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Urano T, Shiraki M, Usui T, Sasaki N, Ouchi Y, Inoue S. Identification of non-synonymous polymorphisms in the WDSOF1 gene as novel susceptibility markers for low bone mineral density in Japanese postmenopausal women. Bone 2010; 47:636-42. [PMID: 20601284 DOI: 10.1016/j.bone.2010.06.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 05/19/2010] [Accepted: 06/15/2010] [Indexed: 11/19/2022]
Abstract
Genetic factors are important for the development of osteoporosis. During the search for novel markers of single-nucleotide polymorphisms (SNPs) associated with bone mineral density (BMD) by performing a large-scale SNP screen with 251 Japanese postmenopausal women utilizing 50K SNP array, we here focused on the rs1370005 in the WD repeats and SOF1 domain-containing (WDSOF1) gene because we could found common non-synonymous variants in this WDSOF1 gene. The analysis of linkage disequilibrium (LD) in the WDSOF1 gene revealed that rs1370005 and 3 other non-synonymous SNPs (Arg47Ser, Pro108Leu and Ile194Val) lie in a 30-kb region of high LD. Quantitative real-time PCR (qRT-PCR) analysis showed that WDSOF1 mRNA was expressed in mouse primary osteoblasts and osteoclasts, suggesting that WDSOF1 plays some roles in the bone metabolism. We examined the 3 non-synonymous SNPs in WDSOF1 gene in 750 Japanese postmenopausal women. A trend test showed that Arg47Ser, Pro108Leu, and Ile194Val genotypes were significant associated with total body BMD (Arg47Ser; P=0.021, Pro108Leu; P=0.022 and Ile194Val; P=0.009). We also compared Z scores for total body BMD between the subjects bearing at least one minor allele and those lacking the minor allele using unpaired t test. Subjects with the one or two minor alleles had significantly lower Z scores for total body BMD (Arg47Ser; P=0.010, Pro108Leu; P=0.019 and Ile194Val; P=0.003). The present study suggests that these non-synonymous WDSOF1 polymorphisms play a role in the genetic susceptibility to osteoporosis.
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Affiliation(s)
- Tomohiko Urano
- Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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2
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Islas-Flores T, Guillén G, Islas-Flores I, Román-Roque CS, Sánchez F, Loza-Tavera H, Bearer EL, Villanueva MA. Germination behavior, biochemical features and sequence analysis of the RACK1/arcA homolog from Phaseolus vulgaris. PHYSIOLOGIA PLANTARUM 2009; 137:264-80. [PMID: 19832940 PMCID: PMC3376080 DOI: 10.1111/j.1399-3054.2009.01280.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Partial peptide sequence of a 36 kDa protein from common bean embryo axes showed 100% identity with a reported beta-subunit of a heterotrimeric G protein from soybean. Analysis of the full sequence showed 96.6% identity with the reported soybean G(beta)-subunit, 86% with RACK1B and C from Arabidopsis and 66% with human and mouse RACK1, at the amino acid level. In addition, it showed 85.5, 85 and 83% identities with arcA from Solanum lycopersicum, Arabidopsis (RACK1A) and Nicotiana tabacum, respectively. The amino acid sequence displayed seven WD40 domains and two sites for activated protein kinase C binding. The protein showed a constant expression level but the mRNA had a maximum at 32 h post-imbibition. Western immunoblotting showed the protein in vegetative plant tissues, and in both microsomal and soluble fractions from embryo axes. Synthetic auxin treatment during germination delayed the peak of RACK1 mRNA expression to 48 h but did not affect the protein expression level while the polar auxin transport inhibitor, naphtylphtalamic acid had no effect on either mRNA or protein expression levels. Southern blot and genomic DNA amplification revealed a small gene family with at least one member without introns in the genome. Thus, the RACK1/arcA homolog from common bean has the following features: (1) it is highly conserved; (2) it is both soluble and insoluble within the embryo axis; (3) it is encoded by a small gene family; (4) its mRNA has a peak of expression at the time point of germination stop and (5) its expression is only slightly affected by auxin but unaffected by an auxin transport blocker.
