptide motif was directly fused to Munc18-1. We found that the ectopic N-peptide motif blocks the N-peptide-binding pocket of Munc18-1, preventing the latter from binding to the native N-peptide motif on syntaxin-1. In a reconstituted system, we observed that clogged Munc18-1 is defective in promoting SNARE zippering. When introduced into induced neuronal cells (iN cells) derived from human pluripotent stem cells, clogged Munc18-1 failed to mediate synaptic exocytosis. As a result, both spontaneous and evoked synaptic transmission was abolished. These genetic findings provide direct evidence for the crucial role of the N-peptide-binding mode of Munc18-1 in synaptic exocytosis. We suggest that clogged SM proteins will also be instrumental in defining the physiological roles of the N-peptide-binding mode in other vesicle-fusion pathways.
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Affiliation(s)
- Chong Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Yinghui Liu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,; the Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Haijia Yu
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,; the Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China,.
| | - Daniel R Gulbranson
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Igor Kogut
- the Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Ganna Bilousova
- the Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, and
| | - Chen Zhang
- the School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
| | - Michael H B Stowell
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Jingshi Shen
- From the Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309,.
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6
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Bourgoint C, Rispal D, Berti M, Filipuzzi I, Helliwell SB, Prouteau M, Loewith R. Target of rapamycin complex 2-dependent phosphorylation of the coat protein Pan1 by Akl1 controls endocytosis dynamics in Saccharomyces cerevisiae. J Biol Chem 2018; 293:12043-12053. [PMID: 29895620 PMCID: PMC6078453 DOI: 10.1074/jbc.ra117.001615] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/04/2018] [Indexed: 12/31/2022] Open
Abstract
Target of rapamycin complex 2 (TORC2) is a widely conserved serine/threonine protein kinase. In the yeast Saccharomyces cerevisiae, TORC2 is essential, playing a key role in plasma membrane homeostasis. In this role, TORC2 regulates diverse processes, including sphingolipid synthesis, glycerol production and efflux, polarization of the actin cytoskeleton, and endocytosis. The major direct substrate of TORC2 is the AGC-family kinase Ypk1. Ypk1 connects TORC2 signaling to actin polarization and to endocytosis via the flippase kinases Fpk1 and Fpk2. Here, we report that Fpk1 mediates TORC2 signaling to control actin polarization, but not endocytosis, via aminophospholipid flippases. To search for specific targets of these flippase kinases, we exploited the fact that Fpk1 prefers to phosphorylate Ser residues within the sequence RXS(L/Y)(D/E), which is present ∼90 times in the yeast proteome. We observed that 25 of these sequences are phosphorylated by Fpk1 in vitro We focused on one sequence hit, the Ark/Prk-family kinase Akl1, as this kinase previously has been implicated in endocytosis. Using a potent ATP-competitive small molecule, CMB4563, to preferentially inhibit TORC2, we found that Fpk1-mediated Akl1 phosphorylation inhibits Akl1 activity, which, in turn, reduces phosphorylation of Pan1 and of other endocytic coat proteins and ultimately contributes to a slowing of endocytosis kinetics. These results indicate that the regulation of actin polarization and endocytosis downstream of TORC2 is signaled through separate pathways that bifurcate at the level of the flippase kinases.
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Affiliation(s)
- Clélia Bourgoint
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Delphine Rispal
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Marina Berti
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Ireos Filipuzzi
- Novartis Institutes for Biomedical Research, Novartis Campus, 4056 Basel, Switzerland
| | - Stephen B Helliwell
- Novartis Institutes for Biomedical Research, Novartis Campus, 4056 Basel, Switzerland
| | - Manoël Prouteau
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland.
| | - Robbie Loewith
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), National Center for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland.
