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Yu X, Barnhill RL, Graves DT. Expression of monocyte chemoattractant protein-1 in delayed type hypersensitivity reactions in the skin. J Transl Med 1994; 71:226-35. [PMID: 8078302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Monocyte chemoattractant Protein-1 (MCP-1) is a potent chemotactic factor for monocytes. Because many inflammatory dermatoses are characterized by mononuclear cell infiltrates, it is reasonable to postulate that MCP-1 might be involved in their pathogenesis. To date, no in vivo studies have been published concerning the expression of MCP-1 in this context. The aim of this study was to elucidate the expression of MCP-1 in human inflammatory skin diseases which are thought to involve delayed type hypersensitivity reactions. EXPERIMENTAL DESIGN Expression of MCP-1 was examined in normal skin and three classes of inflammatory skin reactions by immunohistochemistry experiments utilizing a monospecific MCP-1 antiserum. The distribution of monocytes/macrophages and T lymphocytes was determined by immunohistochemistry using antibodies to specific cell surface markers. RESULTS Immunostaining with MCP-1 antiserum demonstrated strong MCP-1 expression in lichenoid dermatitis, dermal hypersensitivity reactions, and spongiotic dermatitis. In contrast, normal skin showed minimal MCP-1 expression in the dermis. The cell types displaying MCP-1 expression were endothelial cells of dermal microvessels that were surrounded by lymphocytic infiltrates and monocytes/macrophages at the periphery of the perivascular infiltrates. Occasionally, MCP-1-positive mononuclear cells were present both in the infiltrates and in a diffuse pattern in the surrounding dermis. Keratinocytes were found to produce MCP-1 constitutively in normal skin and in inflamed conditions. The pattern of MCP-1 expression was similar to the pattern observed for monocyte/macrophage distribution, whereas the pattern of MCP-1 expression was different from the pattern of T lymphocyte distribution. CONCLUSIONS We observed an enhanced expression of MCP-1 in inflammatory skin conditions. The expression of MCP-1 provides a mechanistic explanation for the increased recruitment of monocytes/macrophages in cell-mediated immune response such as delayed type hypersensitivity reactions in the skin.
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1052
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Yu X, Bi W, Weiss SR, Leibowitz JL. Mouse hepatitis virus gene 5b protein is a new virion envelope protein. Virology 1994; 202:1018-23. [PMID: 8030202 DOI: 10.1006/viro.1994.1430] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Highly purified radiolabeled mouse hepatitis virus (MHV) A59 contained a previously overlooked protein which coelectrophoreses with the gene 5b product immunoprecipitated from infected cells. The gene 5b protein is post-translationally acylated. Rabbit antibody raised against a recombinant gene 5b protein expressed in Escherichia coli neutralized viral infectivity in the presence of complement, although not in the absence of complement. Immunofluorescent staining of MHV-infected cells with two anti-peptide antibodies revealed that the gene 5b product is membrane-associated and is transported to the cell surface, findings consistent with the prediction of a membrane-spanning segment in the gene 5b polypeptide. These results suggest strongly that the gene 5b polypeptide represents a new MHV virion envelope protein which is homologous to the TGEV ORF 4 and IBV 3c proteins.
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1053
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Ren Z, Ding W, Su Z, Gu X, Huang H, Liu J, Yan Q, Zhang W, Yu X. Mechanisms of brain injury with deep hypothermic circulatory arrest and protective effects of coenzyme Q10. J Thorac Cardiovasc Surg 1994; 108:126-33. [PMID: 8028355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Sixteen dogs, divided randomly into a control group and coenzyme Q10 group (10mg/kg, intraperitoneally before the operation), underwent deep hypothermic circulatory arrest with cardiopulmonary bypass, as is done clinically. At four time points cerebral cortex and cerebrospinal fluid specimens were collected to study free radical formation, energy metabolism, and ultrastructure. During cardiopulmonary bypass cerebral electron spin resonance spectra and malondialdehyde contents were progressively higher than before bypass, especially at the 60 minutes of circulatory arrest and 30 minutes of reperfusion (p1 < 0.01, p2 < 0.05). In the coenzyme Q10 group at the latter two time points, they had increased less than in the control group at same time points (p1 < 0.02, p2 < 0.005). Adenosine triphosphate content in the cortex during bypass decreased gradually from the prebypass level (p1 < 0.02, p2 = p3 < 0.001), while lactate in cerebrospinal fluid increased (p1 < 0.05, p2 = p3 < 0.001). In the coenzyme Q10 group, adenosine triphosphate at the latter two time points was greater than that in the control group (p1 = p2 < 0.05), while the lactate changes were not significantly different from control at each time point (all p > 0.05). Ultrastructure of the cortex was normal before bypass and almost normal during bypass, but it was obviously abnormal at 60 minutes of circulatory arrest and more seriously abnormal at 30 minutes of reperfusion. In the coenzyme Q10 group the abnormality was obviously reduced. The results suggest that oxygen-derived free radicals and abnormal energy metabolism might play critical roles in brain ischemia/reperfusion injury. Coenzyme Q10 could protect the brain by improving cerebral metabolism.
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1054
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Mylin LM, Bushman VL, Long RM, Yu X, Lebo CM, Blank TE, Hopper JE. SIP1 is a catabolite repression-specific negative regulator of GAL gene expression. Genetics 1994; 137:689-700. [PMID: 8088514 PMCID: PMC1206028 DOI: 10.1093/genetics/137.3.689] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The yeast Snf1p kinase is required for normal expression of many genes involved in utilization of non-glucose carbon. Snf1p is known to associate with several proteins. One is Sip1p, a protein that becomes phosphorylated in the presence of Snf1p and thus is a candidate Snf1p kinase substrate. We have isolated the SIP1 gene as a multicopy suppressor of the gal83-associated defect in glucose repression of GAL gene expression. Multicopy SIP1 also suppressed the gal82-associated defect in glucose repression, suggesting that SIP1, GAL83 and GAL82 function interdependently. Multicopy SIP1 gene reduces GAL1, GAL2, GAL7 and GAL10 gene expression three- to fourfold in cells grown in the presence of glucose but has no effect in cells grown on nonrepressing carbon. Sip1-deletion cells exhibited a two- to threefold increase in GAL gene expression compared to wild-type cells when grown on glucose. These studies show that SIP1 is a catabolite repression-specific negative regulator of GAL gene expression. Northern analysis revealed two SIP1 transcripts whose relative abundance changed with carbon source. Western blots revealed that Sip1p abundance is not markedly affected by carbon source, suggesting that Sip1p may be regulated post-translationally.
