Participant supervision in co-therapy.

The present paper describes a model for supervision through co-therapy, developed in a training framework for interns of clinical psychology. The format presented includes a senior therapist and an intern as co-therapists. The model is conceptualized as one of participant supervision in psychodynamic psychotherapy. As such, the model is comprised of two elements. 1. Two therapists work together with one or more patient during a session. 2. The definition of the process as a supervisory situation, beyond the co-work in therapy of the two therapists. We offer the model as a significant and unique supplementary experience for both supervisor and supervise. The supervisory process is based on the principle of "reflection in action," and the actual participation of both partners in the clinical work, facilitating their mutual growth.

Small is mighty: EmrE, a multidrug transporter as an experimental paradigm.

EmrE is a multidrug transporter from Escherichia coli that functions as a homooligomer and is unique in its small size. In each monomer there are four tightly packed transmembrane segments and one membrane-embedded charged residue. This residue provides the basis for the coupling mechanism as part of a binding site "time shared" by substrates and protons.

Precious things come in little packages.

The 110-amino acid multidrug transporter from E. coli, EmrE, is a member of the family of MiniTexan or Smr drug transporters. EmrE can transport acriflavine, ethidium bromide, tetraphenylphosphonium (TPP+), benzalkonium and several other drugs with relatively high affinities. EmrE is an H+/drug antiporter, utilizing the proton electrochemical gradient generated across the bacterial cytoplasmic membrane by exchanging two protons with one substrate molecule. The EmrE multidrug transporter is unique in its small size and hydrophobic nature. Hydropathic analysis of the EmrE sequence predicts four alpha-helical transmembrane segments. This model is experimentally supported by FTIR studies that confirm the high alpha-helicity of the protein and by high-resolution heteronuclear NMR analysis of the protein structure. The TMS of EmrE are tightly packed in the membrane without any continuous aqueous domain, as was shown by Cysteine scanning experiments. These results suggest the existence of a hydrophobic pathway through which the substrates are translocated. EmrE is functional as a homo-oligomer as suggested by several lines of evidence, including co-reconstitution experiments of wild-type protein with inactive mutants in which negative dominance has been observed. EmrE has only one membrane embedded charged residue, Glu-14, that is conserved in more than fifty homologous proteins and it is a simple model system to study the role of carboxylic residues in ion-coupled transporters. We have used mutagenesis and chemical modification to show that Glu-14 is part of the substrate-binding site. Its role in proton binding and translocation was shown by a study of the effect of pH on ligand binding, uptake, efflux and exchange reactions. We conclude that Glu-14 is an essential part of a binding site, common to substrates and protons. The occupancy of this site is mutually exclusive and provides the basis of the simplest coupling of two fluxes. Because of some of its properties and its size, EmrE provides a unique system to understand mechanisms of substrate recognition and translocation.

Psychoanalysts' multiple relational perspectives.

The specific contribution of the person of the analyst--his or her attitudes, fantasies, and entire range of emotional responses to the patient--have become the subject of much investigation in psychoanalytic literature. This paper describes the phenomenon of distinct and sometimes contradictory self-experiences in analysts that develop as part of the moment-to-moment process of a predominantly adaptive coping mechanism. It is suggested that at any given point, the analyst's perspectives (reflecting various self-states), like those of the patient, are multiple, and that the analyst "choose" to place one such perspective at the center of experience. By choosing a certain self-state, the analyst can adopt, for example, a warm and loving stance with a regressed and demanding patient, or become harsh (e.g., setting boundaries, ending a session) with one who seeks affection and protection. This paper also suggests that the capacity to move between versions of self-states, to see them as complementary even when they are paradoxical, promotes a deeper understanding of paradoxes in the personality of the patient. Only when the analyst maintains a dialogue between various dissociated aspects of his or her analytic experience can a dialogue of this kind begin in the patient.

A single carboxyl mutant of the multidrug transporter EmrE is fully functional.

EmrE, a multidrug transporter from Escherichia coli removes toxic compounds from the cell in exchange with protons. Glu-14 is the only charged residue in the putative membrane domains and is fully conserved in more than 50 homologues of the protein. This residue was shown to be an essential part of the binding site, common to protons and substrate. EmrE bearing a single carboxylic residue, Glu-14, shows uptake and binding properties similar to those of the wild type. This suggests that a small protein bearing only 110 amino acids with a single carboxyl in position 14 is the most basic structure that shows ion-coupled transport activity. The role of Glu-14 in substrate binding was examined by using dicyclohexylcarbodiimide, a hydrophobic carbodiimide that is known to react with carboxyls. Tetraphenylphosphonium binding to both wild type and the single carboxyl mutant is inhibited by dicyclohexylcarbodiimide in a dose-dependent manner. Ethidium and other substrates of EmrE prevent this inhibition with an order of potency in accord with their apparent affinities. This suggests that dicyclohexylcarbodiimide binding is sterically prevented by the substrate, supporting the contention that Glu-14, the reactive residue, is part of the substrate-binding site.

A model for coupling of H(+) and substrate fluxes based on "time-sharing" of a common binding site.