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7
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Aziz Q, Finlay M, Montaigne D, Ojake L, Li Y, Anderson N, Ludwig A, Tinker A. ATP-sensitive potassium channels in the sinoatrial node contribute to heart rate control and adaptation to hypoxia. J Biol Chem 2018; 293:8912-8921. [PMID: 29666184 DOI: 10.1074/jbc.ra118.002775] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/16/2018] [Indexed: 11/06/2022] Open
Abstract
ATP-sensitive potassium channels (KATP) contribute to membrane currents in many tissues, are responsive to intracellular metabolism, and open as ATP falls and ADP rises. KATP channels are widely distributed in tissues and are prominently expressed in the heart. They have generally been observed in ventricular tissue, but they are also expressed in the atria and conduction tissues. In this study, we focused on the contribution and role of the inwardly rectifying KATP channel subunit, Kir6.1, in the sinoatrial node (SAN). To develop a murine, conduction-specific Kir6.1 KO model, we selectively deleted Kir6.1 in the conduction system in adult mice (cKO). Electrophysiological data in single SAN cells indicated that Kir6.1 underlies a KATP current in a significant proportion of cells and influences early repolarization during pacemaking, resulting in prolonged cycle length. Implanted telemetry probes to measure heart rate and electrocardiographic characteristics revealed that the cKO mice have a slow heart rate, with episodes of sinus arrest in some mice. The PR interval (time between the onset of the P wave to the beginning of QRS complex) was increased, suggesting effects on the atrioventricular node. Ex vivo studies of whole heart or dissected heart regions disclosed impaired adaptive responses of the SAN to hypoxia, and this may have had long-term pathological consequences in the cKO mice. In conclusion, Kir6.1-containing KATP channels in the SAN have a role in excitability, heart rate control, and the electrophysiological adaptation of the SAN to hypoxia.
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Affiliation(s)
- Qadeer Aziz
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Malcolm Finlay
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - David Montaigne
- the Department of Clinical Physiology & Echocardiography, CHU Lille and the University of Lille, EGID, INSERM UMR1011, F-59000 Lille, France
| | - Leona Ojake
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Yiwen Li
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Naomi Anderson
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom
| | - Andreas Ludwig
- the Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Erlangen-Nürnberg, 91054 Erlangen, Germany, and
| | - Andrew Tinker
- From the Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, United Kingdom,
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8
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Lin X, Qi Y, Yan D, Liu H, Chen X, Liu L. CgMED3 Changes Membrane Sterol Composition To Help Candida glabrata Tolerate Low-pH Stress. Appl Environ Microbiol 2017; 83:e00972-17. [PMID: 28667115 DOI: 10.1128/AEM.00972-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 06/23/2017] [Indexed: 12/11/2022] Open
Abstract
Candida glabrata is a promising microorganism for organic acid production. The present study aimed to investigate the role of C. glabrata Mediator complex subunit 3 (CgMed3p) in protecting C. glabrata under low-pH conditions. To this end, genes CgMED3A and CgMED3B were deleted, resulting in the double-deletion Cgmed3ABΔ strain. The final biomass and cell viability levels of Cgmed3ABΔ decreased by 64.5% and 35.8%, respectively, compared to the wild-type strain results at pH 2.0. In addition, lack of CgMed3ABp resulted in selective repression of a subset of genes in the lipid biosynthesis and metabolism pathways. Furthermore, C18:1, lanosterol, zymosterol, fecosterol, and ergosterol were 13.2%, 80.4%, 40.4%, 78.1%, and 70.4% less abundant, respectively, in the Cgmed3ABΔ strain. In contrast, the concentration of squalene increased by about 44.6-fold. As a result, membrane integrity, rigidity, and H+-ATPase activity in the Cgmed3ABΔ strain were reduced by 62.7%, 13.0%, and 50.3%, respectively. In contrast, overexpression of CgMED3AB increased the levels of C18:0, C18:1, and ergosterol by 113.2%, 5.9%, and 26.4%, respectively. Moreover, compared to the wild-type results, dry cell weight and pyruvate production increased, irrespective of pH buffering. These results suggest that CgMED3AB regulates membrane composition, which in turn enables cells to tolerate low-pH stress. We propose that regulation of CgMed3ABp may provide a novel strategy for enhancing low-pH tolerance and increasing organic acid production by C. glabrataIMPORTANCE The objective of this study was to investigate the role of Candida glabrata Mediator complex subunit 3 (CgMed3ABp) and its regulation of gene expression at low pH in C. glabrata We found that CgMed3ABp was critical for cellular survival and pyruvate production during low-pH stress. Measures of the levels of plasma membrane fatty acids and sterol composition indicated that CgMed3ABp could play an important role in regulating homeostasis in C. glabrata We propose that controlling membrane lipid composition may enhance the robustness of C. glabrata for the production of organic acids.