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1055
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Yu X, Hao L, Inesi G. A pK change of acidic residues contributes to cation countertransport in the Ca-ATPase of sarcoplasmic reticulum. Role of H+ in Ca(2+)-ATPase countertransport. J Biol Chem 1994; 269:16656-61. [PMID: 8206985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Proteoliposomal vesicles reconstituted with sarcoplasmic reticulum ATPase and exogenous lipids sustain ATP-dependent Ca2+ uptake and H+ ejection, as well as net charge displacement by Ca2+. We have studied the effect of lumenal (inner) and medium (extravesicular) pH variations on the countertransport ratios of H+ and Ca2+. We find that the Ca2+/H+ molar ratio is approximately 1 when the lumenal and medium pH is near neutrality, but changes with a specific pattern when the medium pH is varied in the presence of a constant lumenal pH and when the lumenal pH is varied in the presence of a constant medium pH. Empirical analysis of the experimental data shows that the apparent pK of the residue(s) releasing H+ into the medium is approximately 6.1, whereas the apparent pK of the residue(s) binding lumenal H+ is approximately 7.7. Assuming that the same acidic residues are involved in H+ and Ca2+ countertransport, our findings suggest a lower affinity for H+ in their outward orientation (prevalent in the ground state of the enzyme) and a higher affinity for H+ in lumenal orientation (prevalent in the phosphorylated state of the enzyme). Cyclic pK changes, coupled to ATP utilization, promote cation exchange, Ca2+ uptake, and H+ ejection by the vesicles. The stoichiometry of countertransport and net charge displacement is matched by a corresponding electrogenic behavior. A calculation of voltage development related to initial rates of charge transfer (dV/dt = (dQ/dt)/Cm) is given as a corrective replacement of a previous steady state calculation.
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1056
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Yu QC, Matsuda Z, Yu X, Ito S, Essex M, Lee TH. An electron-lucent region within the virion distinguishes HIV-1 from HIV-2 and simian immunodeficiency virus. AIDS Res Hum Retroviruses 1994; 10:757-61. [PMID: 8074937 DOI: 10.1089/aid.1994.10.757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Ultrastructural comparisons of immature or budding particles of human immunodeficiency virus (HIV) types 1 and 2 and simian immunodeficiency virus of macaques (SIVmac) revealed no significant difference between these genetically distinct, but related, viruses. However, a region encompassing the core of mature HIV-1 virions was found to be more electron lucent than that observed in HIV-2 and SIVmac. This ultrastructural distinction cannot be attributed to HIV-1-specific vpu, HIV-2/SIV-specific vpx, or virion-associated vpr gene products.
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1057
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Yu X, Hao L, Inesi G. A pK change of acidic residues contributes to cation countertransport in the Ca-ATPase of sarcoplasmic reticulum. Role of H+ in Ca(2+)-ATPase countertransport. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)89440-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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1058
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Schwartz RD, Huff RA, Yu X, Carter ML, Bishop M. Postischemic diazepam is neuroprotective in the gerbil hippocampus. Brain Res 1994; 647:153-60. [PMID: 8069699 DOI: 10.1016/0006-8993(94)91411-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In this study, we address the hypothesis that enhancement of gamma-aminobutyric acid (GABA) neurotransmission following an ischemic episode is neuroprotective in the hippocampus. Mongolian gerbils were subjected to transient forebrain ischemia for 5 min by occlusion of the carotid arteries and then administered diazepam (10 mg/kg i.p.) 30 min or 30 and 90 min following ischemia. Diazepam produced a significant decrease in both rectal and brain temperature (4-6 degrees C) in the sham and ischemic gerbils. 1 day following the onset of reperfusion, diazepam substantially reduced the hyperactivity normally induced by the ischemic episode. 7 days later, neuronal viability in the hippocampus was assessed. The single dose of diazepam completely protected the CA1 pyramidal cells of the hippocampus in 62% of the gerbils and the double dose of diazepam completely protected CA1 pyramidal neurons in 67% of the gerbils. There was a significant correlation between the degree of pyramidal cell degeneration in the CA1 area of the hippocampus measured 7 days following ischemia and the degree of hyperactivity measured 1 day following ischemia. Diazepam also prevented the loss of [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to GABA-gated chloride channels in the dendritic fields of the CA1 area of the hippocampus. Our findings support the hypothesis that enhancement of GABA neurotransmission following an ischemic event may offset neuronal excitability and prevent neuronal death in specific brain regions. We conclude that GABA-enhancing drugs, such as diazepam, are attractive candidates as neuroprotective agents following ischemic insults.
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1059
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Yu X, Raoult D. Monoclonal antibodies to Afipia felis--a putative agent of cat scratch disease. Am J Clin Pathol 1994; 101:603-6. [PMID: 8178767 DOI: 10.1093/ajcp/101.5.603] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Twelve hybridoma clones producing monoclonal antibodies to Afipia felis, a putative causative agent of cat scratch disease, were derived from BALB/c mice immunized with A felis. All 12 monoclonal antibodies were species-specific for A felis and reacted with lipopolysaccharide antigens of A felis. These monoclonal antibodies belong to immunoglobulin (Ig) G1, IgG2a, IgG2b, IgG3, and IgM isotypes. All monoclonal antibodies reacted with both agar-grown A felis and tissue culture-propagated A felis. Formalin fixation did not alter the reactivity of the antigen with the monoclonal antibodies. These monoclonal antibodies could be a useful tool for investigation of the disputed role of A felis in cat scratch disease.
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1060
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Yu X, Zipp GL, Davidson GW. The effect of temperature and pH on the solubility of quinolone compounds: estimation of heat of fusion. Pharm Res 1994; 11:522-7. [PMID: 8058609 DOI: 10.1023/a:1018910431216] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Although many reports involving fluoroquinolone agents have been published in the past decades, only a few address preformulation studies. In this paper, we describe the effect of temperature and pH on the aqueous solubility of two typically used quinolones, ciprofloxacin and norfloxacin. We measured the aqueous solubilities over the pH range of 5.5 to 9.5 at temperature of 6, 25, 30, and 40 degrees C. The intrinsic solubilities and the thermodynamic dissociation constants were determined from solubility data and the temperature dependence of the intrinsic solubility was evaluated using van't Hoff and Hildebrand plots. The heat of fusion was determined from these two plots. When the heat of fusion was compared to that measured from differential scanning calorimetry (DSC) studies, we found that the Hildebrand method overestimated, and the van't Hoff equation underestimated, the heat of fusion. From the absolute values of the relative errors, the Hildebrand plot produced the better results. DSC results show that the heat of fusion is 15.41 kcal/mol for ciprofloxacin and 7.88 kcal/mol for norfloxacin.
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1061
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Yu X, Raoult D. Serotyping Coxiella burnetii isolates from acute and chronic Q fever patients by using monoclonal antibodies. FEMS Microbiol Lett 1994; 117:15-9. [PMID: 8181707 DOI: 10.1111/j.1574-6968.1994.tb06735.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Four mouse monoclonal antibodies reacting with Coxiella burnetti lipopolysaccharide antigens were produced and used in serotyping 17 C. burnetii isolates from acute Q fever and Q fever endocarditis patients in France. Two monoclonal antibodies (1B2 and 3B6) were considered specific for the Priscilla strain, a representative of Q fever endocarditis isolates, and did not react with the Nine Mile strain, which is representative of acute Q fever isolates. Monoclonal antibodies Nos. 1B2 and 3B6 reacted with 75% (3/4) acute Q fever isolates and 85% (11/13) of endocarditis isolates from France. It is reasonable to conclude that Priscilla-like strains cause both acute Q fever and Q fever endocarditis. The hypothesis that Priscilla-like strains only are associated with Q fever endocarditis should be reconsidered.
