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Kashiwagi K, Pistocchi R, Shibuya S, Sugiyama S, Morikawa K, Igarashi K. Spermidine-preferential uptake system in Escherichia coli. Identification of amino acids involved in polyamine binding in PotD protein. J Biol Chem 1996; 271:12205-8. [PMID: 8647815 DOI: 10.1074/jbc.271.21.12205] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Spermidine-binding sites on PotD protein, substrate-binding protein in periplasm, in the spermidine-preferential uptake system in Escherichia coli were studied by measuring polyamine transport activities of right-side-out membrane vesicles with mutated PotD proteins prepared by site-directed mutagenesis of the potD gene and by measuring polyamine binding activities of these mutated PotD proteins. Polyamine transport activities of the mutated PotD proteins paralleled their polyamine binding activities. It was found that Trp-34, Thr-35, Glu-36, Tyr-37, Ser-83, Tyr-85, Asp-168, Glu-171, Trp-229, Trp-255, Asp-257, Tyr-293, and Gln-327 of PotD protein were involved in the binding to spermidine. When spermidine uptake activities were measured in intact cells expressing the mutated PotD proteins, it was found that Glu-171, Trp-255, and Asp-257 were more strongly involved in the binding of spermidine to PotD protein than the other amino acids listed above. The dissociation constants of spermidine for the mutated PotD proteins at Glu-171, Trp-255, and Asp-257 increased greatly in comparison with those for the other mutated PotD proteins. Since these three amino acids clearly interact with the diaminopropane moiety of spermidine, the results are in accordance with the finding that PotD protein has a higher affinity for spermidine than for putrescine. Putrescine was found to bind at the position of the diaminobutane moiety of spermidine.
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227
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Morita EH, Ohkubo T, Kuraoka I, Shirakawa M, Tanaka K, Morikawa K. Implications of the zinc-finger motif found in the DNA-binding domain of the human XPA protein. Genes Cells 1996; 1:437-42. [PMID: 9078375 DOI: 10.1046/j.1365-2443.1996.d01-252.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The XPA (xeroderma pigmentosum group A) protein specifically recognizes the UV-or chemically damaged DNA lesions, and triggers the nucleotide excision repair process. This XPA protein contains the functional domain which is crucial to the recognition of damaged DNA. Its primary structure suggests that this DNA binding domain may contain a zinc-finger motif. To gain a more detailed insight into this zinc-finger motif, we have measured the 113Cd-NMR spectra of the DNA binding domains derived from the wild-type and mutant XPA proteins. RESULTS 113Cd-NMR analysis, combined with atomic absorption and site-directed mutagenesis, revealed that the DNA binding domain contains one zinc ion, coordinated with four cysteine residues (Cys105, Cys108, Cys126, and Cys129), that is essential for correct protein folding in vivo and in vitro. CONCLUSIONS The four ligand cysteine residues form a Cys-X2-Cys-X17-Cys-X2-Cys motif, which is reminiscent of the (Cys)4 type zinc-finger motif found in numerous transcriptional regulatory proteins. However, the secondary structure prediction and the 3D-1D compatibility analysis demonstrate that there is no structural similarity in the vicinity of the zinc-finger motif between the XPA protein and other zinc-finger containing proteins. We conclude that the XPA protein contains a new type of zinc-finger motif.
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228
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Sugiyama S, Vassylyev DG, Matsushima M, Kashiwagi K, Igarashi K, Morikawa K. Crystal structure of PotD, the primary receptor of the polyamine transport system in Escherichia coli. J Biol Chem 1996; 271:9519-25. [PMID: 8621624 DOI: 10.1074/jbc.271.16.9519] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
PotD protein is a periplasmic binding protein and the primary receptor of the polyamine transport system, which regulates the polyamine content in Escherichia coli. The crystal structure of PotD in complex with spermidine has been solved at 2.5-A resolution. The PotD protein consists of two domains with an alternating beta-alpha-beta topology. The polyamine binding site is in a central cleft lying in the interface between the domains. In the cleft, four acidic residues recognize the three positively charged nitrogen atoms of spermidine, while five aromatic side chains anchor the methylene backbone by van der Waals interactions. The overall fold of PotD is similar to that of other periplasmic binding proteins, and in particular to the maltodextrin-binding protein from E. coli, despite the fact that sequence identity is as low as 20%. The comparison of the PotD structure with the two maltodextrin-binding protein structures, determined in the presence and absence of the substrate, suggests that spermidine binding rearranges the relative orientation of the PotD domains to create a more compact structure.