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Seydlova G, Beranova J, Bibova I, Dienstbier A, Drzmisek J, Masin J, Fiser R, Konopasek I, Vecerek B. The extent of the temperature-induced membrane remodeling in two closely related Bordetella species reflects their adaptation to diverse environmental niches. J Biol Chem 2017; 292:8048-8058. [PMID: 28348085 DOI: 10.1074/jbc.m117.781559] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/23/2017] [Indexed: 01/06/2023] Open
Abstract
Changes in environmental temperature represent one of the major stresses faced by microorganisms as they affect the function of the cytoplasmic membrane. In this study, we have analyzed the thermal adaptation in two closely related respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica Although B. pertussis represents a pathogen strictly adapted to the human body temperature, B. bronchiseptica causes infection in a broad range of animals and survives also outside of the host. We applied GC-MS to determine the fatty acids of both Bordetella species grown at different temperatures and analyzed the membrane fluidity by fluorescence anisotropy measurement. In parallel, we also monitored the effect of growth temperature changes on the expression and production of several virulence factors. In response to low temperatures, B. pertussis adapted its fatty acid composition and membrane fluidity to a considerably lesser extent when compared with B. bronchiseptica Remarkably, B. pertussis maintained the production of virulence factors at 24 °C, whereas B. bronchiseptica cells resumed the production only upon temperature upshift to 37 °C. This growth temperature-associated differential modulation of virulence factor production was linked to the phosphorylation state of transcriptional regulator BvgA. The observed differences in low-temperature adaptation between B. pertussis and B. bronchiseptica may result from selective adaptation of B. pertussis to the human host. We propose that the reduced plasticity of the B. pertussis membranes ensures sustained production of virulence factors at suboptimal temperatures and may play an important role in the transmission of the disease.
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Affiliation(s)
- Gabriela Seydlova
- From the Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 5, 12843 Prague, Czech Republic
| | - Jana Beranova
- From the Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 5, 12843 Prague, Czech Republic
| | - Ilona Bibova
- the Laboratories of Post-transcriptional Control of Gene Expression and
| | - Ana Dienstbier
- the Laboratories of Post-transcriptional Control of Gene Expression and
| | - Jakub Drzmisek
- the Laboratories of Post-transcriptional Control of Gene Expression and
| | - Jiri Masin
- Molecular Biology of Bacterial Pathogens, Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague, Czech Republic
| | - Radovan Fiser
- From the Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 5, 12843 Prague, Czech Republic
| | - Ivo Konopasek
- From the Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 5, 12843 Prague, Czech Republic
| | - Branislav Vecerek
- the Laboratories of Post-transcriptional Control of Gene Expression and
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Yamamoto H, Tobisawa Y, Inubushi T, Irie F, Ohyama C, Yamaguchi Y. A mammalian homolog of the zebrafish transmembrane protein 2 (TMEM2) is the long-sought-after cell-surface hyaluronidase. J Biol Chem 2017; 292:7304-7313. [PMID: 28246172 DOI: 10.1074/jbc.m116.770149] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Revised: 02/27/2017] [Indexed: 12/31/2022] Open
Abstract
Hyaluronan (HA) is an extremely large polysaccharide (glycosaminoglycan) involved in many cellular functions. HA catabolism is thought to involve the initial cleavage of extracellular high-molecular-weight (HMW) HA into intermediate-size HA by an extracellular or cell-surface hyaluronidase, internalization of intermediate-size HA, and complete degradation into monosaccharides in lysosomes. Despite considerable research, the identity of the hyaluronidase responsible for the initial HA cleavage in the extracellular space remains elusive. HYAL1 and HYAL2 have properties more consistent with lysosomal hyaluronidases, whereas CEMIP/KIAA1199, a recently identified HA-binding molecule that has HA-degrading activity, requires the participation of the clathrin-coated pit pathway of live cells for HA degradation. Here we show that transmembrane protein 2 (TMEM2), a mammalian homolog of a protein playing a role in zebrafish endocardial cushion development, is a cell-surface hyaluronidase. Live immunostaining and surface biotinylation assays confirmed that mouse TMEM2 is expressed on the cell surface in a type II transmembrane topology. TMEM2 degraded HMW-HA into ∼5-kDa fragments but did not cleave chondroitin sulfate or dermatan sulfate, indicating its specificity to HA. The hyaluronidase activity of TMEM2 was Ca2+-dependent; the enzyme's pH optimum is around 6-7, and unlike CEMIP/KIAA1199, TMEM2 does not require the participation of live cells for its hyaluronidase activity. Moreover, TMEM2-expressing cells could eliminate HA immobilized on a glass surface in a contact-dependent manner. Together, these data suggest that TMEM2 is the long-sought-after hyaluronidase that cleaves extracellular HMW-HA into intermediate-size fragments before internalization and degradation in the lysosome.