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1062
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Yang H, Yu X, Zhang Y. [Free thyroxine in burn patient and its clinical significance]. ZHONGHUA ZHENG XING SHAO SHANG WAI KE ZA ZHI = ZHONGHUA ZHENG XING SHAO SHANG WAIKF [I.E. WAIKE] ZAZHI = CHINESE JOURNAL OF PLASTIC SURGERY AND BURNS 1994; 10:121-3. [PMID: 7922811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Using radioimmunoassay serum FT3 and FT4 and S-TSH were determined in 42 patients with different sizes of burn. The results were all in the normal range, indicating that there was only sufficient amount of thyroxine in trauma patients to maintain the lowest basal metabolism for living. The changes in the total T3 and T4 did not conform to that reported elsewhere. It deserves further clinical observation and study.
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Eremeeva M, Yu X, Raoult D. Differentiation among spotted fever group rickettsiae species by analysis of restriction fragment length polymorphism of PCR-amplified DNA. J Clin Microbiol 1994; 32:803-10. [PMID: 7910831 PMCID: PMC263128 DOI: 10.1128/jcm.32.3.803-810.1994] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Restriction fragment length polymorphism (RFLP) analysis of PCR-amplified genes was used to study spotted fever group (SFG) rickettsiae, extending the previous work of Regnery et al. (R.L. Regnery, C.L. Spruill, and B.D. Plikaytis, J. Bacteriol. 173:1576-1589, 1991). Twenty-six strains of SFG rickettsia were studied, including several recognized species which have never been studied (R. parkeri, R. helvetica, and R. japonica) as well as strains which are not currently classified. Two previously used primer pairs derived from the R. prowazekii citrate syntase gene and the R. rickettsii 190-kDa protein antigen gene were studied, as were primer pairs obtained from the R. rickettsii 120-kDa protein antigen gene. By using three amplifications and three enzyme digestions, it was possible to differentiate between almost all of the known SFG rickettsia species and to differentiate between several strains of the R. conorii complex. Two human pathogens, "R. africae" and the Israeli tick typhus rickettsia, were first separated by using BG-12 pair primer amplification and then RsaI restriction endonuclease digestion. The proposed simplified model of identification may be useful in studying the geographical distributions of SFG rickettsiae.
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1064
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Schwartz RD, Wagner JP, Yu X, Martin D. Bidirectional modulation of GABA-gated chloride channels by divalent cations: inhibition by Ca2+ and enhancement by Mg2+. J Neurochem 1994; 62:916-22. [PMID: 8113813 DOI: 10.1046/j.1471-4159.1994.62030916.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of the divalent cations Ca2+, Sr2+, Ba2+, Mg2+, Mn2+, and Cd2+ were studied on gamma-aminobutyric acidA (GABAA) responses in rat cerebral cortical synaptoneurosomes. The divalent cations produced bidirectional modulation of muscimol-induced 36Cl- uptake consistent with their ability to permeate and block Ca2+ channels. The order of potency for inhibition of muscimol responses was Ca2+ > Sr2+ > Ba2+, similar to the order for permeation of Ca2+ channels in neurons. The order of potency for enhancement of muscimol responses was Cd2+ > Mn2+ > Mg2+, similar to the order for blockade of Ca2+ channels in neurons. Neither Ca2+ nor Mg2+ caused accumulation of GABA in the extravesicular space due to increased GABA release or decreased reuptake of GABA by the synaptoneurosomes. The inhibition of muscimol responses by Ca2+ was most likely via an intracellular site of action because additional inhibition could be obtained in the presence of the Ca2+ ionophore, A23187. This confirms electrophysiologic findings in cultured neurons from several species. In contrast, the effects of Cd2+, Mn2+, and Mg2+ may be mediated via blockade of Ca2+ channels or by intracellular sites, although the results of these studies do not distinguish between the two loci. The effects of Zn2+ were also studied, because this divalent cation is reported to have widely divergent effects on GABAA responses. In contrast to other studies, we demonstrate that Zn2+ inhibits GABAA responses in an adult neuronal preparation. Zn2+ produced a concentration-dependent inhibition (limited to 40%) of muscimol responses with an EC50 of 60 microM. The inhibition of muscimol-induced 36Cl- uptake by Zn2+ was noncompetitive.(ABSTRACT TRUNCATED AT 250 WORDS)
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1065
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Orlova A, Yu X, Egelman EH. Three-dimensional reconstruction of a co-complex of F-actin with antibody Fab fragments to actin's NH2 terminus. Biophys J 1994; 66:276-85. [PMID: 8161679 PMCID: PMC1275692 DOI: 10.1016/s0006-3495(94)80791-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have decorated F-actin with Fab fragments of antibodies to actin residues 1-7. These antibody fragments do not strongly affect the rigor binding of myosin S-1 to actin, but do affect the binding of S-1 to actin in the presence of nucleotide (DasGupta, G., and E. Reisler, 1989. J. Mol. Biol. 207:833-836; 1991. Biochemistry. 30:9961-9966; 1992. Biochemistry. 31:1836-1841). Although the binding constant is rather low, we estimate that we have achieved about 85% occupancy of the actin sites. Three-dimensional reconstructions from electron micrographs of both negatively stained and frozen-hydrated filaments show that the Fab fragment is bound at the location of the NH2 terminus in the model of Holmes et al. (Holmes, K.C., D. Popp, W. Gebhard, and W. Kabsch. 1990. Nature. 347:37-44) for F-actin, excluding very different orientations of the actin subunit in the filament. Most of the mass of the antibody is not visualized, which is due to the large mobility of the NH2 terminus in F-actin, differences in binding angle within the polyclonal antibody population, or a combination of both of these possibilities.
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1066
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Yu X, Barnstable CJ. Characterization and regulation of the protein binding to a cis-acting element, RET 1, in the rat opsin promoter. J Mol Neurosci 1994; 5:259-71. [PMID: 7577368 DOI: 10.1007/bf02736726] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
RET 1 is a binding site for retinal nuclear proteins located at -136 to -110 bp in the rat opsin promoter, as defined by DNase protection assays. A similar sequence is found in the upstream flanking regions of many other photoreceptor genes in mammals and other species, including Drosophila. A 7-base consensus sequence, CAATTAG, is found in these genes and has the binding activity of the longer RET 1 element. A 40-kDa protein that binds to RET 1 has been purified over 2 x 10(5)-fold to apparent homogeneity by affinity chromatography. The RET 1 binding activity is first detectable at E18 and increases during the first two postnatal weels, At embryonic ages the retarded bands show an altered mobility and at early postnatal ages two bands are detected, with the adult band increasing and the embryonic band decreasing in intensity. Treatment of early postnatal retinas with bFGF increased the binding activity in nuclear extracts and caused a shift in migration of the retarded band to a position characteristic of the embryonic form of the complex. The results support the hypothesis that RET 1-like elements play an important role in rod photoreceptor development.