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229
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Kamada K, Ohsumi K, Horiuchi T, Shimamoto N, Morikawa K. Crystallization and preliminary X-ray analysis of the Escherichia coli replication terminator protein complexed with DNA. Proteins 1996; 24:402-3. [PMID: 8778788 DOI: 10.1002/(sici)1097-0134(199603)24:3<402::aid-prot14>3.0.co;2-q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Crystals of the Escherichia coli replication terminator protein (Tus) complexed with its binding site DNA were obtained by a microdialysis method using PEG 4000. They belong to the tetragonal space group P4(1)2(1)2 or P4(3)2(1)2 with the unit cell parameter: a = 68.1 A, c = 230.7 A and contain one protein-DNA complex in an asymmetric unit. The native data set has been collected to 2.7 A resolution.
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230
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Aoki KI, Morikawa K, Souma W, Sumi JI, Terao H. The Effectiveness of the Local Potential Approximation in the Wegner-Houghton Renormalization Group. ACTA ACUST UNITED AC 1996. [DOI: 10.1143/ptp.95.409] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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231
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Bocquet AE, Mizokawa T, Morikawa K, Fujimori A, Barman SR, Maiti K, Sarma DD, Tokura Y, Onoda M. Electronic structure of early 3d-transition-metal oxides by analysis of the 2p core-level photoemission spectra. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:1161-1170. [PMID: 9983572 DOI: 10.1103/physrevb.53.1161] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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232
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Kuraoka I, Morita EH, Saijo M, Matsuda T, Morikawa K, Shirakawa M, Tanaka K. Identification of a damaged-DNA binding domain of the XPA protein. Mutat Res 1996; 362:87-95. [PMID: 8538652 DOI: 10.1016/0921-8777(95)00038-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The XPA (xeroderma pigmentosum group A) protein is a zinc metalloprotein consisting of 273 amino acids which binds preferentially to UV- or chemical carcinogen-damaged DNA, suggesting that it is involved in the recognition of several types of DNA damage during nucleotide excision repair processes. Here we identify a DNA binding domain of the XPA protein. The region of the XPA protein responsible for preferential binding to DNA damaged by UV or cis-diammine-dichloroplatinum(II) (cisplatin) is contained within a truncated derivative of the XPA protein, MF122, consisting of 122 amino acids and containing a C4 type zinc finger motif. CD (circular dichroism) measurements of the MF122 protein showed that it has a helix-rich secondary structure, suggesting that it is a discretely folded, functional mini-domain. The MF122 protein should be useful for structural investigation of the XPA protein and of its interaction with damaged DNA.
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233
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Shimizu T, Morikawa K. The beta-prism: a new folding motif. Trends Biochem Sci 1996; 21:3-6. [PMID: 8848836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A new protein fold with internal symmetry has been observed in two proteins: vitelline membrane outer layer protein I (VMO-I) and delta-endotoxin. Despite lacking any discernible sequence similarity, both proteins have similar three-dimensional structures as well as a carbohydrate-binding site in the top region of the common fold.
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234
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Vassylyev DG, Kashiwagi T, Mikami Y, Ariyoshi M, Iwai S, Ohtsuka E, Morikawa K. Atomic model of a pyrimidine dimer excision repair enzyme complexed with a DNA substrate: structural basis for damaged DNA recognition. Cell 1995; 83:773-82. [PMID: 8521494 DOI: 10.1016/0092-8674(95)90190-6] [Citation(s) in RCA: 230] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
T4 endonuclease V is a DNA repair enzyme from bacteriophage T4 that catalyzes the first reaction step of the pyrimidine dimer-specific base excision repair pathway. The crystal structure of this enzyme complexed with a duplex DNA substrate, containing a thymine dimer, has been determined at 2.75 A resolution. The atomic structure of the complex reveals the unique conformation of the DNA duplex, which exhibits a sharp kink with a 60 degree inclination at the central thymine dimer. The adenine base complementary to the 5' side of the thymine dimer is completely flipped out of the DNA duplex and trapped in a cavity on the protein surface. These structural features allow an understanding of the catalytic mechanism and implicate a general mechanism of how other repair enzymes recognize damaged DNA duplexes.
