1
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Omoda A, Matsumoto K, Yoshino KI, Tachibana M, Tsuboi T, Torii M, Ishino T, Iriko H. Skeleton binding protein 1 localizes to the Maurer's cleft and interacts with PfHSP70-1 and PfHSP70-x in Plasmodium falciparum gametocyte-infected erythrocytes. Parasitol Int 2024; 100:102864. [PMID: 38331312 DOI: 10.1016/j.parint.2024.102864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/01/2024] [Accepted: 02/03/2024] [Indexed: 02/10/2024]
Abstract
Plasmodium falciparum accounts for the majority of malaria deaths, due to pathology provoked by the ability of infected erythrocytes to adhere to vascular endothelium within deep tissues. The parasite recognizes endothelium by trafficking and displaying protein ligands on the surface of asexual stage infected erythrocytes, such as members of the large family of pathogenic proteins, P. falciparum erythrocyte membrane protein 1 (PfEMP1). Parasite-encoded skeleton binding protein 1 (SBP1) plays an important role in the transport of these binding-related surface proteins, via cleft-like membranous structures termed Maurer's clefts, which are present within the cytoplasm of infected erythrocytes. Erythrocytes infected with gametocyte stages accumulate in the extravascular compartment of bone marrow; and it was suggested that their surface-expressed adhesion molecule profile and protein trafficking mechanisms might differ from those in asexual stage parasites. Protein trafficking mechanisms via Maurer's clefts have been well investigated in asexual stage parasite-infected erythrocytes; but little is known regarding the gametocyte stages. In this study, we characterized SBP1 during gametocyte maturation and demonstrated that SBP1 is expressed and localizes to dot-like Maurer's cleft structures in the cytoplasm of gametocyte-infected erythrocytes. Co-immunoprecipitation and mass spectrometry assays indicated that SBP1 interacts with the molecular chaperones PfHSP70-1 and PfHSP70-x. Localization analysis suggested that some PfHSP70-1 and/or PfHSP70-x localize in a dot-like pattern within the cytoplasm of immature gametocyte-infected erythrocytes. These findings suggest that SBP1 may interact with HSP70 chaperones in the infected erythrocyte cytoplasm during the immature gametocyte stages.
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Affiliation(s)
- Ayaka Omoda
- Division of Global Infectious Diseases, Department of Public Health, Graduate School of Health Sciences, Kobe University, Kobe, Hyogo, Japan
| | - Konomi Matsumoto
- Faculty of Health Sciences, Kobe University School of Medicine, Kobe, Hyogo, Japan
| | | | - Mayumi Tachibana
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Toon, Ehime, Japan
| | - Takafumi Tsuboi
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Ehime, Japan
| | - Motomi Torii
- Division of Global Infectious Diseases, Department of Public Health, Graduate School of Health Sciences, Kobe University, Kobe, Hyogo, Japan; Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Toon, Ehime, Japan
| | - Tomoko Ishino
- Department of Parasitology and Tropical Medicine, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - Hideyuki Iriko
- Division of Global Infectious Diseases, Department of Public Health, Graduate School of Health Sciences, Kobe University, Kobe, Hyogo, Japan; Faculty of Health Sciences, Kobe University School of Medicine, Kobe, Hyogo, Japan.
