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Michael E. Maguire, Ph.D.

Maquire

Professor of Pharmacology
Professor of Molecular Biology and Microbiology

Phone: (216) 368-6186
Fax: (216) 368-3395
E-mail: michael.maguire@case.edu
Wood W-213

Research

The research in the Maguire lab is focused on the multiple roles of Mg2+ and Mn2+ in bacterial metabolism and pathogenesis using primarily Salmonella enterica serovar Typhimurium (S. Typhimurium) as a model system.

  1. The CorA Mg2+ transporter is the primary Mg2+ uptake system of most Bacteria and Archaea. It has no homology to any other protein. We have identified features of its oligomeric structure and intramembrane residues that form an apparent Mg2+-permeable pore. Uniquely, CorA transports the charge dense Mg2+ cation without electrostatic interactions within the membrane. CorA is also a virulence factor for Salmonella typhimurium, affecting macrophage invasion and expression of a number of other genes important for virulence. Surprisingly, although S. Typhimurium has two additional Mg2+ transport systems, mutation of corA has profound metabolic defects including an inability to respire on numerous substrates including pyruvate. We are studying the role of CorA in virulence and investigation structure-function relationship of the transporter.
     
  2. The MgtA/MgtB Mg2+ transporters are regulated by Mg2+, the ligand for the phoP/phoQ signal transduction system, a system essential for virulence in Salmonella and other bacteria. The MgtC protein is also regulated by phoP/phoQ. Mutations in mgtC alter S. Typhimurium virulence. Cell biology studies and expression of mgtC in frog oocytes suggests that MgtC is injected into the macrophage cell's membrane upon S. typhimurium invasion where is interacts with and constitutively activates the macrophage Na+,K+-ATPase. This results in marked alteration of macrophage membrane potential, presumably to the bacterium's benefit. Future studies will focus on transcriptional and translational regulation of mgtC to gain insight into its function.
     
  3. The MntH Mn2+ transporter is a homolog of mammalian NRAMP proteins which confer resistance to several pathogens. Most bacterial NRAMPs (MntH) are highly se¬lective Mn2+ influx systems involved in bacterial response to reactive oxygen species and pathogenesis. The SitABCD Mn2+ transporter is and ABC class protein, operative only at alkaline pH and highly selective for Mn2+. Mutation of both MntH and SitABCD renders S. Typhimurium avirulent if and only if the host organism expresses a functional NRAMP1 transporter in macrophages. We are investigating the few known Mn2+-de¬pendent enzymes for their importance in pathogenesis. One of these enzymes is GpmM, a Mn2+-dependent phosphoglyceromutase, which catalyzes an essential step in glycolysis. S. Typhimurium, like many bacteria, possesses an additional phosphogly¬ceromutase, GpmA, that is neither homologous to GpmM nor metal dependent. The capacity of these enzymes is identical, yet their mutation has profound and distinct metabolic consequences. Mutation of GpmA has no effect on the ability to grow or respire on any carbon source, but cells lacking GpmA cannot survive in stationary phase and are very sensitive to reactive oxygen species. In contrast, cells lacking GpmM has severely impaired growth on most carbon sources but are equivalent to wild type cells for stationary phase survival.
     
  4. S. Typhimurium also expresses several hundred phosphoproteins. In virtually all cases, the role of phosphorylation is unknown. We have begun a proteomics project to catalog the "phosphoproteome" of S. Typhimurium, focusing (initially) on soluble phosphoproteins of the bacterium. In addition, the S. Typhimurium genome encodes 2 protein kinases and 2 protein phosphatases that are clear paralogs of eukaryotic kinases and phosphatases involved in signal transduction networks. We have cloned and partially characterized all 4 both enzymatically and phenotypically. All 4 are Mn2+ dependent and cannot use Mg2+. As part of the phosphoproteome project, we are identifying substrates of these enzymes and investigating the physiological role of phosphorylation.

Current Research Directions:

Role of Mg2+ and Mn2+ in S. typhimurium pathogenesis including mouse virulence studies of various mutant strains, the role of Mn2+ in response to reactive oxygen, Mg2+ regulation of virulence.

Role of Mn2+ in carbon metabolism and flux in S. Typhimurium.

Structure of CorA including x-ray crystallographic analysis of the periplasmic domains of several CorA proteins from various organisms. (In collaboration with Dr. Vivien Yee)

Electrophysiological investigation of the mechanisms of Mg2+ and Mn2+ transport by CorA and MntH, and of the properties of MgtC, after expression in Xenopus oocytes. (In collaboration with Dr. Michael Romero)

Definition of the "phosphoproteome" of S. Typhimurium.