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235
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Sakashita H, Sakuma T, Akitomo Y, Ohkubo T, Kainosho M, Sekiguchi M, Morikawa K. Sequence-specific DNA recognition of the Escherichia coli Ada protein associated with the methylation-dependent functional switch for transcriptional regulation. J Biochem 1995; 118:1184-91. [PMID: 8720133 DOI: 10.1093/oxfordjournals.jbchem.a125005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The Escherichia coli Ada protein, a suicidal DNA methyltransferase, is converted into a transcriptional regulator for methylation-resistance genes by the transfer of a methyl group from a DNA methylphosphotriester to its own Cys69 residue. Here, we report the DNA recognition mode and the functional switch mechanism of the N-terminal 16 kDa fragment of the Ada protein. NMR analysis has revealed that the segment from residues 102 to 123 forms a helix-turn-helix structure. A site-directed mutagenesis study has shown that the second helix in the helix-turn-helix structure plays a crucial role in specific recognition of DNA. These results imply that the sequence-specific interaction of the Ada protein with DNA occurs through the helix-turn-helix motif. NMR experiments on the methylated protein-DNA complex showed line broadening for the amide proton signals from the helix-turn-helix motif and for the protons in the vicinity of Cys69. In the case of the nonmethylated protein-DNA complex, signal broadening was observed only for protons from the helix-turn-helix. These findings suggest that the residues in the vicinity of Cys69 come into direct contact with the cognate DNA after methylation. We propose that the direct contact of this region is a major factor for the "switch" that converts the Ada protein from a nonspecific DNA binding form to a transcription factor.
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236
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Morikawa K, Mizokawa T, Kobayashi K, Fujimori A, Eisaki H, Uchida S, Iga F, Nishihara Y. Spectral weight transfer and mass renormalization in Mott-Hubbard systems SrVO3 and CaVO3: Influence of long-range Coulomb interaction. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:13711-13714. [PMID: 9980570 DOI: 10.1103/physrevb.52.13711] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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237
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Morikawa K, Togashi K, Minami S, Dodo Y, Imura T, Matsumoto M, Konishi J. MR and CT appearance of urethral clear cell adenocarcinoma in a woman. J Comput Assist Tomogr 1995; 19:1001-3. [PMID: 8537508 DOI: 10.1097/00004728-199511000-00032] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We present a case of clear cell adenocarcinoma of the female urethra that has been evaluated with CT and MRI. The lesion was a well-demarcated mass surrounded with peripheral enhancement on CT. On MRI a sharply marginated mass was located in the midurethra, giving rise to a smooth elevation of the bladder base. On T2-weighted imaging, the lesion was hyperintense, being surrounded by a ring of lower signal intensity at the periphery. A central urethral dot of lower signal intensity traversed the anterior one-third of the mass but was preserved in its entire length.
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Abstract
Elevated serum ferritin levels have been reported in a number of pathological states. These observations indicate that cells of the immune system can participate in the prevention of potential tissue toxicity from iron accumulation, and iron and iron-binding protein have important effects on immune systems. Ferritin is generally regarded as an intracellular iron storage protein. However, small amounts of ferritin circulate in the serum of normal individuals, and the physiological role of serum ferritin remains obscure. Although the function of ferritin is inevitably linked to iron metabolism, a role for ferritin in hematopoiesis and the immune system has drawn attention for years. Ferritin has an inhibitory effect on the in vitro growth of human hematopoietic progenitor cells and on the proliferation of T lymphocytes in vitro. Recently we report that ferritin may directly suppress the differentiation of human B lymphocytes maturing into antibody producing cells in vitro. In the present review, we summarise this field of research.