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Ahmad I, Yu X, Barnstable CJ. A cis-acting element, T alpha-1, in the upstream region of rod alpha-transducin gene that binds a developmentally regulated retina-specific nuclear factor. J Neurochem 1994; 62:396-9. [PMID: 8263543 DOI: 10.1046/j.1471-4159.1994.62010396.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The G protein transducin (T) is an integral component of the signal transduction pathway in photoreceptors. We have identified a cis-acting element, T alpha-1, in the upstream region of the mouse rod alpha-T (Tr alpha) gene that may be important for tissue-specific expression. T alpha-1 binds a retina-specific nuclear factor of apparent molecular mass of 90 kDa. Binding to the T alpha-1 site is developmentally regulated and peaks between postnatal days 6 and 9. This corresponds to the time of rod photoreceptor maturation and the rise in Tr alpha gene expression. The sequence of T alpha-1 shows homology with RET-1, a cis-acting element in the proximal promoter of opsin gene that binds a distinct retina-specific factor. T alpha-1 and RET-1 sequences may have been derived from a prototype T alpha-1/RET-1 sequence, evolved to confer photoreceptor specificity on retina-specific genes.
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Yu X, Brouqui P, Dumler JS, Raoult D. Detection of Ehrlichia chaffeensis in human tissue by using a species-specific monoclonal antibody. J Clin Microbiol 1993; 31:3284-8. [PMID: 7508458 PMCID: PMC266402 DOI: 10.1128/jcm.31.12.3284-3288.1993] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A mouse monoclonal antibody (MAb 1A9) was produced and used in detection of Ehrlichia chaffeensis in human tissues including kidney, liver, and lung by using an indirect immunohistologic stain. MAb 1A9 was specific to E. chaffeensis and did not react with other bacteria, including Ehrlichia canis, which is the organism most closely related to E. chaffeensis. It reacted with an epitope present in two surface proteins of E. chaffeensis with molecular masses of 29 and 27 kDa. E. chaffeensis was easily detected in human tissue by immunohistology with MAb 1A9. This study demonstrates that our MAb can provide a specific and simple method for detection of E. chaffeensis in clinical specimens for establishing an etiologic diagnosis of human ehrlichiosis; it may also provide a tool for the investigation of immunopathologic characteristics in infected patients.
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Cramer CL, Weissenborn D, Cottingham CK, Denbow CJ, Eisenback JD, Radin DN, Yu X. Regulation of Defense-related Gene Expression during Plant-Pathogen Interactions. J Nematol 1993; 25:507-518. [PMID: 19279804 PMCID: PMC2619434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Plants have evolved a broad array of defense mechanisms involved in disease resistance. These include synthesis of phytoalexin antibiotics and proteinase inhibitors, deposition of cell wall materials, and accumulation of hydrolytic enzymes such as chitinases. Resistance appears to depend on the ability of the host to recognize the pathogen rapidly and induce these defense responses in order to limit pathogen spread. Application of molecular technologies has yielded significant new information on mechanisms involved in pathogen recognition, signal transduction, and defense-related gene activation, and is leading to novel strategies for engineering enhanced disease resistance. We are using these approaches to analyze regulation of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR), a key enzyme mediating the production of terpenoid defense compounds. This enzyme is encoded by four genes in tomato; hmg2 gene expression is specifically associated with responses to pathogen or defense elicitors. Transgenic plants containing DNA constructs that fuse the hmg2 promoter to a reporter gene have been used to analyze both tissue specificity and patterns of defense-related expression. Because this gene is rapidly induced in tissues directly surrounding the site of ingress by a variety of pathogens, it may serve as a valuable tool in engineering new disease-resistance mechanisms.
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Sharom FJ, Yu X, Doige CA. Functional reconstitution of drug transport and ATPase activity in proteoliposomes containing partially purified P-glycoprotein. J Biol Chem 1993; 268:24197-202. [PMID: 7901214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
P-glycoprotein, the multidrug transporter, is proposed to act as an ATP-driven drug efflux pump. We previously reported the partial purification of P-glycoprotein from multidrug-resistant cells (Doige, C. A., Yu, X., and Sharom, F. J. (1992) Biochim. Biophys. Acta 1109, 149-160). We now report the reconstitution of this preparation into phospholipid bilayers using rapid detergent removal by gel filtration chromatography. The resulting proteoliposomes displayed ATP-dependent [3H]colchicine uptake over a time period of 0-4 min. No drug uptake was observed for liposomes of lipid alone, or liposomes reconstituted with a similar extract from drug-sensitive cells. Drug uptake was osmotically sensitive, and abolished by detergent permeabilization, indicating that it represented true transport into the vesicle lumen. Steady-state levels of drug uptake increased with drug concentration, approaching saturation at approximately 150 microM colchicine, with half-maximal accumulation at 50 microM. Drug was accumulated actively against a 5.6-fold concentration gradient. Multidrug resistance spectrum drugs and chemosensitizers inhibited colchicine uptake by P-glycoprotein proteoliposomes, whereas cytosine arabinoside and methotrexate had no effect. Reconstituted liposomes showed high levels of ATPase activity, which was stimulated over 2-fold by verapamil and trifluoperazine. These results suggest that P-glycoprotein functions as an active drug transporter with constitutive ATPase activity.
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1071
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Yu X, Antoniades HN, Graves DT. Expression of monocyte chemoattractant protein 1 in human inflamed gingival tissues. Infect Immun 1993; 61:4622-8. [PMID: 8406859 PMCID: PMC281213 DOI: 10.1128/iai.61.11.4622-4628.1993] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Gingival inflammation is initiated by bacterial colonization on the tooth surface. It is characterized by infiltration of mononuclear cells, a common feature of many forms of chronic inflammation. Monocyte chemoattractant protein 1 (MCP-1) is the predominant monocyte chemoattractant secreted by a variety of different cells in vitro. For this report, we examined MCP-1 expression in bacterially induced gingival inflammation by immunohistochemistry and in situ hybridization. The cell types expressing MCP-1 are identified as vascular endothelial cells and monocytes/macrophages. Correlation analysis shows that the number of cells expressing MCP-1 is related to the degree of inflammation. Our finding that MCP-1 is expressed in inflamed gingival tissue suggests that MCP-1 plays an important role in the recruitment of monocytes and amplification of inflammatory signals in bacterially induced inflammation.
