Sequence-specific assignment of the PAH2 domain of Sin3B free and bound to Mad1.
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Amino Acid Sequence↗
Biomedical subjects
A M Kaan
Publications and source records attributed to A M Kaan.
The Mad1-Sin3B interaction involves a novel helical fold.
Sin3A or Sin3B are components of a corepressor complex that mediates repression by transcription factors such as the helix-loop-helix proteins Mad and Mxi. Members of the Mad/Mxi family of repressors play important roles in the transition between proliferation and differentiation by down-regulating the expression of genes that are activated by the proto-oncogene product Myc. Here, we report the solution structure of the second paired amphipathic helix (PAH) domain (PAH2) of Sin3B in complex with a peptide comprising the N-terminal region of Mad1. This complex exhibits a novel interaction fold for which we propose the name 'wedged helical bundle'. Four alpha-helices of PAH2 form a hydrophobic cleft that accommodates an amphipathic Mad1 alpha-helix. Our data further show that, upon binding Mad1, secondary structure elements of PAH2 are stabilized. The PAH2-Mad1 structure provides the basis for determining the principles of protein interaction and selectivity involving PAH domains.
Amino Acid Sequence↗
Isolation and functional characterization of two distinct sexual-stage-specific promoters of the human malaria parasite Plasmodium falciparum.
Transmission of malaria depends on the successful development of the sexual stages of the parasite within the midgut of the mosquito vector. The differentiation process leading to the production of the sexual stages is delineated by several developmental switches. Arresting the progression through this sexual differentiation pathway would effectively block the spread of the disease. The successful development of such transmission-blocking agents is hampered by the lack of a detailed understanding of the program of gene expression that governs sexual differentiation of the parasite. Here we describe the isolation and functional characterization of the Plasmodium falciparum pfs16 and pfs25 promoters, whose activation marks the developmental switches executed during the sexual differentiation process. We have studied the differential activation of the pfs16 and pfs25 promoters during intraerythrocytic development by transfection of P. falciparum and during gametogenesis and early sporogonic development by transfection of the related malarial parasite P. gallinaceum. Our data indicate that the promoter of the pfs16 gene is activated at the onset of gametocytogenesis, while the activity of the pfs25 promoter is induced following the transition to the mosquito vector. Both promoters have unusual DNA compositions and are extremely A/T rich. We have identified the regions in the pfs16 and pfs25 promoters that are essential for high transcriptional activity. Furthermore, we have identified a DNA-binding protein, termed PAF-1, which activates pfs25 transcription in the mosquito midgut. The data presented here shed the first light on the details of processes of gene regulation in the important human pathogen P. falciparum.
Animals↗
Immunological properties of recombinant proteins of the transmission blocking vaccine candidate, Pfs48/45, of the human malaria parasite Plasmodium falciparum produced in Escherichia coli.
A precondition for the development of a transmission blocking vaccine based on the sexual stage-specific surface antigen Pfs48/45 of Plasmodium falciparum is its heterologous synthesis in a native state. Here we describe the production of recombinant Pfs48/45 in Escherichia coli. Two recombinant proteins, of which one is a glutathione-S-transferase fusion protein, were produced. Enzyme-linked immunosorbent assays showed that at least a subfraction of the recombinant proteins had a conformation capable of binding transmission blocking monoclonal antibodies. However, despite the fact that both proteins were very immunogenic, they did not induce transmission blocking immunity in mice or rabbits. Immunological studies with congenic mouse strains demonstrated that immune responses could be boosted with gametocyte extracts and were not restricted to a particular class II major histocompatibility complex haplotype.
Animals↗
Adjunctive use of inhaled nitric oxide during implantation of a left ventricular assist device.
BACKGROUND: The aim of this study was to evaluate the efficacy of inhaled nitric oxide in the prevention and reversal of pulmonary hypertension during and after left ventricular assist device implantation. METHODS: Inhaled nitric oxide (20 ppm) was administered to seven consecutive patients undergoing implantation of a left ventricular assist device at the time of implantation and for the first 24 hours after operation. RESULTS: Withdrawal of inhaled nitric oxide at 24 hours after operation was associated with a significant rise in both the transpulmonary gradient (from 8+/-1 to 14+/-2 mm Hg, p < 0.01) and in pulmonary vascular resistance (from 110+/-19 to 196+/-32 dynes x sec x cm[-5], p < 0.01). In two patients, the rise in pulmonary vascular resistance resulted in a critical fall in left ventricular assist device flow and hemodynamic deterioration, necessitating urgent reinstitution of inhaled nitric oxide. CONCLUSION: The administration of inhaled nitric oxide at the time of left ventricular assist device implantation prevents rises in pulmonary vascular resistance that in some patients result in critical reductions in left ventricular assist device flow. We suggest that inhaled nitric oxide is a useful adjunctive treatment that should be routinely available at the time of left ventricular assist device implantation.