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Affiliation(s)
- Hayato Yamamoto
- From the Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037 and
| | - Yuki Tobisawa
- From the Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037 and
| | - Toshihiro Inubushi
- From the Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037 and
| | - Fumitoshi Irie
- From the Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037 and
| | - Chikara Ohyama
- the Department of Urology, Hirosaki University Graduate School of Medicine, Hirosaki 036-8562, Japan
| | - Yu Yamaguchi
- From the Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037 and
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11
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Koch S, de Wit JG, Vos I, Birkner JP, Gordiichuk P, Herrmann A, van Oijen AM, Driessen AJM. Lipids Activate SecA for High Affinity Binding to the SecYEG Complex. J Biol Chem 2016; 291:22534-22543. [PMID: 27613865 DOI: 10.1074/jbc.m116.743831] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/30/2016] [Indexed: 11/06/2022] Open
Abstract
Protein translocation across the bacterial cytoplasmic membrane is an essential process catalyzed predominantly by the Sec translocase. This system consists of the membrane-embedded protein-conducting channel SecYEG, the motor ATPase SecA, and the heterotrimeric SecDFyajC membrane protein complex. Previous studies suggest that anionic lipids are essential for SecA activity and that the N terminus of SecA is capable of penetrating the lipid bilayer. The role of lipid binding, however, has remained elusive. By employing differently sized nanodiscs reconstituted with single SecYEG complexes and comprising varying amounts of lipids, we establish that SecA gains access to the SecYEG complex via a lipid-bound intermediate state, whereas acidic phospholipids allosterically activate SecA for ATP-dependent protein translocation.
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Affiliation(s)
- Sabrina Koch
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials and
| | - Janny G de Wit
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials and
| | - Iuliia Vos
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials and
| | - Jan Peter Birkner
- the Single-molecule Biophysics, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Pavlo Gordiichuk
- the Polymer Chemistry and Bioengineering, Zernike Institute for Advanced Materials, 9747 AG, Groningen, The Netherlands, and
| | - Andreas Herrmann
- the Polymer Chemistry and Bioengineering, Zernike Institute for Advanced Materials, 9747 AG, Groningen, The Netherlands, and
| | - Antoine M van Oijen
- the Single-molecule Biophysics, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands.,the School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Arnold J M Driessen
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials and
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12
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Zhang Y, Lee KM, Kinch LN, Clark L, Grishin NV, Rosenbaum DM, Brown MS, Goldstein JL, Radhakrishnan A. Direct Demonstration That Loop1 of Scap Binds to Loop7: A CRUCIAL EVENT IN CHOLESTEROL HOMEOSTASIS. J Biol Chem 2016; 291:12888-12896. [PMID: 27068746 DOI: 10.1074/jbc.m116.729798] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 11/06/2022] Open
Abstract
Cholesterol homeostasis is mediated by Scap, a polytopic endoplasmic reticulum (ER) protein that transports sterol regulatory element-binding proteins from the ER to Golgi, where they are processed to forms that activate cholesterol synthesis. Scap has eight transmembrane helices and two large luminal loops, designated Loop1 and Loop7. We earlier provided indirect evidence that Loop1 binds to Loop7, allowing Scap to bind COPII proteins for transport in coated vesicles. When ER cholesterol rises, it binds to Loop1. We hypothesized that this causes dissociation from Loop7, abrogating COPII binding. Here we demonstrate direct binding of the two loops when expressed as isolated fragments or as a fusion protein. Expressed alone, Loop1 remained intracellular and membrane-bound. When Loop7 was co-expressed, it bound to Loop1, and the soluble complex was secreted. A Loop1-Loop7 fusion protein was also secreted, and the two loops remained bound when the linker between them was cleaved by a protease. Point mutations that disrupt the Loop1-Loop7 interaction prevented secretion of the Loop1-Loop7 fusion protein. These data provide direct documentation of intramolecular Loop1-Loop7 binding, a central event in cholesterol homeostasis.