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1072
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Yuan X, Yu X, Lee TH, Essex M. Mutations in the N-terminal region of human immunodeficiency virus type 1 matrix protein block intracellular transport of the Gag precursor. J Virol 1993; 67:6387-94. [PMID: 8411340 PMCID: PMC238073 DOI: 10.1128/jvi.67.11.6387-6394.1993] [Citation(s) in RCA: 202] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The matrix domain of human immunodeficiency virus type 1 Gag polyprotein was studied for its role in virus assembly. Deletion and substitution mutations caused a dramatic reduction in virus production. Mutant Gag polyproteins were myristoylated and had a high affinity for membrane association. Immunofluorescence staining revealed a large accumulation of mutant Gag precursors in the cytoplasm, while wild-type Gag proteins were primarily associated with the cell surface membrane. These results suggest a defect in intracellular transport of the mutant Gag precursors. Thus, in addition to myristoylation, the N-terminal region of the matrix domain is involved in determining Gag protein transport to the plasma membrane. Wild-type Gag polyproteins interacted with and efficiently packaged mutant Gag into virions. This finding is consistent with the hypothesis that intermolecular interaction of Gag polyproteins might occur in the cytoplasm prior to being transported to the assembly site on the plasma membrane.
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1073
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Davis EL, Joynt RB, Yu X, Wieczkowski G. Dentin bonding system shelf life and bond strength. AMERICAN JOURNAL OF DENTISTRY 1993; 6:229-31. [PMID: 7880464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The purpose of this study was to assess the shelf life of dentin bonding systems by means of bond strength testing. The systems evaluated were Mirage-Bond, All-Bond and Tenure. Specimens were tested immediately, and 1, 2, 3, 4, 5 and 12 months after opening the kits. Flat dentin surfaces were created on 210 extracted human molars that had been stored in saline. Ten specimens were prepared for each dentin bonding system at each shelf time. Each material was prepared and placed following the manufacturer's instructions. Prisma MicroFine resin composite was then placed. Shear bond strength testing was conducted using a universal testing machine. A two-way ANOVA indicated a significant interaction between bonding system and storage time (F = 2.28, P = 0.01). Multiple comparison tests indicated statistically significant bond strength differences by storage time for All-Bond and Mirage-Bond. In addition, a comparison of bonding systems at each storage time revealed significant differences at three of the seven times. These results suggest that shelf life for two of the three dentin bonding systems may be significantly shorter than currently presumed.
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1074
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Czakó M, Wilson J, Yu X, Márton L. Sustained root culture for generation and vegetative propagation of transgenic Arabidopsis thaliana. PLANT CELL REPORTS 1993; 12:603-606. [PMID: 24201871 DOI: 10.1007/bf00232807] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/1993] [Revised: 07/19/1993] [Indexed: 06/02/2023]
Abstract
Excised roots of wild-type and nitrate-reductase deficient mutant Arabidopsis thaliana (L.) HEYNH. can be propagated as sustained root cultures in liquid medium. Culture initiation from a single seedling required a two-day indoleacetic acid treatment at 0.05 mg/l concentration. Indoleacetic acid facilitated subculture but was not essential for sustained growth. This procedure has allowed the clonal propagation of roots derived from individual wildtype and mutant seedlings for more than 21 months. The cultured roots retained their shoot regeneration ability; however, a controlled desiccation treatment was required to restore it to the level of freshly excised roots. The chromosome number remained diploid and no evidence for the accumulation of recessive mutations was observed. The cultured roots are competent for Agrobacterium-mediated transformation. The sustained root culture technology allowed the maintenance of transgenic tissues in which expression of a dominant, seed-lethal gene (seed-specific pea vicilin promoter fused to diphtheria toxin A chain gene) precluded generative propagation.
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1075
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Yu X, Yu Q. Protective effect of Salmonella typhimurium Re-LPS antiserum. CHINESE MEDICAL SCIENCES JOURNAL = CHUNG-KUO I HSUEH K'O HSUEH TSA CHIH 1993; 8:151-6. [PMID: 8142630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
There is increasing evidence that antiserum to LPS can reduce the morbidity and mortality of Gram-negative bacterial infections. We report that antiserum to S. typhimurium SL 1102 (Re mutant strain) has excellent cross-protective activity. Antisera to these bacteria and to their Re-LPS were prepared in rabbits immunized with heat-killed bacterial cells and with Re-LPS preparations. Re-LPS antibody titers were tested by immune hemagglutination (IHA) and by ELISA. These antisera were found to be capable of protecting ICR mice against lethal challenge with S-type S. typhimurium 50014 (100 LD50), E. coli 0111:B4 (32 LD50), Pseudomonas aeruginosa (8 LD50) and Klebsiella pneumonia (16 LD50). We used gastric mucin (5%) as a virulence enhancing agent for the bacterial challenges. The IHA titer of antibody to the homologous strain proved to be much higher than that of other strains. Protection by the sera was 75-100%, 25% and 0% when injected 24, 48 or 72 h before the challenge, respectively. The survival rate was more than 50% when the antiserum was injected 5-7 h after challenge with a ten-fold or higher lethal dose. No protection was observed against such high challenge when the serum was injected later. According to these results, Re-LPS antiserum provides better protection than S-type specific antisera.
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1076
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Yu X, Inesi G. Effects of anions on the Ca2+, H+ and electrical gradients formed by the sarcoplasmic reticulum ATPase in reconstituted proteoliposomes. FEBS Lett 1993; 328:301-4. [PMID: 8348980 DOI: 10.1016/0014-5793(93)80948-t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The chaotropic character of several ions determines their partition on membrane interfaces with aqueous media as predicted by the Hofmeister series. However, specific characteristics of each individual ion determine its ability to cross the membrane and to influence Ca2+, H+ and electrical gradients produced by the sarcoplasmic reticulum (SR) Ca2+ pump in reconstituted proteoliposomal vesicles. Specific effects of this kind may be relevant to a variety of biological systems, including the excitation-contraction coupling of muscle fibers in which SR plays a prominent role.
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1077
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Yu X, Raisanen A, Haugstad G, Troullier N, Biasiol G, Franciosi A. Nonmagnetic-semimagnetic semiconductor heterostructures: Ge-Cd1-xMnxTe(110). PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:4545-4551. [PMID: 10008933 DOI: 10.1103/physrevb.48.4545] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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1078
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Friedmann AS, Memoli VA, Cheng SW, Yu X, North WG. Vasopressin and vasopressin-associated neurophysin are present in gastric and duodenal cells of Brattleboro and Long-Evans rats. Ann N Y Acad Sci 1993; 689:522-5. [PMID: 8373038 DOI: 10.1111/j.1749-6632.1993.tb55583.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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1079
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1080
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Yu X, Egelman EH. DNA conformation induced by the bacteriophage T4 UvsX protein appears identical to the conformation induced by the Escherichia coli RecA protein. J Mol Biol 1993; 232:1-4. [PMID: 8331653 DOI: 10.1006/jmbi.1993.1363] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The study of homologous genetic recombination has been dominated by the RecA protein of Escherichia coli, which is involved in DNA recombination and repair, as well as phage induction, in vivo. The active form of the RecA protein is a helical filament formed on DNA in the presence of ATP, and within this filament, the DNA is extensively stretched to about 5.1 A rise per base-pair and untwisted to about 19 base-pairs per turn. The bacteriophage T4 UvsX protein is only weakly homologous to RecA, but it has very similar ATP-dependent DNA binding and strand-exchange activities. We can now show that the UvsX protein forms helical filaments that are very similar to those made by RecA, and induces the same extended DNA conformation within these filaments that is induced by RecA. This implies that the unusual conformation of DNA in the RecA filament may be a universal structure in homologous recombination.