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2
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Hidese R, Toyoda M, Yoshino KI, Fukuda W, Wihardja GA, Kimura S, Fujita J, Niitsu M, Oshima T, Imanaka T, Mizohata E, Fujiwara S. The C-terminal flexible region of branched-chain polyamine synthase facilitates substrate specificity and catalysis. FEBS J 2019; 286:3926-3940. [PMID: 31162806 DOI: 10.1111/febs.14949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 05/03/2019] [Accepted: 06/01/2019] [Indexed: 01/26/2023]
Abstract
Branched-chain polyamine synthase (BpsA) catalyzes sequential aminopropyl transfer from the donor, decarboxylated S-adenosylmethionine (dcSAM), to the acceptor, linear-chain polyamine, resulting in the production of a quaternary-branched polyamine via tertiary branched polyamine intermediates. Here, we analyzed the catalytic properties and X-ray crystal structure of Tth-BpsA from Thermus thermophilus and compared them with those of Tk-BpsA from Thermococcus kodakarensis, which revealed differences in acceptor substrate specificity and C-terminal structure between these two enzymes. To investigate the role of the C-terminal flexible region in acceptor recognition, a region (QDEEATTY) in Tth-BpsA was replaced with that in Tk-BpsA (YDDEESSTT) to create chimeric Tth-BpsA C9, which showed a severe reduction in catalytic efficiency toward N4 -aminopropylnorspermidine, but not toward N4 -aminopropylspermidine, mimicking Tk-BpsA substrate specificity. Tth-BpsA C9 Tyr346 and Thr354 contributed to discrimination between tertiary branched-chain polyamine substrates, suggesting that the C-terminal region of BpsA recognizes acceptor substrates. Liquid chromatography-tandem mass spectrometry analysis on a Tk-BpsA reaction mixture with dcSAM revealed two aminopropyl groups bound to two of five aspartate/glutamate residues (Glu339 , Asp342 , Asp343 , Glu344 , and Glu345 ) in the C-terminal flexible region. Mutating each of these five amino acid residues to asparagine/glutamine resulted in a slight decrease in activity. The quadruple mutant D342N/D343N/E344Q/E345Q exhibited a severe reduction in catalytic efficiency, suggesting that these aspartate/glutamate residues function to receive aminopropyl chains. In addition, the X-ray crystal structure of the Tk-BpsA ternary complex bound to N4 -bis(aminopropyl)spermidine revealed that Asp126 and Glu259 interacted with the aminopropyl moiety in N4 -aminopropylspermidine.
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Affiliation(s)
- Ryota Hidese
- Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, Sanda, Japan
| | - Masataka Toyoda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Japan
| | | | - Wakao Fukuda
- Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, Sanda, Japan
| | - Gita Adhirani Wihardja
- Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, Sanda, Japan
| | - Seigo Kimura
- Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, Sanda, Japan
| | - Junso Fujita
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Masaru Niitsu
- Faculty of Pharmacy and Pharmaceutical Sciences, Josai University, Sakado, Japan
| | - Tairo Oshima
- Institute of Environmental Microbiology, Kyowa-kako Co., Ltd, Machida, Japan
| | - Tadayuki Imanaka
- The Research Organization of Science & Technology, Ritsumeikan University, Kusatsu, Japan
| | - Eiichi Mizohata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Japan.,Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
| | - Shinsuke Fujiwara
- Department of Bioscience, Graduate School of Science and Technology, Kwansei-Gakuin University, Sanda, Japan
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3
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Chen M, Gan X, Yoshino KI, Kitakawa M, Shoji I, Deng L, Hotta H. Hepatitis C virus NS5A protein interacts with lysine methyltransferase SET and MYND domain-containing 3 and induces activator protein 1 activation. Microbiol Immunol 2017; 60:407-17. [PMID: 27080060 DOI: 10.1111/1348-0421.12383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/01/2016] [Accepted: 04/10/2016] [Indexed: 12/27/2022]
Abstract
Hepatitis C virus (HCV) non-structural protein 5A (NS5A) is a multifunctional protein that is involved in the HCV life cycle and pathogenesis. In this study, a host protein(s) interacting with NS5A by tandem affinity purification were searched for with the aim of elucidating the role of NS5A. An NS5A-interacting protein, SET and MYND domain-containing 3 (SMYD3), a lysine methyltransferase reportedly involved in the development of cancer, was identified. The interaction between NS5A and SMYD3 was confirmed in ectopically expressing, HCV RNA replicon-harboring and HCV-infected cells. The other HCV proteins did not bind to SMYD3. SMYD3 bound to NS5A of HCV genotypes 1b and 2a. Deletion mutational analysis revealed that domains II and III of NS5A (amino acids [aa] 250 to 447) and the MYND and N-SET domains of SMYD3 (aa 1 to 87) are involved in the full extent of NS5A-SMYD3 interaction. NS5A co-localized with SMYD3 exclusively in the cytoplasm, thereby inhibiting nuclear localization of SMYD3. Moreover, NS5A formed a complex with SMYD3 and heat shock protein 90 (HSP90), which is a positive regulator of SMYD3. The intensity of binding between SMYD3 and HSP90 was enhanced by NS5A. Luciferase reporter assay demonstrated that NS5A significantly induces activator protein 1 (AP-1) activity, this being potentiated by co-expression of SMYD3 with NS5A. Taken together, the present results suggest that NS5A interacts with SMYD3 and induces AP-1 activation, possibly by facilitating binding between HSP90 and SMYD3. This may be a novel mechanism of AP-1 activation in HCV-infected cells.