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Affiliation(s)
| | | | - Lisa N Kinch
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | | | - Nick V Grishin
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Biophysics, and; Biochemistry and
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13
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Abstract
Oligomerization of the Ca2+ sensor, STIM1, in the endoplasmic reticulum (ER) membrane, caused by depletion of ER Ca2+ stores, results in STIM1 coupling to the plasma membrane Ca2+ channel protein, Orai1, to activate Ca2+ influx in a process known as store-operated Ca2+ entry. We use fluorimetry-based fluorescence resonance energy transfer (FRET) to monitor changes in STIM1 oligomerization in COS7 cells transfected with STIM1 constructs containing selected truncations, deletions, and point mutations, and labeled with donor and acceptor fluorescent proteins at either the luminal (N-terminal) or the cytoplasmic (C-terminal) ends. Our results with sequential truncations of STIM1 from the C-terminus support previous evidence that the CRAC activation domain (CAD/SOAR, human sequence 342–448) is an oligomer-promoting segment of STIM1, and they show that truncation just after CAD/SOAR (1–448) causes significantly elevated basal cytoplasmic Ca2+ and spontaneous STIM1 clustering. We find that a 14 amino acid sequence just C-terminal of CAD/SOAR (449–462) prevents spontaneous clustering and activation of STIM1 in COS7 cells. In response to store depletion, C-terminally labeled STIM1 without CAD/SOAR clusters together with CAD/SOAR-containing STIM1 constructs. However, these donor-acceptor pairs do not undergo a stimulated increase in FRET, exhibiting instead a decrease in FRET consistent with a stimulated conformational extension in full length STIM1. We find that the 14 amino acid sequence plays a regulatory role in this process. Overall, our FRET results provide evidence in live cells that Ca2+ store depletion stimulates a conformational extension in the cytoplasmic segment of STIM1 that accompanies its oligomerization.
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Affiliation(s)
- Marek K Korzeniowski
- Department of Chemistry and Chemical Biology Cornell University, Ithaca, NY 14853
| | - Barbara Baird
- Department of Chemistry and Chemical Biology Cornell University, Ithaca, NY 14853
| | - David Holowka
- Department of Chemistry and Chemical Biology Cornell University, Ithaca, NY 14853
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14
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Ludolphs M, Schneeberger D, Soykan T, Schäfer J, Papadopoulos T, Brose N, Schindelin H, Steinem C. Specificity of Collybistin-Phosphoinositide Interactions: IMPACT OF THE INDIVIDUAL PROTEIN DOMAINS. J Biol Chem 2015; 291:244-54. [PMID: 26546675 DOI: 10.1074/jbc.m115.673400] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Indexed: 01/01/2023] Open
Abstract
The regulatory protein collybistin (CB) recruits the receptor-scaffolding protein gephyrin to mammalian inhibitory glycinergic and GABAergic postsynaptic membranes in nerve cells. CB is tethered to the membrane via phosphoinositides. We developed an in vitro assay based on solid-supported 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membranes doped with different phosphoinositides on silicon/silicon dioxide substrates to quantify the binding of various CB2 constructs using reflectometric interference spectroscopy. Based on adsorption isotherms, we obtained dissociation constants and binding capacities of the membranes. Our results show that full-length CB2 harboring the N-terminal Src homology 3 (SH3) domain (CB2SH3+) adopts a closed and autoinhibited conformation that largely prevents membrane binding. This autoinhibition is relieved upon introduction of the W24A/E262A mutation, which conformationally "opens" CB2SH3+ and allows the pleckstrin homology domain to properly bind lipids depending on the phosphoinositide species with a preference for phosphatidylinositol 3-monophosphate and phosphatidylinositol 4-monophosphate. This type of membrane tethering under the control of the release of the SH3 domain of CB is essential for regulating gephyrin clustering.