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Affiliation(s)
- Tania Islas-Flores
- Departamento de Biología Molecular de Plantas, Instituto de
Biotecnología, Universidad Nacional Autónoma de México,
UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Gabriel Guillén
- Departamento de Biología Molecular de Plantas, Instituto de
Biotecnología, Universidad Nacional Autónoma de México,
UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Ignacio Islas-Flores
- Centro de Investigacion Científica de Yucatán,
A.C., Unidad de Bioquímica y Biología Molecular de Plantas, Calle 43
No. 130, Col. Chuburná de Hidalgo, Mérida, Yucatán 97200,
Mexico
| | - Carolina San Román-Roque
- Departamento de Biología Molecular de Plantas, Instituto de
Biotecnología, Universidad Nacional Autónoma de México,
UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Federico Sánchez
- Departamento de Biología Molecular de Plantas, Instituto de
Biotecnología, Universidad Nacional Autónoma de México,
UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Herminia Loza-Tavera
- Facultad de Química, Departamento de Bioquímica,
Universidad Nacional Autónoma de México, UNAM, Ciudad Universitaria,
04510 DF, Mexico
| | - Elaine L. Bearer
- Department of Pathology and Laboratory Medicine, Brown University,
Providence, RI 02912, USA
| | - Marco A. Villanueva
- Departamento de Biología Molecular de Plantas, Instituto de
Biotecnología, Universidad Nacional Autónoma de México,
UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62250, Mexico
- Corresponding author,
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3
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Bromley EV, Taylor MC, Wilkinson SR, Kelly JM. The amino terminal domain of a novel WD repeat protein from Trypanosoma cruzi contains a non-canonical mitochondrial targeting signal. Int J Parasitol 2004; 34:63-71. [PMID: 14711591 DOI: 10.1016/j.ijpara.2003.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
WD (tryptophan/aspartic acid) repeat proteins perform a wide variety of functions in eukaryotic cells. They are characterised by the presence of a number of conserved repeat motifs that contribute to the beta-propeller structures which are the common feature of this large group of proteins. We report here the properties of the first characterised member of this family in the American trypanosome, Trypanosoma cruzi (TcBPP1). In the CL Brener clone the protein is 482 amino acids long and is predicted to contain four WD repeat motifs, flanked by amino and carboxyl terminal extensions. TcBPP1 is a single copy gene present on a 1.0/1.6 Mb pair of homologous chromosomes in a locus that is syntenic with the corresponding regions of Trypanosoma brucei and Leishmania major chromosomes. Consistent with the proposed hybrid nature of the CL Brener clone, the proteins encoded by the two different alleles share only 97% identity at the amino acid level. To determine subcellular location, we examined transfected parasites for the distribution of green fluorescent protein (GFP) fused with different regions of TcBPP1. These studies demonstrated that a 115 amino acid peptide derived from the amino terminal domain of TcBPP1 is able to target GFP to the mitochondrion. Interestingly this region lacks a typical amino terminal presequence suggesting that mitochondrial import is mediated by an alternative targeting signal.