Structure of the MgtB P-type ATPase via random and site-directed mutagenesis and purification/reconstitution.

Selected publications 2000—present:

Kehres, D.G., M.L. Zaharik, B.B. Finlay and M.E. Maguire (2000) The NRAMP Proteins of Salmonella typhimurium and Escherichia coli Are Mn2+ Selective Transporters Involved in the Response to Reactive Oxygen, Molec. Microb 36:1085-1100.

Kucharski, L.M., W.J. Lubbe and M.E. Maguire (2000) “Cation Hexaammines Are Potent and Selective Inhibitors of the CorA Magnesium Transport System,” J. Biological Chemistry 275:16767-16773.

Maguire, M.E. (2001) “Magnesium Homeostasis And Transport:  A Unique Cation Continues To Spring Surprises”, in Advances in Magnesium Research : Nutrition and Health, Y. Rayssiguier, A. Mazur and J. Durlach, Eds., John Libbey, London, pp. 3-12.  Plenary Lecture, 9th International Magnesium Conference.

Shi, L., D.G. Kehres and M.E. Maguire (2001) “The PPP family protein phosphatases PrpA and PrpB of Salmonella enterica serovar Typhimurium possess distinct biochemical properties”, J. Bacteriology 183:7053-7057.

Kehres, D.G., A. Janakiraman, J.M. Slauch and M.E. Maguire (2002) “Regulation of Salmonella enterica Serovar Typhimurium mntH Transcription by H2O2, Fe2+, and Mn, J. Bacteriology 184:3151-3158.

Kehres, D.G., and M.E. Maguire (2002) “SitABCD Is the Alkaline Manganese Transporter of Salmonella enterica serovar Typhimurium”, J. Bacteriology 184:3159-3166.

Papp, K. and M.E. Maguire (2004) “The CorA Mg2+ Transporter Does Not Transport Fe2+,” J. Bacteriology 186:7653-7658.

Zaharik, M.L. V. L. Cullen, A. M. Fung, S. J. Libby, S. Kujat-Choy, B. Coburn, D. G. Kehres, M. E. Maguire, F. C. Fang, and B. B. Finlay (2004) The Salmonella enterica serovar Typhimurium divalent cation transport systems MntH and SitABCD are essential for virulence in an Nramp1G169 murine typhoid model, Infection and Immunity 72:5522-5.

Lunin, V.L., E. Dobrovetsky, G. Khutoreskaya, R. Zhang, A. Joachimiak, A. Bochkarev, M.E. Maguire, A.M. Edwards, C.M. Koth (2006) “Crystal Structure of the CorA Mg2+ Transporter from Thermotoga maritima,” Nature 440:833-837.

Papp-Wallace, K. and M.E. Maguire (2006) “Manganese Transport and the Role of Manganese in Virulence,” Ann. Rev. Microbiol. 60:187-209

Maguire, M.E. (2006) “Magnesium Transporters: Properties, Regulation and Structure”, Frontiers in Bioscience, 11:3149-3163.

Günzel, D., D.G. Kehres, L. Kucharski, M.F. Romero and M.E. Maguire (2006) “The MgtC Virulence Factor of Salmonella enterica serovar Typhimurium Activates Na+,K+-ATPase”, J. Bacteriology 188:5586-5594.

Maguire, M.E. (2006) “The Structure of CorA:  A Mg2+-Selective Channel,” Curr. Opin. Structural Biol., invited review, 16:432-438

Selected publications 1976-1999

Maguire, M.E., R.A. Wiklund, H.J. Anderson and A.G. Gilman  (1976)  "Binding of [125I]-Iodohydroxybenzylpindolol to Putative b-Adrenergic Receptors of Rat Glioma Cells and Other Cell Clones", J. Biol. Chem. 251:1221-1231.

Maguire, M.E., P.M. van Arsdale and A.G. Gilman  (1976)  "An Agonist Specific Effect of Guanine Nucleotides on Binding to the b-Adrenergic Receptor", Molec. Pharmacol. 12:335-339.

Insel, P.A., M.E. Maguire, A.G. Gilman, H.R. Bourne, P. Coffino and K.L. Melmon  (1976)  "β-Adrenergic Receptors and Adenylate Cyclase: Products of Separate Genes?", Molec. Pharmacol. 12:1062-1069.

Ross, E.M., M.E. Maguire, T.W. Sturgill, R.L. Biltonen and A.G. Gilman  (1977)  "The Relationship Between the β-Adrenergic Receptor and Adenylate Cyclase:  Studies of Ligand Binding and Enzyme Activity in Purified Membranes of S49 Lymphoma Cells", J. Biol. Chem. 252:5761-5775.