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Affiliation(s)
- Michaela Ludolphs
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Daniela Schneeberger
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Tolga Soykan
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany, and
| | - Jonas Schäfer
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Theofilos Papadopoulos
- Universitätsmedizin Göttingen, Department of Molecular Biology, Humboldtallee 23, 37073 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany, and
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Claudia Steinem
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany,
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15
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Geng Y, Kedrov A, Caumanns JJ, Crevenna AH, Lamb DC, Beckmann R, Driessen AJM. Role of the Cytosolic Loop C2 and the C Terminus of YidC in Ribosome Binding and Insertion Activity. J Biol Chem 2015; 290:17250-61. [PMID: 26023232 DOI: 10.1074/jbc.m115.650309] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Indexed: 11/06/2022] Open
Abstract
Members of the YidC/Oxa1/Alb3 protein family mediate membrane protein insertion, and this process is initiated by the assembly of YidC·ribosome nascent chain complexes at the inner leaflet of the lipid bilayer. The positively charged C terminus of Escherichia coli YidC plays a significant role in ribosome binding but is not the sole determinant because deletion does not completely abrogate ribosome binding. The positively charged cytosolic loops C1 and C2 of YidC may provide additional docking sites. We performed systematic sequential deletions within these cytosolic domains and studied their effect on the YidC insertase activity and interaction with translation-stalled (programmed) ribosome. Deletions within loop C1 strongly affected the activity of YidC in vivo but did not influence ribosome binding or substrate insertion, whereas loop C2 appeared to be involved in ribosome binding. Combining the latter deletion with the removal of the C terminus of YidC abolished YidC-mediated insertion. We propose that these two regions play an crucial role in the formation and stabilization of an active YidC·ribosome nascent chain complex, allowing for co-translational membrane insertion, whereas loop C1 may be involved in the downstream chaperone activity of YidC or in other protein-protein interactions.
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Affiliation(s)
- Yanping Geng
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | | | - Joseph J Caumanns
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Alvaro H Crevenna
- the Physical Chemistry, Department for Chemistry, Center for Nanoscience, the NanoSystems Initiative Munich and the Center for Integrated Protein Science Munich, Ludwig-Maximilians-University, 81377 Munich, Germany
| | - Don C Lamb
- the Physical Chemistry, Department for Chemistry, Center for Nanoscience, the NanoSystems Initiative Munich and the Center for Integrated Protein Science Munich, Ludwig-Maximilians-University, 81377 Munich, Germany
| | | | - Arnold J M Driessen
- From the Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, Nijenborgh 7, 9747 AG Groningen, The Netherlands,
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16
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Zhang Z, Tang QY, Alaimo JT, Davies AG, Bettinger JC, Logothetis DE. SLO-2 isoforms with unique Ca(2+) - and voltage-dependence characteristics confer sensitivity to hypoxia in C. elegans. Channels (Austin) 2013; 7:194-205. [PMID: 23590941 DOI: 10.4161/chan.24492] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Slo channels are large conductance K (+) channels that display marked differences in their gating by intracellular ions. Among them, the Slo1 and C. elegans SLO-2 channels are gated by calcium (Ca ( 2+) ), while mammalian Slo2 channels are activated by both sodium (Na (+) ) and chloride (Cl (-) ). Here, we report that SLO-2 channels, SLO-2a and a novel N-terminal variant isoform, SLO-2b, are activated by Ca ( 2+) and voltage, but in contrast to previous reports they do not exhibit Cl (-) sensitivity. Most importantly, SLO-2 provides a unique case in the Slo family for sensing Ca ( 2+) with the high-affinity Ca ( 2+) regulatory site in the RCK1 but not the RCK2 domain, formed through interactions with residues E319 and E487 (that correspond to D362 and E535 of Slo1, respectively). The SLO-2 RCK2 domain lacks the Ca ( 2+) bowl structure and shows minimal Ca ( 2+) dependence. In addition, in contrast to SLO-1, SLO-2 loss-of-function mutants confer resistance to hypoxia in C. elegans. Thus, the C. elegans SLO-2 channels possess unique biophysical and functional properties.
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Affiliation(s)
- Zhe Zhang
- Department of Physiology and Biophysics, Virginia Commonwealth University, Medical College of Virginia Campus, Richmond, VA, USA.
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17
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Truschel ST, Zhang M, Bachert C, Macbeth MR, Linstedt AD. Allosteric regulation of GRASP protein-dependent Golgi membrane tethering by mitotic phosphorylation. J Biol Chem 2012; 287:19870-5. [PMID: 22523075 PMCID: PMC3370171 DOI: 10.1074/jbc.m111.326256] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 02/23/2012] [Indexed: 11/06/2022] Open
Abstract
Mitotic phosphorylation of the conserved GRASP domain of GRASP65 disrupts its self-association, leading to a loss of Golgi membrane tethering, cisternal unlinking, and Golgi breakdown. Recently, the structural basis of the GRASP self-interaction was determined, yet the mechanism by which phosphorylation disrupts this activity is unknown. Here, we present the crystal structure of a GRASP phosphomimic containing an aspartic acid substitution for a serine residue (Ser-189) that in GRASP65 is phosphorylated by PLK1, causing a block in membrane tethering and Golgi ribbon formation. The structure revealed a conformational change in the GRASP internal ligand that prevented its insertion into the PDZ binding pocket, and gel filtration assays showed that this phosphomimic mutant exhibited a significant reduction in dimer formation. Interestingly, the structure also revealed an apparent propagation of conformational change from the site of phosphorylation to the shifted ligand, and alanine substitution of two residues (Glu-145 and Ser-146) at penultimate positions in this chain rescued dimer formation by the phosphomimic. These data reveal the structural basis of the phosphoinhibition of GRASP-mediated membrane tethering and provide a mechanism for its allosteric regulation.