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Affiliation(s)
- Ming Chen
- Division of Microbiology.,Division of Infectious Disease Control, Kobe University Graduate School of Medicine
| | - Xiang Gan
- Division of Microbiology.,Institute of Biochemistry and Molecular Biology, Hubei University, Wuhan, China
| | | | | | - Ikuo Shoji
- Division of Infectious Disease Control, Kobe University Graduate School of Medicine
| | - Lin Deng
- Division of Microbiology.,Division of Infectious Disease Control, Kobe University Graduate School of Medicine
| | - Hak Hotta
- Division of Microbiology.,Department of Oral Vaccine and Drug Development, Kobe University Graduate School of Health Sciences, Kobe, Japan
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Kozel C, Thompson B, Hustak S, Moore C, Nakashima A, Singh CR, Reid M, Cox C, Papadopoulos E, Luna RE, Anderson A, Tagami H, Hiraishi H, Slone EA, Yoshino KI, Asano M, Gillaspie S, Nietfeld J, Perchellet JP, Rothenburg S, Masai H, Wagner G, Beeser A, Kikkawa U, Fleming SD, Asano K. Overexpression of eIF5 or its protein mimic 5MP perturbs eIF2 function and induces ATF4 translation through delayed re-initiation. Nucleic Acids Res 2016; 44:8704-8713. [PMID: 27325740 PMCID: PMC5062967 DOI: 10.1093/nar/gkw559] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/10/2016] [Indexed: 11/14/2022] Open
Abstract
ATF4 is a pro-oncogenic transcription factor whose translation is activated by eIF2 phosphorylation through delayed re-initiation involving two uORFs in the mRNA leader. However, in yeast, the effect of eIF2 phosphorylation can be mimicked by eIF5 overexpression, which turns eIF5 into translational inhibitor, thereby promoting translation of GCN4, the yeast ATF4 equivalent. Furthermore, regulatory protein termed eIF5-mimic protein (5MP) can bind eIF2 and inhibit general translation. Here, we show that 5MP1 overexpression in human cells leads to strong formation of 5MP1:eIF2 complex, nearly comparable to that of eIF5:eIF2 complex produced by eIF5 overexpression. Overexpression of eIF5, 5MP1 and 5MP2, the second human paralog, promotes ATF4 expression in certain types of human cells including fibrosarcoma. 5MP overexpression also induces ATF4 expression in Drosophila The knockdown of 5MP1 in fibrosarcoma attenuates ATF4 expression and its tumor formation on nude mice. Since 5MP2 is overproduced in salivary mucoepidermoid carcinoma, we propose that overexpression of eIF5 and 5MP induces translation of ATF4 and potentially other genes with uORFs in their mRNA leaders through delayed re-initiation, thereby enhancing the survival of normal and cancer cells under stress conditions.