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1081
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Yu X, Matsuda Z, Yu QC, Lee TH, Essex M. Vpx of simian immunodeficiency virus is localized primarily outside the virus core in mature virions. J Virol 1993; 67:4386-90. [PMID: 8510227 PMCID: PMC237811 DOI: 10.1128/jvi.67.7.4386-4390.1993] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Human immunodeficiency virus type 2 and the related simian immunodeficiency virus (SIV) contain a unique regulatory gene, vpx. The Vpx protein is packaged in mature virions and is required for efficient viral replication in peripheral blood lymphocytes and macrophages. To study the localization of Vpx in mature virions, conical and bar-shaped core structures of SIV from macaques (SIVmac) were purified. The SIVmac core has a density of approximately 1.25 g/cm3, compared with 1.16 g/cm3 for an intact virion. The relative proportions of major capsid protein (p27) and reverse transcriptase activity were similar for intact virions and core structures. The majority of matrix protein (p14) was removed from the purified core structure, suggesting its association with the viral membrane. Similarly, most of the Vpx protein was absent from the purified core structure. This result suggests that as with the matrix protein, the majority of Vpx proteins are localized outside the virus core. The localization of Vpx suggests that it may be involved in virus entry such as penetration or uncoating.
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1082
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Yu X, Ma Q. [Fermentation of engineered strain producing cholera toxin B subunit]. WEI SHENG WU XUE BAO = ACTA MICROBIOLOGICA SINICA 1993; 33:177-81. [PMID: 8236951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Studies indicate that the cholera B subunit could be synthesized efficiently in corn steep liquor by engineered E. coli strain MM2. We have also determined the optical density, pH and the yield of B subunit kinetically during fermentation. Corn steep liquor medium has advantages in low cost, simplicity in technological process and high yield of B subunit which can reaches 40 micrograms/ml in 50L fermentative tank.
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1083
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Davis EL, Yu X, Joynt RB, Wieczkowski G, Giordano L. Shear strength and microleakage of light-cured glass ionomers. AMERICAN JOURNAL OF DENTISTRY 1993; 6:127-9. [PMID: 8240773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Bond to dentin and marginal integrity of three light activated glass ionomer cements were evaluated, and compared to a traditional chemical-cured glass ionomer cement. Results indicated no significant difference in shear bond strength among the glass ionomer cements tested. However, there was a significant difference among glass ionomer cements in bond strength variability, with coefficients of variation ranging from 55 to 102%. A discrepancy between manufacturers' instructions and optimum curing times is one possible explanation for these results. There were also no significant differences in microleakage among glass ionomer cements. Most samples exhibited minimal or no microleakage.
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1084
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Yu X, Wojciechowski M, Fenselau C. Assessment of metals in reconstituted metallothioneins by electrospray mass spectrometry. Anal Chem 1993; 65:1355-9. [PMID: 8517548 DOI: 10.1021/ac00058a010] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A method has been developed that combines electrospray ionization mass spectrometry with pH control to provide analysis of metals in native or reconstituted metallothioneins. These metalloproteins cooperatively bind seven divalent metal ions, most commonly Zn2+ and Cd2+. Since the protein is denatured and metal ions are lost below pH3, the pH of the electrospray solution is critical to successful results. The metal-free apoprotein was detected with its most abundant ions in a charge state of 6+, while the folded metallothionein-metal complexes were observed with lower charge states. The retention of seven metals in the molecular ions detected is consistent with the hypothesis that metallothionein retains its conformation in the gas phase. This mass spectrometric technique can be used to determine rapidly and accurately how many and what cations are incorporated per molecule of protein. Information about molar distributions and estimates of relative abundances of various complexes in the sample can be acquired in a single measurement.
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1085
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Yu X, Egelman EH. The LexA repressor binds within the deep helical groove of the activated RecA filament. J Mol Biol 1993; 231:29-40. [PMID: 8496964 DOI: 10.1006/jmbi.1993.1254] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The RecA protein of Escherichia coli, as a result of DNA damage, catalyzes the cleavage of its own repressor, the LexA protein, and thereby initiates the SOS response. Using a non-cleavable LexA mutant, we have obtained a co-complex of both the RecA and LexA proteins on DNA. Mass analysis using scanning transmission electron microscopy suggests that the site size of the LexA repressor on RecA is two, which would be consistent with a nearest-neighbor exclusion model for binding. Three-dimensional reconstruction of electron micrographs of these filaments shows that the LexA protein is bound in the deep groove of the RecA filament, with two strong regions of contact that span adjacent RecA protomers within the filament. One contact is consistent with a proposed LexA binding site in the RecA crystal structure. The other contact maps onto a region that has been postulated to be a second DNA-binding site within RecA, which can explain the inhibition of RecA cleavage of LexA by excess DNA.
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1086
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North WG, Yu X. Forms of neurohypophysial peptides generated by tumors, and factors regulating their expression. REGULATORY PEPTIDES 1993; 45:209-16. [PMID: 8390078 DOI: 10.1016/0167-0115(93)90208-p] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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1087
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Matsuda Z, Yu X, Yu QC, Lee TH, Essex M. A virion-specific inhibitory molecule with therapeutic potential for human immunodeficiency virus type 1. Proc Natl Acad Sci U S A 1993; 90:3544-8. [PMID: 7682710 PMCID: PMC46337 DOI: 10.1073/pnas.90.8.3544] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A potential new approach for gene therapy against human immunodeficiency virus type 1 (HIV-1) infection is the design of a nonstructural gene-based virion-specific inhibitory molecule that is packaged with virus to destroy its infectivity. We tested this approach for HIV-1 by using Vpx, a virion-associated protein of HIV-2 and simian immunodeficiency virus. Vpx was incorporated into HIV-1 virions and the resulting cell-free virus lost infectivity in CD4+ human T cells. This demonstrates the therapeutic potential of an accessory gene-based virion-specific inhibitory molecule. Vpx and its derivatives can be regarded as a new class of anti-HIV-1 molecule.