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Affiliation(s)
- Steven T. Truschel
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Ming Zhang
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Collin Bachert
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Mark R. Macbeth
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Adam D. Linstedt
- From the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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18
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Pan D, Kalfa TA, Wang D, Risinger M, Crable S, Ottlinger A, Chandra S, Mount DB, Hübner CA, Franco RS, Joiner CH. K-Cl cotransporter gene expression during human and murine erythroid differentiation. J Biol Chem 2011; 286:30492-30503. [PMID: 21733850 PMCID: PMC3162409 DOI: 10.1074/jbc.m110.206516] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 06/23/2011] [Indexed: 11/06/2022] Open
Abstract
The K-Cl cotransporter (KCC) regulates red blood cell (RBC) volume, especially in reticulocytes. Western blot analysis of RBC membranes revealed KCC1, KCC3, and KCC4 proteins in mouse and human cells, with higher levels in reticulocytes. KCC content was higher in sickle versus normal RBC, but the correlation with reticulocyte count was poor, with inter-individual variability in KCC isoform ratios. Messenger RNA for each isoform was measured by real time RT-quantitative PCR. In human reticulocytes, KCC3a mRNA levels were consistently the highest, 1-7-fold higher than KCC4, the second most abundant species. Message levels for KCC1 and KCC3b were low. The ratios of KCC RNA levels varied among individuals but were similar in sickle and normal RBC. During in vivo maturation of human erythroblasts, KCC3a RNA was expressed consistently, whereas KCC1 and KCC3b levels declined, and KCC4 message first increased and then decreased. In mouse erythroblasts, a similar pattern for KCC3 and KCC1 expression during in vivo differentiation was observed, with low KCC4 RNA throughout despite the presence of KCC4 protein in mature RBC. During differentiation of mouse erythroleukemia cells, protein levels of KCCs paralleled increasing mRNA levels. Functional properties of KCCs expressed in HEK293 cells were similar to each other and to those in human RBC. However, the anion dependence of KCC in RBC resembled most closely that of KCC3. The results suggest that KCC3 is the dominant isoform in erythrocytes, with variable expression of KCC1 and KCC4 among individuals that could result in modulation of KCC activity.
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Affiliation(s)
- Dao Pan
- Molecular and Cell Therapy Program, Division of Experimental Hematology, Cincinnati, Ohio 45229; the Departments of Pediatrics, Cincinnati, Ohio 45267.
| | - Theodosia A Kalfa
- the Departments of Pediatrics, Cincinnati, Ohio 45267; Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229
| | - Daren Wang
- Molecular and Cell Therapy Program, Division of Experimental Hematology, Cincinnati, Ohio 45229
| | - Mary Risinger
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229
| | - Scott Crable
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229
| | - Anna Ottlinger
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229
| | - Sharat Chandra
- the Departments of Pediatrics, Cincinnati, Ohio 45267; Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229
| | - David B Mount
- Renal Division, Brigham and Women's Hospital, Veterans Affairs Boston Healthcare System, Harvard Medical School, Boston, Massachusetts 02115
| | - Christian A Hübner
- Department of Clinical Chemistry, University Hospital of the Friedrich-Schiller-University, D-07747 Jena, Germany
| | - Robert S Franco
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229; Internal Medicine, University of Cincinnati School of Medicine, Cincinnati, Ohio 45267
| | - Clinton H Joiner
- the Departments of Pediatrics, Cincinnati, Ohio 45267; Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, 45229.