Both prokaryotic and eukaryotic cells contain an array of membrane transport systems maintaining the cellular homeostasis. Some of them (primary pumps) derive energy from redox reactions, ATP hydrolysis, or light absorption, whereas others (ion-coupled transporters) utilize ion electrochemical gradients for active transport. Remarkable progress has been made in understanding the molecular mechanism of coupling in some of these systems. In many cases carboxylic residues are essential for either binding or coupling. Here we suggest a model for the molecular mechanism of coupling in EmrE, an Escherichia coli 12-kDa multidrug transporter. EmrE confers resistance to a variety of toxic cations by removing them from the cell interior in exchange for two protons. EmrE has only one membrane-embedded charged residue, Glu-14, which is conserved in more than 50 homologous proteins. We have used mutagenesis and chemical modification to show that Glu-14 is part of the substrate-binding site. Its role in proton binding and translocation was shown by a study of the effect of pH on ligand binding, uptake, efflux, and exchange reactions. The studies suggest that Glu-14 is an essential part of a binding site, which is common to substrates and protons. The occupancy of this site by H(+) and substrate is mutually exclusive and provides the basis of the simplest coupling for two fluxes.

A common binding site for substrates and protons in EmrE, an ion-coupled multidrug transporter.

EmrE is an Escherichia coli 12-kDa multidrug transporter, which confers resistance to a variety of toxic cations by removing them from the cell interior in exchange with two protons. EmrE has only one membrane-embedded charged residue, Glu-14, that is conserved in more than 50 homologous proteins and it is a simple model system to study the role of carboxylic residues in ion-coupled transporters. We have used mutagenesis and chemical modification to show that Glu-14 is part of the substrate binding site. Its role in proton binding and translocation was shown by a study of the effect of pH on ligand binding, uptake, efflux and exchange reactions. We conclude that Glu-14 is an essential part of a binding site, common to substrates and protons. The occupancy of this site is mutually exclusive and provides the basis of the simplest coupling of two fluxes.

An essential glutamyl residue in EmrE, a multidrug antiporter from Escherichia coli.

EmrE is an Escherichia coli 12-kDa protein that confers resistance to toxic compounds, by actively removing them in exchange with protons. The protein includes eight charged residues. Seven of these residues are located in the hydrophilic loops and can be replaced with either Cys or another amino acid bearing the same charge, without impairing transport activity. Glu-14 is the only charged residue in the membrane domain and is conserved in all the proteins of the family. We show here that this residue is the site of action of dicyclohexylcarbodiimide, a carbodiimide known to act in hydrophobic environments. When Glu-14 was replaced with either Cys or Asp, resistance was abolished. Whereas the E14C mutant displays no transport activity, the E14D protein shows efflux and exchange at rates about 30-50% that of the wild type. The maximal DeltapH-driven uptake rate of E14D is only 10% that of the wild type. The mutant shows a different pH profile in all the transport modes. Our results support the notion that Glu-14 is an essential part of a binding domain shared by substrates and protons but mutually exclusive in time. This notion provides the molecular basis for the obligatory exchange catalyzed by EmrE.

NMR investigation of the multidrug transporter EmrE, an integral membrane protein.

EmrE is an Escherichia coli multidrug transport protein that confers resistance to a wide range of toxicants by active transport across the bacterial cell membrane. The highly hydrophobic polytopic integral membrane protein has been purified and studied in its full-length form by high-resolution NMR spectroscopy in a mixture of chloroform/methanol/water (6:6:1, by vol.). Full activity is maintained after reconstitution of the protein into proteoliposomes from this solvent mixture. A series of heteronuclear (1H-15N) two- and three-dimensional experiments, as well as triple resonance experiments, were applied to the 110-residue protein and led to the assignment of the 1H, 15N and a large part of the 13C backbone resonances as well as many of the sidechain resonances. A preliminary analysis of the secondary structure, based on sequential NOE connectivities, deviation of chemical shifts from random coil values and 3J(NH-H alpha) coupling constants supports a model where the protein forms four alpha-helices between residues 4-26 (TM1), 32-53 (TM2), 58-76 (TM3) and 85-106 (TM4). For the residues of helices TM2 and TM3 a significant line broadening occurs due to slow conformational processes.

Parental care and intrusiveness as predictors of the abilities-achievement gap in adolescence.

In this study we examined relations between adolescents' perception of parental care and intrusiveness and the abilities-achievement gap. Cognitive abilities and academic achievement were assessed for 200 Israeli 10th graders. Representations of maternal and paternal care and intrusiveness and externalizing and internalizing symptoms were self-reported. Gender differences were found for the abilities-achievement gap. Boys' achievement in mathematics and language was significantly lower than could be expected from abilities in these domains. Representations of maternal care predicted achievement while aptitude and socioemotional symptoms were controlled and moderated the relations of abilities and achievement. Paternal representations were unrelated to abilities or achievement. Among boys, maternal intrusiveness had a unique contribution to the prediction of achievement, above and beyond abilities, socioemotional symptoms, and maternal care. The relevance of the findings to cognitive and attachment perspectives on adolescent achievement is discussed.