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Affiliation(s)
- Caitlin Kozel
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | - Brytteny Thompson
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Samantha Hustak
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Chelsea Moore
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Akio Nakashima
- Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Chingakham Ranjit Singh
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Megan Reid
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Christian Cox
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Evangelos Papadopoulos
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Rafael E Luna
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Abbey Anderson
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Hideaki Tagami
- Graduate School of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan
| | - Hiroyuki Hiraishi
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Emily Archer Slone
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Ken-Ichi Yoshino
- Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Masayo Asano
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Sarah Gillaspie
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Jerome Nietfeld
- College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
| | - Jean-Pierre Perchellet
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Stefan Rothenburg
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Hisao Masai
- Genome Dynamics Project, Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Alexander Beeser
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Ushio Kikkawa
- Biosignal Research Center, Kobe University, Kobe 657-8501, Japan
| | - Sherry D Fleming
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Katsura Asano
- Molecular Cellular Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
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5
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Shirai Y, Morioka S, Sakuma M, Yoshino KI, Otsuji C, Sakai N, Kashiwagi K, Chida K, Shirakawa R, Horiuchi H, Nishigori C, Ueyama T, Saito N. Direct binding of RalA to PKCη and its crucial role in morphological change during keratinocyte differentiation. Mol Biol Cell 2011; 22:1340-52. [PMID: 21346190 PMCID: PMC3078077 DOI: 10.1091/mbc.e10-09-0754] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A small G protein, RalA, was identified as a binding partner of PKCη. The binding led to activation of RalA and actin depolymerization associated with keratinocyte differentiation. These results provide new insight into the molecular mechanism of cytoskeletal regulation that leads to drastic change of cell shape. During differentiation, keratinocytes undergo a dramatic shape change from small and round to large and flat, in addition to production of proteins necessary for the formation of epidermis. It has been shown that protein kinase C (PKC) η is crucial for keratinocyte differentiation. However, its role in this process has yet to be fully elucidated. Here, we show that catalytic activity is not necessary for enlarged and flattened morphology of human keratinocytes induced by overexpression of PKCη, although it is important for gene expression of the marker proteins. In addition, we identify the small G protein RalA as a binding partner of PKCη, which binds to the C1 domain, an indispensable region for the morphological change. The binding led activation of RalA and actin depolymerization associated with keratinocyte differentiation. siRNA techniques proved that RalA is involved in not only the keratinocyte differentiation induced by PKCη overexpression but also normal keratinocyte differentiation induced by calcium and cholesterol sulfate. These results provide a new insight into the molecular mechanism of cytoskeletal regulation leading to drastic change of cell shape.
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Affiliation(s)
- Yasuhito Shirai
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
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6
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Eguchi S, Oshiro N, Miyamoto T, Yoshino KI, Okamoto S, Ono T, Kikkawa U, Yonezawa K. AMP-activated protein kinase phosphorylates glutamine : fructose-6-phosphate amidotransferase 1 at Ser243 to modulate its enzymatic activity. Genes Cells 2008; 14:179-89. [PMID: 19170765 DOI: 10.1111/j.1365-2443.2008.01260.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutamine : fructose-6-phosphate amidotransferase 1 (GFAT1) was identified as a protein phosphorylated in glucose-deprived cells by immunoprecipitation using the anti-phospho Akt substrates (PAS) antibody, which recognizes the phosphorylation motif site by AMP-activated protein kinase (AMPK), followed by mass fingerprinting analysis. Glucose depletion-induced phosphorylation of endogenous GFAT was potentiated by 2-deoxyglucose (2-DG), an AMPK activator, and the 2-DG-stimulated phosphorylation of FLAG-tagged GFAT1 in transfected cells was suppressed by Compound C, an AMPK inhibitor. The 2-DG induced phosphorylation of GFAT1 was attenuated by the introduction of the kinase-negative mutant of AMPK, and the phosphorylation was observed in the cells expressing the constitutively active mutant of AMPK even in the absence of 2-DG. Subsequent analysis revealed that the PAS antibody recognized GFAT1 phosphorylated at Ser243, which is conserved among different species. The assay of the GFAT enzymatic activity in the cell lysates indicated that the 2-DG-treatment inhibited the enzymatic activity, and Compound C-preincubation partially prevented the 2-DG-induced decrease of the activity. Furthermore, the mutant replacing Ser243 by alanine partially prevented the decrease of GFAT activity by 2-DG treatment. These results indicate that the phosphorylation of GFAT1 at Ser243 by AMPK has an important role in the regulation of the GFAT1 enzymatic activity.