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1088
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Yu X, Carroll S, Rigaud JL, Inesi G. H+ countertransport and electrogenicity of the sarcoplasmic reticulum Ca2+ pump in reconstituted proteoliposomes. Biophys J 1993; 64:1232-42. [PMID: 8388268 PMCID: PMC1262440 DOI: 10.1016/s0006-3495(93)81489-9] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The Ca2+ transport adenosine triphosphatase of sarcoplasmic reticulum was reconstituted in unilamellar liposomes prepared by reverse-phase evaporation. The size of the resulting proteoliposomes was similar to that of native sarcoplasmic reticulum vesicles, but their protein content was much lower, with a protein/lipid ratio (wt/wt) of 1:40-160, as compared with 1:1 in the native membrane. The proteoliposomes sustained adenosine triphosphate-dependent Ca2+ uptake at rates proportional to the protein content (1-2 mumol Ca2+/mg protein/min), reaching asymptotic levels corresponding to a lumenal calcium concentration of 10-20 mM. The low permeability of the proteoliposomes permitted direct demonstration of Ca2+/H+ countertransport and electrogenicity by parallel measurements in the same experimental system. Countertransport of one H+ per one Ca2+ was demonstrated, and inhibition of the Ca2+ pump by lumenal alkalinization was relieved by the H+ ionophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone. Consistent with the countertransport stoichiometry, net positive charge displacement was produced by Ca2+ transport, as revealed by a rapid oxonol VI absorption rise. The initial rise and the following steady-state level of oxonol absorption were highest when SO4(2-) was the prevalent anion and lowest in the presence of the lipophilic anion SCN-. The influence of anions was attributed to potential driven counterion compensation. The absorption rise was rapidly collapsed by addition of valinomycin in the presence of K+. Experimentation with Ca2+ and H+ ionophores was consistent with a primary role of Ca2+ and H+ in net charge displacement. The estimated value of the steady-state electrical potential observed under optimal conditions was approximately 50 mV and was accounted for by the estimated charge transfer associated with Ca2+ and H+ countertransport under the same conditions.
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1089
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Ogawa T, Yu X, Shinohara A, Egelman EH. Similarity of the yeast RAD51 filament to the bacterial RecA filament. Science 1993; 259:1896-9. [PMID: 8456314 DOI: 10.1126/science.8456314] [Citation(s) in RCA: 521] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The RAD51 protein functions in the processes of DNA repair and in mitotic and meiotic genetic recombination in the yeast Saccharomyces cerevisiae. The protein has adenosine triphosphate-dependent DNA binding activities similar to those of the Escherichia coli RecA protein, and the two proteins have 30 percent sequence homology. RAD51 polymerized on double-stranded DNA to form a helical filament nearly identical in low-resolution, three-dimensional structure to that formed by RecA. Like RecA, RAD51 also appears to force DNA into a conformation of approximately a 5.1-angstrom rise per base pair and 18.6 base pairs per turn. As in other protein families, its structural conservation appears to be stronger than its sequence conservation. Both the structure of the protein polymer formed by RecA and the DNA conformation induced by RecA appear to be general properties of a class of recombination proteins found in prokaryotes as well as eukaryotes.
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1090
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Yu X, Reed BM. Improved shoot multiplication of mature hazelnut (Corylus avellana L.) in vitro using glucose as a carbon source. PLANT CELL REPORTS 1993; 12:256-259. [PMID: 24197152 DOI: 10.1007/bf00237130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/1992] [Revised: 12/11/1992] [Indexed: 06/02/2023]
Abstract
Shoot cultures established from mature trees of hazelnut (Corylus avellana L.) cvs. Nonpareil and Tonda Gentile Romana were used to determine the effects of basal media, carbon sources and concentrations, pH and cytokinins on shoot multiplication. All factors except pH affected the multiplication rate. Shoot multiplication was the best on a modified Driver and Kuniyuki medium for Paradox walnut (DKW) supplemented with 6-benzylaminopurine (BA) (1.5-3 mg/l). Plants grown on 3% glucose or fructose medium produced more and longer shoots than those on sucrose. The general appearance and growth habit of shoots were better on medium with glucose than fructose. 'Nonpareil' shoots elongated better than those of 'Tonda Gentile Romana.' Changes in medium pH from 4.7 to 5.7 did not significantly affect the multiplication rate. More than 10 genotypes propagated well on modified DKW medium with glucose. This is the first report of the effect of carbon sources on shoot multiplication of hazelnut and provides a basis for further research in the improvement of hazelnut micropropagation.
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1091
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Yu X, Chung M, Morabito MA, Barnstable CJ. Shared nuclear protein binding sites in the upstream region of the rat opsin gene. Biochem Biophys Res Commun 1993; 191:76-82. [PMID: 7916602 DOI: 10.1006/bbrc.1993.1186] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
DNase I protection and gel retardation assays have identified two sequences 5' to the rat opsin gene that interact with nuclear proteins from retina but not from a number of neuronal and non-neuronal tissues. These sites, Ret 2 and Ret 3, are over 1200 base pairs apart but seem to interact with the same protein(s). Synthetic oligonucleotides corresponding to each site were able to inhibit complex formation in a gel retardation assay using an oligonucleotide corresponding to the other site. The proteins binding to the Ret 2 and Ret 3 sites co-eluted in both ion exchange and gel filtration chromatography. The protein(s) were also present at adult levels at birth, suggesting that they may represent differentiation products expressed in the proliferating retinal epithelium.
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1092
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Doige CA, Yu X, Sharom FJ. The effects of lipids and detergents on ATPase-active P-glycoprotein. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1146:65-72. [PMID: 8095161 DOI: 10.1016/0005-2736(93)90339-2] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We previously isolated and characterized a partially purified preparation of ATPase-active P-glycoprotein, the multidrug transporter (Doige, C.A., Yu, X. and Sharom, F.J. (1992) Biochim. Biophys. Acta 1109, 149-160). The effect of various detergents and membrane phospholipids on the ATPase activity of P-glycoprotein has now been investigated. P-Glycoprotein ATPase activity was most stable in CHAPS, with over 50% of the activity retained at a concentration of 8 mM. Octyl glucoside in the low mM range also supported the ATPase, while deoxycholate destroyed all activity at 1 mM. Digitonin and SDS inhibited ATPase activity at very low concentrations. Triton X-100 at 2-10 microM stimulated the ATPase almost 2-fold, while higher levels inhibited activity. Although P-glycoprotein ATPase was sensitive to thermal inactivation, full activity was preserved in the presence of asolectin, but not phosphatidylcholine species. Further studies revealed that asolectin, both saturated and unsaturated phosphatidylethanolamines, and phosphatidylserine, were best able to maintain ATPase activity at 23 degrees C. Saturated phosphatidylethanolamine species activated P-glycoprotein ATPase up to 40% at 23 degrees C, and 80% at 4 degrees C. Following detergent delipidation, various lipids were able to restore P-glycoprotein ATPase activity. Unsaturated phosphatidylcholine and phosphatidylserine were most effective, while saturated species were not able to restore catalytic activity. These results indicate that membrane lipids are necessary for catalytic activity of the ATPase domains of P-glycoprotein. P-Glycoprotein has well-defined lipid preferences, with saturated phosphatidylethanolamines both activating the ATPase and providing protection from thermal inactivation, while fluid lipid mixtures are able to restore activity following delipidation.