Administration, Inhalation↗
Plasmodium reichenowi: deduced amino acid sequence of sexual stage-specific surface antigen Prs48/45 and comparison with its homologue in Plasmodium falciparum.
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Amino Acid Sequence↗
Cloning and expression of the gene coding for the transmission blocking target antigen Pfs48/45 of Plasmodium falciparum.
The gene encoding the gametocyte/gamete-specific membrane protein Pfs48/45 of Plasmodium falciparum has been cloned. The Pfs48/45 gene is a non-interrupted, single copy gene that codes for a hydrophobic, non-repetitive protein of 448 amino acid residues containing a putative signal peptide at the N-terminus, a hydrophobic C-terminus and 7 potential N-glycosylation sites. Antibodies directed against a Pfs48/45-glutathione-S-transferase fusion protein reacted with both the 45-kDa and 48-kDa proteins of gametocytes. When Pfs48/45 is expressed in the baculovirus-insect cell system the recombinant Pfs48/45 protein is targeted and exposed to the insect cell surface in such a configuration that it is recognized by transmission-blocking anti-45/48-kDa monoclonal antibodies.
Amino Acid Sequence↗
Gene V protein-mediated translational regulation of the synthesis of gene II protein of the filamentous bacteriophage M13: a dispensable function of the filamentous-phage genome.
Introduction of a deletion in the genome of wild-type M13 bacteriophage that eliminates translational repression of M13 gene II by its cognate gene V protein had no effect on phage viability. Furthermore, it was noted that gene V protein of phage IKe, a distant relative of M13, does not function as a translational repressor of its cognate gene II protein. The data strongly indicate that the gene V protein-mediated control of gene II expression in bacteriophage M13 is an evolutionary relic of the ancestral filamentous-phage genome and thus dispensable for proper filamentous-phage replication.
Base Sequence↗
A double-blind placebo-controlled trial of low-dose ganciclovir to prevent cytomegalovirus disease after heart transplantation.
BACKGROUND: The aim of this double-blind, placebo-controlled study was to determine whether a prolonged course of low-dose ganciclovir prevented the development of clinical cytomegalovirus disease after heart transplantation. METHODS: Fifty-six consecutive patients were stratified into two groups: cytomegalovirus-positive recipients (n = 40) and cytomegalovirus-negative recipients of organs from cytomegalovirus-positive donors (n = 16). All patients received equine antithymocyte globulin induction for 7 days and maintenance doses of cyclosporine, azathioprine, and prednisolone. Ganciclovir (5 mg/kg intravenously) or matching placebo was given with the premedication, three times weekly for the first 6 weeks after transplantation and for another 2 weeks for each treated rejection episode between 6 and 12 weeks. RESULTS: Ganciclovir prophylaxis reduced the actuarial incidence of cytomegalovirus disease from 71% to 11% in cytomegalovirus-mismatched patients (p < 0.01). Ganciclovir prophylaxis did not reduce the incidence of cytomegalovirus disease in cytomegalovirus-positive recipients (25% in both placebo and ganciclovir groups) but did delay its onset and reduce its morbidity. There were no adverse reactions during ganciclovir administration. Gastritis was the most common clinical manifestation of cytomegalovirus disease. Pneumonitis and myocarditis were seen only in placebo-treated cytomegalovirus-mismatched patients. All patients with clinical cytomegalovirus disease responded to ganciclovir, 10 mg/kg/day for 2 weeks. CONCLUSIONS: Prolonged low-dose ganciclovir prophylaxis after heart transplantation reduces the incidence of cytomegalovirus disease in cytomegalovirus-mismatched patients and reduces the morbidity of cytomegalovirus disease in cytomegalovirus-positive recipients.
Actuarial Analysis↗