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Ohji G, Hidayat S, Nakashima A, Tokunaga C, Oshiro N, Yoshino KI, Yokono K, Kikkawa U, Yonezawa K. Suppression of the mTOR-raptor signaling pathway by the inhibitor of heat shock protein 90 geldanamycin. J Biochem 2007; 139:129-35. [PMID: 16428328 DOI: 10.1093/jb/mvj008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Heat shock protein 90 (Hsp90) was co-immunoprecipitated with raptor, the binding partner of the mammalian target of rapamycin (mTOR) from HEK293 cells. Hsp90 was detected in the anti-raptor antibody immunoprecipitates prepared from the cell extract by immunoblot analysis using the anti-Hsp90 antibody, and the association of these two proteins was confirmed by immunoprecipitation from the cells co-expressing Hsp90 and raptor as epitope-tagged molecules. Geldanamycin, a potent inhibitor of Hsp90, disrupted the in vivo binding of Hsp90 to raptor without affecting the association of raptor and mTOR, and suppressed the phosphorylation by mTOR of the downstream translational regulators p70 S6 kinase (S6K) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). The protein kinase activity of S6K as well as the phosphorylation of the substrate, 40S ribosomal protein S6, were lowered in the geldanamycin-treated cells. These results indicate that Hsp90 is involved in the regulation of protein translation by facilitating the phosphorylation reaction of 4E-BP1 and S6K catalyzed by the mTOR/raptor complex through the association with raptor, and that the mTOR signaling pathway is a novel target of geldanamycin.
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Affiliation(s)
- Goh Ohji
- Biosignal Research Center, Kobe University, Kobe 657-8501
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Iwasaki T, Sato KI, Yoshino KI, Itakura S, Kosuge K, Tokmakov AA, Owada K, Yonezawa K, Fukami Y. Phylogeny of Vertebrate Src Tyrosine Kinases Revealed by the Epitope Region of mAb327. ACTA ACUST UNITED AC 2006; 139:347-54. [PMID: 16567399 DOI: 10.1093/jb/mvj059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mass fingerprinting and MS/MS analysis demonstrated that Xyk, a 57-kDa Src family tyrosine kinase that is activated within minutes of Xenopus egg fertilization, comprises a mixture of two Src proteins, Src1 and Src2. However, the Xenopus Src protein, denoted as xSrc, is hardly detectable with mAb327, a universal Src-specific antibody, whose target sequence has not yet been determined. We show that a point amino acid substitution in the Src homology 3 domain of xSrc is critical for improvement of the low efficiency of its recognition by mAb327. Namely, a point-mutated xSrc, in which Arg-121 was replaced by His that is conserved among mAb327-reactive Src in mammals and chicken, showed increased recognition by mAb327. On the other hand, a mutant chicken Src, in which the His-122 residue is replaced by Arg, showed decreased recognition by mAb327. Genomic sequencing analysis also demonstrated that reptile Src proteins are of either the R-type (snake) or H-type (caiman, turtle, and tortoise). These studies revealed, for the first time, a critical amino acid in the Src SH3 domain for mAb327 recognition, and suggest a novel scheme for the molecular evolution of Src, in which the H-type Src(s) are monophyletic and derived from the R-type Src.
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Affiliation(s)
- Tetsushi Iwasaki
- Research Center for Environmental Genomics, Kobe University, Nada, Kobe 657-8501.
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9
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Taguchi K, Yoshinaka K, Yoshino KI, Yonezawa K, Maekawa S. Biochemical and morphologic evidence of the interaction of oligodendrocyte membrane rafts with actin filaments. J Neurosci Res 2005; 81:218-25. [PMID: 15931670 DOI: 10.1002/jnr.20555] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cytoskeletal structures under the cell membrane carry out pivotal roles in the maintenance and remodeling of the cell structures. Reforming of the cytoskeletal networks after partial extraction of membrane components could be a good clue to identify molecular components pertaining the interaction of cytoskeleton with membrane. A detergent extract from 3-week-old rat brain membrane fraction was found to make an actin-based gel upon incubation at 25 degrees C. Some protein components of the gelation products were recovered in a Triton-insoluble low-density microdomain fraction (raft) after depolymerization of actin filaments. Some of these proteins were identified as 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase), proteolipid protein (PLP), and myelin oligodendrocyte glycoprotein (MOG) through electrospray time-of-flight (ESI-TOF) analysis and Western blotting. Because these proteins are well-known marker proteins of oligodendrocytes, localization of these proteins and cholesterol, a raft-localized lipid, with actin filaments was studied using cultured oligodendrocytes. Clear colocalization of these proteins and cholesterol with actin filaments was observed after Triton treatment at 4 degrees C before fixation. These results indicate that raft microdomains participate in the formation of cell shape through interaction with microfilaments in oligodendrocytes.