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239
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Saito A, Iwasaki H, Ariyoshi M, Morikawa K, Shinagawa H. Identification of four acidic amino acids that constitute the catalytic center of the RuvC Holliday junction resolvase. Proc Natl Acad Sci U S A 1995; 92:7470-4. [PMID: 7638215 PMCID: PMC41361 DOI: 10.1073/pnas.92.16.7470] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Escherichia coli RuvC protein is a specific endonuclease that resolves Holliday junctions during homologous recombination. Since the endonucleolytic activity of RuvC requires a divalent cation and since 3 or 4 acidic residues constitute the catalytic centers of several nucleases that require a divalent cation for the catalytic activity, we examined whether any of the acidic residues of RuvC were required for the nucleolytic activity. By site-directed mutagenesis, we constructed a series of ruvC mutant genes with similar amino acid replacements in 1 of the 13 acidic residues. Among them, the mutant genes with an alteration at Asp-7, Glu-66, Asp-138, or Asp-141 could not complement UV sensitivity of a ruvC deletion strain, and the multicopy mutant genes showed a dominant negative phenotype when introduced into a wild-type strain. The products of these mutant genes were purified and their biochemical properties were studied. All of them retained the ability to form a dimer and to bind specifically to a synthetic Holliday junction. However, they showed no, or extremely reduced, endonuclease activity specific for the junction. These 4 acidic residues, which are dispersed in the primary sequence, are located in close proximity at the bottom of the putative DNA binding cleft in the three-dimensional structure. From these results, we propose that these 4 acidic residues constitute the catalytic center for the Holliday junction resolvase and that some of them play a role in coordinating a divalent metal ion in the active center.
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Ohkubo T, Sakashita H, Morikawa K. [Structure and function of the Ada protein]. TANPAKUSHITSU KAKUSAN KOSO. PROTEIN, NUCLEIC ACID, ENZYME 1995; 40:1620-6. [PMID: 7568966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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241
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Morikawa K, Ariyoshi M, Vassylyev DG, Matsumoto O, Katayanagi K, Ohtsuka E. Crystal structure of a pyrimidine dimer-specific excision repair enzyme from bacteriophage T4: refinement at 1.45 A and X-ray analysis of the three active site mutants. J Mol Biol 1995; 249:360-75. [PMID: 7783199 DOI: 10.1006/jmbi.1995.0302] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Crystallographic study of bacteriophage T4 endonuclease V, which is involved in the initial step of the pyrimidine dimer-specific excision repair pathway, has been carried out with respect to the wild-type and three different mutant enzymes. This enzyme catalyzes the cleavage of the N-glycosyl bond at the 5'-side of the pyrimidine dimer, and subsequently incises the phosphodiester bond at the apyrimidinic site through a beta-elimination reaction. The structure of the wild-type enzyme refined at 1.45 A resolution reveals the detailed molecular architecture. The enzyme is composed of a single compact domain classified as an all-alpha structure. The molecule is stabilized mainly by three hydrophobic cores, two of which include many aromatic side-chain interactions. The structure has a unique folding motif, where the amino-terminal segment penetrates between two major alpha-helices and prevents their direct contact, and it is incompatible with the close-packing category of helices for protein folding. The concave surface, covered with many positive charges, implies an interface for DNA binding. The glycosylase catalytic center, which comprises Glu23 and the surrounding basic residues Arg3, Arg22 and Arg26, lie in this basic surface. The crystal structures of the three active-site mutants, in which Glu23 was replaced by Gln(E23Q) and Asp (E23D), respectively, and Arg3 by Gln (R3Q), have been determined at atomic resolution. The backbone structures of the E23Q and R3Q mutants were almost identical with that of the wild-type, while the E23D mutation induces a small, but significant, change in the backbone structure, such as an increase of the central kink of the H1 helix at Pro25. In the catalytic center of the glycosylase, however, these three mutations do not generate notable movements of protein atoms, except for significant shifts of some bound water molecules. Thus, the structural differences between the wild-type and each mutant are confined to the remarkably small region around their replaced chemical groups. Combined with the biochemical studies and the difference circular dichroism measurements, these results allow us to conclude that the negatively charged carboxyl group of Glu23 is essential for the cleavage of the N-glycosyl bond, and that the positively charged guanidino group of Arg3 is crucial to bind the substrate, a DNA duplex containing a pyrimidine dimer. The amino terminal alpha-amino group is located at a position approximately 4.4 A away from the carboxyl group of Glu23. These structural features are generally consistent with the reaction scheme proposed by Dodson and co-workers.