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19
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Xia Y, Lundbäck AK, Sahaf N, Nordlund G, Brzezinski P, Eshaghi S. Co2+ selectivity of Thermotoga maritima CorA and its inability to regulate Mg2+ homeostasis present a new class of CorA proteins. J Biol Chem 2011; 286:16525-32. [PMID: 21454699 PMCID: PMC3091257 DOI: 10.1074/jbc.m111.222166] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/19/2011] [Indexed: 01/12/2023] Open
Abstract
CorA is a family of divalent cation transporters ubiquitously present in bacteria and archaea. Although CorA can transport both Mg(2+) and Co(2+) almost equally well, its main role has been suggested to be that of primary Mg(2+) transporter of prokaryotes and hence the regulator of Mg(2+) homeostasis. The reason is that the affinity of CorA for Co(2+) is relatively low and thus considered non-physiological. Here, we show that Thermotoga maritima CorA (TmCorA) is incapable of regulating the Mg(2+) homeostasis and therefore cannot be the primary Mg(2+) transporter of T. maritima. Further, our in vivo experiments confirm that TmCorA is a highly selective Co(2+) transporter, as it selects Co(2+) over Mg(2+) at >100 times lower concentrations. In addition, we present data that show TmCorA to be extremely thermostable in the presence of Co(2+). Mg(2+) could not stabilize the protein to the same extent, even at high concentrations. We also show that addition of Co(2+), but not Mg(2+), specifically induces structural changes to the protein. Altogether, these data show that TmCorA has the role of being the transporter of Co(2+) but not Mg(2+). The physiological relevance and requirements of Co(2+) in T. maritima is discussed and highlighted. We suggest that CorA may have different roles in different organisms. Such functional diversity is presumably a reflection of minor, but important structural differences within the CorA family that regulate the gating, substrate selection, and transport.
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Affiliation(s)
- Yu Xia
- From the Biomedical Structural Biology, School of Biological Sciences, Nanyang Technological University, Singapore 138673, Singapore and
| | - Anna-Karin Lundbäck
- From the Biomedical Structural Biology, School of Biological Sciences, Nanyang Technological University, Singapore 138673, Singapore and
| | - Newsha Sahaf
- From the Biomedical Structural Biology, School of Biological Sciences, Nanyang Technological University, Singapore 138673, Singapore and
| | - Gustav Nordlund
- the Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 10691 Stockholm, Sweden
| | - Peter Brzezinski
- the Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 10691 Stockholm, Sweden
| | - Said Eshaghi
- From the Biomedical Structural Biology, School of Biological Sciences, Nanyang Technological University, Singapore 138673, Singapore and
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20
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Newton SM, Trinh V, Pi H, Klebba PE. Direct measurements of the outer membrane stage of ferric enterobactin transport: postuptake binding. J Biol Chem 2010; 285:17488-97. [PMID: 20335169 PMCID: PMC2878513 DOI: 10.1074/jbc.m109.100206] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 02/23/2010] [Indexed: 11/06/2022] Open
Abstract
When Gram-negative bacteria acquire iron, the metal crosses both the outer membrane (OM) and the inner membrane, but existing radioisotopic uptake assays only measure its passage through the latter bilayer, as the accumulation of the radionuclide in the cytoplasm. We devised a methodology that exclusively observes OM transport and used it to study the uptake of ferric enterobactin (FeEnt) by Escherichia coli FepA. This technique, called postuptake binding, revealed previously unknown aspects of TonB-dependent transport reactions. The experiments showed, for the first time, that despite the discrepancy in cell envelope concentrations of FepA and TonB ( approximately 35:1), all FepA proteins were active and equivalent in FeEnt uptake, with a maximum turnover number of approximately 5/min. FepA-mediated transport of FeEnt progressed through three distinct phases with successively decreasing rates, and from its temperature dependence, the activation energy of the OM stage was 33-35 kcal/mol. The accumulation of FeEnt in the periplasm required the binding protein and inner membrane permease components of its overall transport system; postuptake binding assays on strains devoid of FepB, FepD, or FepG did not show uptake of FeEnt through the OM. However, fluorescence labeling data implied that FepA was active in the DeltafepB strain, suggesting that FeEnt entered the periplasm but then leaked out. Further experiments confirmed this futile cycle; cells without FepB transported FeEnt across the OM, but it immediately escaped through TolC.
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Affiliation(s)
- Salete M. Newton
- From the Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019
| | - Vy Trinh
- From the Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019
| | - Hualiang Pi
- From the Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019
| | - Phillip E. Klebba
- From the Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019
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