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Affiliation(s)
- Katsutoshi Taguchi
- Division of Bioinformation, Department of Biosystems Science, Graduate School of Science and Technology, Kobe University, Nada-ku, Kobe, Japan
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Abstract
Although mTOR is a member of the PI-kinase-related kinase family, mTOR possesses serine-threonine protein kinase activities, which phosphorylate itself and exogenous substrates. mTOR autophosphorylates in vitro and is phosphorylated in vivo on serine residues. Ser2481, which is located in a His-Ser-Phe motif near the conserved carboxyl-terminal mTOR tail, has been reported as an autophosphorylation site in vivo and in vitro. The significance of the autophosphorylation remains unclear. Another phosphorylation site on mTOR in vivo is Ser2448. This site appears not to be an autophosphorylation site but a site potentially phosphorylated by protein kinase B (PKB). mTOR immunopurified from culture cells or tissues phosphorylates in vitro p70 S6 kinase (p70) alpha and p70beta, mainly on Thr412 or Thr401, respectively, located in a Phe-Thr-Tyr motif. Another exogenous substrate phosphorylated by immunopurified mTOR in vitro is eIF4E-binding protein 1 (4E-BP1) at sites corresponding to those phosphorylated in vivo during insulin stimulation in a Ser/Thr-Pro motif. Recently, raptor, a 150-kDa TOR-binding protein that contains a carboxyl-terminal WD-repeat domain, was discovered as a scaffold for the mTOR-catalyzed phosphorylation of 4E-BP1 and for the mTOR-mediated phosphorylation and activation of p70alpha. Other potential substrates phosphorylated by mTOR are nPKCdelta, nPKCepsilon, STAT3, and p53. The requirement of raptor for binding to and phosphorylation by mTOR of these potential substrates would clarify their physiological importance in the mTOR signaling pathway.
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Affiliation(s)
- K Yonezawa
- Biosignal Research Center, Kobe University, 657-8501, Kobe, Japan.
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Gan X, Kitakawa M, Yoshino KI, Oshiro N, Yonezawa K, Isono K. Tag-mediated isolation of yeast mitochondrial ribosome and mass spectrometric identification of its new components. Eur J Biochem 2002; 269:5203-14. [PMID: 12392552 DOI: 10.1046/j.1432-1033.2002.03226.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mitochondrial ribosomal proteins (mrps) of the budding yeast, Saccharomyces cerevisiae, have been extensively characterized genetically and biochemically. However, the list of the genes encoding individual mrps is still not complete and quite a few of the mrps are only predicted from their similarity to bacterial ribosomal proteins. We have constructed a yeast strain in which one of the small subunit proteins, termed Mrp4, was tagged with S-peptide and used for affinity purification of mitochondrial ribosome. Mass spectrometric analysis of the isolated proteins detected most of the small subunit mrps which were previously identified or predicted and about half of the large subunit mrps. In addition, several proteins of unknown function were identified. To confirm their identity further, we added tags to these proteins and analyzed their localization in subcellular fractions. Thus, we have newly established Ymr158w (MrpS8), Ypl013c (MrpS16), Ymr188c (MrpS17) and Ygr165w (MrpS35) as small subunit mrps and Img1, Img2, Ydr116c (MrpL1), Ynl177c (MrpL22), Ynr022c (MrpL50) and Ypr100w (MrpL51) as large subunit mrps.
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Affiliation(s)
- Xiang Gan
- Graduate School of Science and Technology, Department of Biology, Faculty of Science, and Biosignal Research Center, Kobe University, Japan
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Yoshino KI, Kajiura H, Nomura K, Takao T, Shimonishi Y, Kurita M, Yamaguchi M, Suzuki N. A halogenated amino acid-containing sperm activating peptide and its related peptides isolated from the egg jelly of sea urchins, Tripneustes gratilla, Pseudoboletia maculata, Strongylocentrotus nudus, Echinometra mathaei and Heterocentrotus mammillatus. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0305-0491(89)90159-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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