Maguire, M.E., E.M. Ross and A.G. Gilman  (1977)  "β-Adrenergic Receptor: Ligand Binding Proper­ties and the Interaction with Adenylate Cyclase", Adv. Cyclic Nucleotide Res. 8:1-83.

Bird, S.J., and M.E. Maguire  (1978)  "The Agonist-Specific Effect of Magnesium Ion on Binding by β-Adrenergic Receptors of S49 Lymphoma Cells:  Interactions of GTP and Magnesium in Adenylate Cyclase Activation", J. Biol. Chem. 253:8826-8834.

Maguire. M.E., and J.J. Erdos  (1978)  "Magnesium but not Calcium Accumulation is Inhibited by β-Adrenergic Stimulation in S49 Lymphoma Cells", J. Biol. Chem. 253:6633- 6636.

Maguire, M.E., and J.J. Erdos  (1980)  "Inhibition of Magnesium Uptake by β-Adrenergic Agonists and Prostaglandin E1 Is Not Mediated by Cyclic AMP", J. Biol. Chem. 255:1030-1035.

Erdos, J.J. and M.E. Maguire (1983) "Hormone-sensitive Magnesium Transport in Murine S49 Lymphoma Cells:  Characterization and Specificity for Magnesium", J. Physiology (London) 337:351- 371

Grubbs, R.D., S.D. Collins, and M.E. Maguire (1984) "Differential Compartmentation of Magnesium and Calcium in Murine S49 Lymphoma Cells", J. Biological Chemistry 259:12184-12192.

Hmiel, S.P., M.D. Snavely, C.G. Miller and M.E. Maguire (1986) "Magnesium Transport in Salmo­nella typhimurium: Characterization of Magnesium Influx and Cloning of a Transport Gene", J. Bacteriology 168:1444-1450.

Hmiel, S.P., Snavely, M.D., J.B. Florer, M.E. Maguire, and C.G. Miller (1989) "Mg<+ Transport in Salmonella typhimurium: Genetic Characterization and Cloning of Three Magnesium Transport Loci", J. Bacteriology 171:4742-4751.

Snavely, M.D., J.B. Florer, C.G. Miller and M.E. Maguire (1989) "Mg<+ Transport in Salmonella typhimurium: 28Mg2+ Uptake by the CorA, MgtA and MgtB Systems", J. Bacteriology 171:4761- 4766.

Maguire, M.E. (1990) "Magnesium as a Regulated and Regulatory Cation", Metal Ions in Biological Systems 26:135-153.

Snavely, M.D., C.G. Miller and M.E. Maguire (1991) "The mgtB Mg<+ Transport Locus of Salmo­nella typhimurium Encodes a P-type ATPase", J. Biol. Chem. 266:815-823.

Snavely, M.D., S.A. Gravina, T.T. Cheung, C.G. Miller, and M.E. Maguire. (1991) "Magnesium Transport in Salmonella typhimurium: Regulation of mgtA and mgtB Expression", J. Biol. Chem. 266:824-829.

Portillo, F. G.-D., J.W. Foster, M.E. Maguire and B.B. Finlay (1992) "Characterization of the mi­croenvironment of Salmonella typhimurium-containing vacuoles within MDCK epithelial cells", Molecular Microbiology, 6:3289-3297

Smith, R.L. J.L. Banks, M.D. Snavely and M.E. Maguire (1993) "The corA Mg<+ Transport Se­quences of Salmonella typhimurium and Escherichia coli Identify a New Class of Transport System", J. Biol. Chem. 268: 14071-14080.

Smith, D.L., T. Tao and M.E. Maguire (1993) "Membrane Topology of a P-Type ATPase, the MgtB Mg2+ Transporter of Salmonella typhimurium," J. Biol. Chem. 268: 22469-22479.

Smith, R.L., L. Thompson and M.E. Maguire (1995) "Cloning and Characterization of mgtE, A New Class of Mg2+ Transporter from Bacillus firmus OF4," J. Bacteriology 177:1233-1238.

Townsend, D.T., A.J. Esenwine, J. George, III, D. Bross, M.E. Maguire, and R. L. Smith (1995) “Cloning of the mgtE Mg2+ Transporter from Providencia stuartii and the Distribution of mgtE in Gram-Negative and Gram-Positive Bacteria”, J. Bacteriology 177: 5350-5354.

Smith, R.L., E. Gottlieb, L.M. Kucharski and M.E. Maguire (1998) “Functional Similarity between Archaeal and Bacterial CorA Magnesium Transporters,” J. Bacteriology 180:2788-2791.