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Hiraoka M, Morikawa K, Hori C, Tsuchida S, Kasuga K, Tominaga T, Sudo M. Left renal pelvis of male neonates is predisposed to dilatation. ACTA PAEDIATRICA JAPONICA : OVERSEAS EDITION 1995; 37:352-4. [PMID: 7645386 DOI: 10.1111/j.1442-200x.1995.tb03328.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dilatation of the renal pelvis has been observed as an ultrasonographic finding of ureteral reflux as well as hydronephrosis. However, little information is available on the prevalence of renal pelvis at dilatation in neonates. We measured the inner pelvis dimension of the kidneys in 511 apparently healthy neonates (279 boys and 232 girls) using an ultrasound scanner to determine the prevalence of renal pelvis dilatation. Ninety per cent of the neonates had an inner dimension of both renal pelvises below 5 mm. The prevalence of left renal pelvis dilatation of 5 mm or more was significantly higher in the boys than in the girls, 25 (9%) compared to 5 (2%). In contrast, no significant difference was found in the prevalence of right renal pelvis dilatation between the sexes. In the boys, the prevalence of renal pelvis dilatation of 6 mm or more was significantly higher on the left side than on the right. Moreover, the left renal pelvis dilatation of the male neonates had a tendency to persist at 1 month of age. These findings suggest that the left renal pelvis of the baby boy may be predisposed to dilatation.
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Morikawa K, Oiwa K, Oseko F, Kubota T, Morikawa S, Nakamura T. Distinct effect of G-CSF on the growth and differentiation of myeloid progenitor cells from chronic idiopathic neutropenia. Intern Med 1995; 34:384-7. [PMID: 7544173 DOI: 10.2169/internalmedicine.34.384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Chronic idiopathic neutropenia (CIN) is a disorder characterized by severe neutropenia and a maturational arrest of the neutrophil precursors in the bone marrow. We examined the effect of recombinant human granulocyte-colony stimulating factor (rhG-CSF) on the growth and maturation of the myeloid progenitor cells from a patient with CIN. The patient's marrow cells showed poor colony forming activity, but a normal differentiating capacity to the stimulation with rhG-CSF, although they displayed a normal colony forming capacity in the presence of GM-CSF. Our observation indicates the distinct effect of rhG-CSF on the growth and maturation of the myeloid progenitors from a CIN patient.
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Nureki O, Vassylyev DG, Katayanagi K, Shimizu T, Sekine S, Kigawa T, Miyazawa T, Yokoyama S, Morikawa K. Architectures of class-defining and specific domains of glutamyl-tRNA synthetase. Science 1995; 267:1958-65. [PMID: 7701318 DOI: 10.1126/science.7701318] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The crystal structure of a class I aminoacyl-transfer RNA synthetase, glutamyl-tRNA synthetase (GluRS) from Thermus thermophilus, was solved and refined at 2.5 A resolution. The amino-terminal half of GluRS shows a geometrical similarity with that of Escherichia coli glutaminyl-tRNA synthetase (GlnRS) of the same subclass in class I, comprising the class I-specific Rossmann fold domain and the intervening subclass-specific alpha/beta domain. These domains were found to have two GluRS-specific, secondary-structure insertions, which then participated in the specific recognition of the D and acceptor stems of tRNA(Glu) as indicated by mutagenesis analyses based on the docking properties of GluRS and tRNA. In striking contrast to the beta-barrel structure of the GlnRS carboxyl-terminal half, the GluRS carboxyl-terminal half displayed an all-alpha-helix architecture, an alpha-helix cage, and mutagenesis analyses indicated that it had a role in the anticodon recognition.