EmrE, the smallest ion-coupled transporter, provides a unique paradigm for structure-function studies.

EmrE is an Escherichia coli multidrug transporter which confers resistance to a wide variety of toxicants by actively removing them in exchange for hydrogen ions. EmrE is a highly hydrophobic 12 kDa protein which has been purified by taking advantage of its unique solubility in organic solvents. After solubilization and purification, the protein retains its ability to transport as judged from the fact that it can be reconstituted in a functional form. Hydrophobicity analysis of the sequence yielded four putative transmembrane domains of similar sizes. Results from transmission Fourier transform infrared measurements agree remarkably well with this hypothesis and yielded alpha-helical estimates of 78% and 80% for EmrE in CHCl3:MeOH and 1,2-dimyristoyl phosphocholine, respectively. Furthermore, the fact that most of the amide groups in the protein do not undergo amide-proton H/D exchange implies that most (approximately 80%) of the residues are embedded in the bilayer. These observations are only consistent with four transmembrane helices. A domain lined by Cys41 and Cys95 accessible only to substrates such as the organic mercurial 4-(chloromercuri)benzoic acid has been identified. Both residues are asymmetric in their location with respect to the plane of the membrane, Cys95 being closer than Cys41 to the outside face of the membrane. In co-reconstitution experiments of wild-type protein with three different inactive mutants, negative dominance has been observed. This phenomenon suggests that EmrE is functional as a homo-oligomer.

Negative dominance studies demonstrate the oligomeric structure of EmrE, a multidrug antiporter from Escherichia coli.

EmrE, the smallest known ion-coupled transporter, is an Escherichia coli 12-kDa protein 80% helical and soluble in organic solvents. EmrE is a polyspecific antiporter that exchanges hydrogen ions with aromatic toxic cations such as methyl viologen. Since it is many times smaller than the classical consensus 12 transmembrane segments transporters, it was particularly interesting to determine its oligomeric state. For this purpose, a series of nonfunctional mutants has been generated and characterized to test their effect on the activity of the wild-type protein upon mixing. As opposed to the wild type, these mutants do not confer resistance to methyl viologen, ethidium bromide, or a series of other toxicants. Co-expression of each of the nonfunctional mutants with the wild-type protein results in a reduction in the ability of the functional transporter to confer resistance to several toxicants. To perform mixing experiments in vitro, all the mutants have been purified by extraction with organic solvents, reconstituted in proteoliposomes, and found to be inactive. When co-reconstituted with wild-type protein, they inhibit the activity of the latter in a dose-dependent form up to full inhibition. We assume that this inhibition is due to the formation of mixed oligomers in which the presence of one nonfunctional subunit causes full inactivation. A binomial analysis of the results based on the latter assumptions do not provide statistically significant answers but suggests that the oligomer is composed of three subunits. The results described provide the first in vitro demonstration of the functional oligomeric structure of an ion-coupled transporter.

EmrE, an Escherichia coli 12-kDa multidrug transporter, exchanges toxic cations and H+ and is soluble in organic solvents.

The smallest membrane protein shown to catalyze ion-coupled transport is documented in this report. A gene coding for a small 110-amino acid membrane protein (emrE or mvrC) has been previously identified and cloned and shown to render Escherichia coli cells resistant to methyl viologen and to ethidium. In this report, it is shown that the resistance is due to extrusion of the toxic compounds in a process that requires a proton electrochemical gradient rather than ATP. For this purpose, cells in which the unc gene was inactivated were used so that the interconversion between the proton gradient and ATP is not possible, and the effect of agents, which specifically affect either of them, was tested on transport of ethidium in the intact cell. In addition, EmrE has been overexpressed and metabolically labeled with [35S]methionine. Strikingly, the protein can be quantitatively extracted with a mixture of organic solvents such as chloroform:methanol and is practically pure after this extraction. Moreover, after addition of E. coli lipids to the chloroform:methanol extract, EmrE has been reconstituted in proteoliposomes loaded with ammonium chloride. Upon dilution of the proteoliposomes in ammonium-free medium, a pH gradient was formed that drove transport of ethidium and methyl viologen into the proteoliposome. Both substrates compete with each other and exchange with previously transported solute. EmrE is a multidrug transporter of a novel type, and, because of its size and its solubility properties, it provides a unique model to study structure-function aspects of transport reactions in ion-coupled processes.

Integrating a shared patient-psychotherapist crisis into one's professional identity: Israeli psychotherapists look back at the Gulf War.

One year after the Gulf war, psychotherapists' recollections of their professional functioning and personal reactions during the war were investigated in an attempt to understand better how these events had been integrated into their professional identity. The war had been an extremely stressful time that had brought a real threat of mass destruction. Memories were investigated along three independent variables: time, proximity to directly affected areas, and professional experience. Results indicate that psychotherapists remember themselves as having been more available to their work and having been less affected than what they reported during the war. The difficulty for psychotherapists in integrating their limitations into their professional identity is discussed.