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1093
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Jones CE, Beise EJ, Belz JE, Carr RW, Filippone BW, Lorenzon W, McKeown RD, Mueller BA, O'Neill TG, Dodson GW, Dow K, Farkhondeh M, Kowalski S, Lee K, Makins N, Milner R, Thompson A, Tieger D, Young A, Yu X, Zumbro JD. He-vector3(e-vectore') quasielastic asymmetry. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1993; 47:110-130. [PMID: 9968416 DOI: 10.1103/physrevc.47.110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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1094
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Yu X, Yuan X, McLane MF, Lee TH, Essex M. Mutations in the cytoplasmic domain of human immunodeficiency virus type 1 transmembrane protein impair the incorporation of Env proteins into mature virions. J Virol 1993; 67:213-21. [PMID: 8416370 PMCID: PMC237354 DOI: 10.1128/jvi.67.1.213-221.1993] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In-frame stop codons were introduced into the coding region of human immunodeficiency virus type 1 (HIV-1) transmembrane protein (gp41). Truncation of 147 amino acids from the carboxyl terminus of gp41 (TM709) significantly decreased the stability and cell surface expression of the viral Env proteins, while truncation of 104 amino acids (TM752) did not. Truncation of 43 or more amino acids from the carboxyl terminus of gp41 generated mutant viruses which were noninfectious in several human CD4+ T lymphoid cell lines and fresh peripheral blood mononuclear cells. Analysis of the noninfectious mutant virions revealed significantly reduced incorporation of the Env proteins compared with the wild-type virions. Comparable amounts of Env proteins were detected on the surfaces of wild-type- and TM752-transfected cells, suggesting that the structures of gp41 required for efficient incorporation of Env proteins were disrupted in mutant TM752. Truncation of the last 12 amino acids (TM844) from the carboxyl terminus of gp41 did not significantly affect the assembly and release of virions or the incorporation of Env proteins into mature virions. However, the TM844 virus had dramatically decreased infectivity compared with the wild-type virus. This suggests that the cytoplasmic domain of gp41 also plays a role in other steps of virus replication.
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1095
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Ogawa T, Shinohara A, Nabetani A, Ikeya T, Yu X, Egelman EH, Ogawa H. RecA-like recombination proteins in eukaryotes: functions and structures of RAD51 genes. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 1993; 58:567-76. [PMID: 7956071 DOI: 10.1101/sqb.1993.058.01.063] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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1096
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Yu X, Jin Y, Fan M, Xu G, Liu Q, Raoult D. Genotypic and antigenic identification of two new strains of spotted fever group rickettsiae isolated from China. J Clin Microbiol 1993; 31:83-8. [PMID: 8093253 PMCID: PMC262626 DOI: 10.1128/jcm.31.1.83-88.1993] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Four isolates of spotted fever group rickettsiae isolated from ticks in China were compared with all known species and strains of spotted fever group rickettsiae by immunofluorescence assay, DNA polymerase chain reaction followed by restriction endonuclease fragment length polymorphism analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western immunoblot. The Chinese isolates belonged to three types, including a novel serotype which has not been described before. One isolate obtained from tick ova of Dermacentor nuttallii in Inner Mongolia was antigenically and genotypically identical to Rickettsia sibirica. Two isolates obtained from Dermacentor sinicus collected from Beijing were identical, different from other members of spotted fever group rickettsiae but apparently closely related to R. sibirica. HA-91, a strain isolated from Hyalomma asiaticum bv. kozlovi olenew, was antigenically and genotypically unique among spotted fever group rickettsiae, and we feel that data presented here should prompt consideration of it as a new species on the basis of current rickettsial taxonomy.
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1097
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Inesi G, Cantilina T, Yu X, Nikic D, Sagara Y, Kirtley ME. Long-range intramolecular linked functions in activation and inhibition of SERCA ATPases. Ann N Y Acad Sci 1992; 671:32-47; discussion 48. [PMID: 1288328 DOI: 10.1111/j.1749-6632.1992.tb43782.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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1098
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Miller DE, Noble NA, Yu X, Border WA. Molecular and cellular biological techniques in the study of glomerular diseases. Semin Nephrol 1992; 12:506-15. [PMID: 1282274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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1099
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Doige CA, Yu X, Sharom FJ. ATPase activity of partially purified P-glycoprotein from multidrug-resistant Chinese hamster ovary cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1992; 1109:149-60. [PMID: 1355666 DOI: 10.1016/0005-2736(92)90078-z] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In vitro studies of multidrug-resistant cell lines have shown that a membrane protein, the P-glycoprotein, is responsible for resistance to a wide range of structurally and functionally dissimilar anti-cancer drugs. The amino-acid sequence of P-glycoprotein (Pgp) indicates two consensus sequences for ATP binding and the purified protein has been reported to possess a low level of ATPase activity. As part of our goal to further characterize the ATPase activity of P-glycoprotein, we have developed a procedure for rapid partial purification of the protein in a highly active form. Plasma membrane vesicles from multidrug-resistant CHRC5 Chinese hamster ovary cells were subjected to a two-step procedure involving selective extraction with different concentrations of the zwitterionic detergent CHAPS. The resulting extract was enriched in P-glycoprotein (around 30% pure) and displayed an ATPase activity (specific activity 543 nmol mg-1 min-1) that was not found in a similar preparation from drug-sensitive cells. The ATPase specific activity was over 10-fold higher than that previously reported for immunoprecipitated Pgp and 280-fold higher than that of immunoaffinity-purified Pgp. This ATPase activity could be distinguished from that of other ion-motive ATPases and membrane-associated phosphatases and is, thus, proposed to be directly attributable to P-glycoprotein. Optimal P-glycoprotein ATPase activity required Mg2+ at an ATP: Mg2+ molar ratio of 0.75:1 and the apparent Km for ATP was 0.88 mM. P-Glycoprotein ATPase could be completely inhibited by vanadate and by the sulfhydryl-modifying reagents N-ethylmaleimide, HgCl2 and p-chloromercuribenzenesulfonate. Certain drugs and chemosensitizers, including colchicine, progesterone, nifedipine, verapamil and trifluoperazine, produced up to 50% activation of P-glycoprotein ATPase activity.
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1100
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Yu X, Egelman EH. Structural data suggest that the active and inactive forms of the RecA filament are not simply interconvertible. J Mol Biol 1992; 227:334-46. [PMID: 1522597 DOI: 10.1016/0022-2836(92)90702-l] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have used electron microscopy to examine the two major conformational states of the helical filament formed by the RecA protein of Escherichia coli. The compressed filament, formed in the absence of a nucleotide cofactor either as a self-polymer or on a single-stranded DNA molecule, is characterized in solution by about 6.1 subunits per turn of a 76 A pitch helix, and appears to be inactive with respect to all RecA activity. The active state of the filament, formed with ATP or an ATP analog on either a single or double-stranded DNA substrate, has about 6.2 subunits per turn of a 94 A pitch helix. Measurements of the contour length of RecA-covered single-stranded DNA circles in ice, formed in the absence of nucleotide cofactor, indicate that each RecA subunit binds five bases, in contrast to the three bases or base-pairs per subunit in the active state. The different stoichiometries of DNA binding suggests that the two polymeric forms are not interconvertible, as has been suggested on biochemical grounds. A three-dimensional reconstruction of the inactive state shows the same general features as the 83 A pitch filament present in the RecA crystal. This structural similarity and the fact that the crystal does not contain ATP or DNA suggests that the crystal structure is more similar to the compressed filament than the active, extended filament.
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