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245
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Kawakami S, Togashi K, Kojima N, Morikawa K, Mori T, Konishi J. MR appearance of malignant lymphoma of the uterus. J Comput Assist Tomogr 1995; 19:238-42. [PMID: 7890849 DOI: 10.1097/00004728-199503000-00014] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE The uterus is rarely the initial site of malignant lymphoma. The purpose of this article is to present the MRI of malignant lymphoma of the uterus. MATERIALS AND METHODS Four cases with pathologically proven malignant lymphoma, in which the uterus was the only and the initial site of recognized visceral involvement, are presented; MRI was retrospectively evaluated. RESULTS All the lesions exhibited homogeneous hypointense signal on T1-weighted imaging and relatively hyperintense signal on T2-weighted imaging. One case exhibited diffuse and uniform enlargement of the uterine corpus and cervix in the presence of preserved endometrium and cervical epithelium. With these findings, a prospective diagnosis of lymphoma was feasible. The three other cases exhibited MR findings that closely resembled those of carcinoma of the cervix. However, in one case, preserved cervical epithelium in the presence of extensive involvement of the cervical stroma may have been a clue to the diagnosis of malignant lymphoma. Involvement of the vagina (three cases) and the urinary bladder (two cases) was clearly identified on MRI. CONCLUSION Lymphoma of the uterus exhibited various MR appearances; however, specific diagnosis might be feasible in limited cases. In addition, clear visualization of the extent of disease seen on MRI could contribute to clinical decisions about treatment.
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246
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Ishikawa M, Fujino T, Sakashita H, Morikawa K, Yamamoto T. Kinetic properties and structural characterization of highly purified acetyl-CoA synthetase from bovine heart and tissue distribution of the enzyme in rat tissues. TOHOKU J EXP MED 1995; 175:55-67. [PMID: 7610460 DOI: 10.1620/tjem.175.55] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Acetyl-CoA synthetase from bovine heart has been purified to homogeneity and been crystallized. The purification procedure involves ammonium sulfate precipitation and subsequent column chromatography on DEAE-Sepharose, Blue-Sepharose, CoA-Agarose and Superose 6. The purified enzyme has a specific activity of 45 units/mg protein, and its molecular weight estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis is approximately 72,000. The purified enzyme specifically utilizes acetate, ATP and CoA. Apparent Km values of the purified enzyme for acetate, CoA, and ATP were 0.16 mM, 0.14 mM and 0.25 mM, respectively. Limited digestion with trypsin, subtilisin BPN' and chymotrypsin revealed that the enzyme contains a 56 k segment resistant to these proteases. Secondary structure contents of the purified enzyme and the 56 k tryptic fragment were analyzed by circular dichroism measurement. The intact molecule contains 30% alpha-helix and 30% beta-structure, and trypsin digests alpha-helix rich regions more substantially. Western blot analysis of rat tissue homogenates by specific antibodies against the purified enzyme indicated that the 72 k enzyme is present in a wide variety of tissues and is most abundant in heart and kidney.
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247
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Kristensen O, Miyashita H, Vassylyev D, Tanaka F, Fujii I, Morikawa K. Crystallization and Preliminary X-ray Analysis: Transition State Complex of a Chloraphcnicol Prodrug Activitation Specific Catalytic. Protein Pept Lett 1994. [DOI: 10.2174/0929866501666220517221513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Fab fragment of an antibody with esterolytic activity has been crystallized as a complex with a transition state analog. Two crystal forms, both diffracting X-rays to a limiting resolution of 1.8 Å or better, proved to be
of a quality suitable for X-ray crystallographic studies. Data have been collected on both crystal forms in space group P2J with unit cell parameters: a= 55.9 Å, b= 61.7 Å, c= 66.67 Å and β= 104.7° for form I; a= 58.70 Å, b= 63.04 Å, c= 56.56 Å and β= 98.75° for form II. Both forms contain one molecule per asymmetric unit.
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Iwanaga Y, Kimura T, Miyashita N, Morikawa K, Nagata O, Itoh Z, Kondo Y. Characterization of acetylcholinesterase-inhibition by itopride. JAPANESE JOURNAL OF PHARMACOLOGY 1994; 66:317-22. [PMID: 7869618 DOI: 10.1254/jjp.66.317] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Itopride is a gastroprokinetic benzamide derivative. This agent inhibited both electric eel acetylcholinesterase (AChE) and horse serum butyrylcholinesterase (BuChE). The IC50 of itopride with AChE (2.04 +/- 0.27 microM) was, however, 100-fold less than that with BuChE, whereas in the case of neostigmine with AChE (11.3 +/- 3.4 nM), it was 10-fold less. The recovery of AChE activity inhibited by 10(-7) M neostigmine was partial, but that inhibited by up to 3 x 10(-5) M itopride was complete when the reaction mixture was subjected to ultrafiltration. Double reciprocal plots of the experimental data showed that both Km and Vmax were affected by itopride, suggesting that the inhibition is a "mixed" type, although primarily being an uncompetitive one. The inhibitory effect of itopride on cholinesterase (ChE) activity in guinea pig gastrointestine was much weaker than that on pure AChE. However, in the presence of a low dose of diisopropyl fluorophosphate, just enough to inhibit BuChE but not AChE, the IC50s of itopride against ChE activities were found to be about 0.5 microM. In conclusion, itopride exerts reversible and a "mixed" type of inhibition preferably against AChE. The IC50 of itopride for electric eel and guinea pig gastrointestinal AChE inhibition was 200 times and 50 times as large as that of neostigmine, respectively.
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Morikawa K, Oseko F, Morikawa S, Iwamoto K. Immunomodulatory effects of three macrolides, midecamycin acetate, josamycin, and clarithromycin, on human T-lymphocyte function in vitro. Antimicrob Agents Chemother 1994; 38:2643-7. [PMID: 7532933 PMCID: PMC188255 DOI: 10.1128/aac.38.11.2643] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The effect of three macrolide antibiotics, midecamycin acetate, josamycin, and clarithromycin, on human T-cell function was investigated in vitro. Midecamycin acetate and josamycin suppressed the proliferative response of peripheral blood mononuclear cells stimulated by polyclonal T-cell mitogens at concentrations between 1.6 and 8 micrograms/ml. At higher concentrations (40 to 200 micrograms/ml), all these drugs showed a marked inhibitory effect. At concentrations of 1.6 to 40 micrograms/ml, these drugs suppressed interleukin-2 (IL-2) production induced by mitogen-stimulated T cells, but not the expression of IL-2 receptor (CD25), in a dose-dependent manner. Therefore, the suppressive action on T-lymphocyte proliferation seems to be based on the ability of these drugs to inhibit IL-2 production by T cells. The drug also inhibited mixed lymphocyte reaction at the same concentrations. Combined treatment with these macrolides and the known immunosuppressants such as FK506 and cyclosporin A resulted in an increased inhibition of T-cell proliferation. The immunomodulatory properties of the antibiotics may have clinical relevance for modulation of the immune response in transplant patients and in patients with inflammatory diseases.
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Ariyoshi M, Vassylyev DG, Iwasaki H, Nakamura H, Shinagawa H, Morikawa K. Atomic structure of the RuvC resolvase: a holliday junction-specific endonuclease from E. coli. Cell 1994; 78:1063-72. [PMID: 7923356 DOI: 10.1016/0092-8674(94)90280-1] [Citation(s) in RCA: 240] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The crystal structure of the RuvC protein, a Holliday junction resolvase from E. coli, has been determined at 2.5 A resolution. The enzyme forms a dimer of 19 kDa subunits related by a dyad axis. Together with results from extensive mutational analyses, the refined structure reveals that the catalytic center, comprising four acidic residues, lies at the bottom of a cleft that nicely fits a DNA duplex. The structural features of the dimer, with a 30 A spacing between the two catalytic centers, provide a substantially defined image of the Holliday junction architecture. The folding topology in the vicinity of the catalytic site exhibits a striking similarity to that of RNAase H1 from E. coli.
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