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Affiliation(s)
- Elizabeth V Bromley
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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4
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Gori F, Divieti P, Demay MB. Cloning and characterization of a novel WD-40 repeat protein that dramatically accelerates osteoblastic differentiation. J Biol Chem 2001; 276:46515-22. [PMID: 11551928 DOI: 10.1074/jbc.m105757200] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bone morphogenetic proteins (BMPs) play a pivotal role in endochondral bone formation. Using differential display polymerase chain reaction, we have identified a novel gene, named BIG-3 (BMP-2-induced gene 3 kb), that is induced as a murine prechondroblastic cell line, MLB13MYC clone 17, acquires osteoblastic features in response to BMP-2 treatment. The 3-kilobase mRNA encodes a 34-kDa protein containing seven WD-40 repeats. Northern and Western analyses demonstrated that BIG-3 mRNA and protein were induced after 24 h of BMP-2 treatment. BIG-3 mRNA was expressed in conditionally immortalized murine bone marrow stromal cells, osteoblasts, osteocytes, and growth plate chondrocytes, as well as in primary calvarial osteoblasts. Immunohistochemistry demonstrated that BIG-3 was expressed in the osteoblasts of calvariae isolated from mouse embryos. To identify a role for BIG-3 in osteoblast differentiation, MC3T3-E1 cells were stably transfected with the full-length coding region of BIG-3 (MC3T3E1-BIG-3) cloned downstream of a cytomegalovirus promoter in pcDNA3.1. Pooled MC3T3E1-BIG-3 clones expressed alkaline phosphatase activity earlier and achieved a peak level of activity 10-fold higher than cells transfected with the empty vector (MC3T3E1-EV) at 14 days. Cyclic AMP production in response to parathyroid hormone was increased 10- and 14-fold at 7 and 14 days, respectively, in MC3T3E1-BIG-3 clones, relative to MC3T3E1-EV clones. This increase in cAMP production was associated with an increase in PTH binding. Expression of BIG-3 increased mRNA levels encoding Cbfa1, type I collagen, and osteocalcin and accelerated formation of mineralized nodules. In conclusion, we have identified a novel WD-40 protein, induced by BMP-2 treatment, that dramatically accelerates the program of osteoblastic differentiation in stably transfected MC3T3E1 cells.
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Affiliation(s)
- F Gori
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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5
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Lukowiak AA, Granneman S, Mattox SA, Speckmann WA, Jones K, Pluk H, Venrooij WJ, Terns RM, Terns MP. Interaction of the U3-55k protein with U3 snoRNA is mediated by the box B/C motif of U3 and the WD repeats of U3-55k. Nucleic Acids Res 2000; 28:3462-71. [PMID: 10982864 PMCID: PMC110750 DOI: 10.1093/nar/28.18.3462] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
U3 small nucleolar RNA (snoRNA) is a member of the Box C/D family of snoRNAs which functions in ribosomal RNA processing. U3-55k is a protein that has been found to interact with U3 but not other members of the Box C/D snoRNA family. We have found that interaction of the U3-55k protein with U3 RNA in vivo is mediated by the conserved Box B/C motif which is unique to U3 snoRNA. Mutation of Box B and Box C, but not of other conserved sequence elements, disrupted interaction of U3-55k with U3 RNA. Furthermore, a fragment of U3 containing only these two conserved elements was bound by U3-55k in vivo. RNA binding assays performed in vitro indicate that Box C may be the primary determinant of the interaction. We have cloned the cDNA encoding the Xenopus laevis U3-55k protein and find strong homology to the human sequence, including six WD repeats. Deletion of WD repeats or sequences near the C-terminus of U3-55k resulted in loss of association with U3 RNA and also loss of localization of U3-55k to the nucleolus, suggesting that protein-protein interactions contribute to the localization and RNA binding of U3-55k in vivo.
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Affiliation(s)
- A A Lukowiak
- Department of Biochemistry and Molecular Biology and Department of Genetics, University of Georgia, Life Science Building, Athens, GA 30602, USA
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6
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Strezoska Z, Pestov DG, Lau LF. Bop1 is a mouse WD40 repeat nucleolar protein involved in 28S and 5. 8S RRNA processing and 60S ribosome biogenesis. Mol Cell Biol 2000; 20:5516-28. [PMID: 10891491 PMCID: PMC86002 DOI: 10.1128/mcb.20.15.5516-5528.2000] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have identified and characterized a novel mouse protein, Bop1, which contains WD40 repeats and is highly conserved through evolution. bop1 is ubiquitously expressed in all mouse tissues examined and is upregulated during mid-G(1) in serum-stimulated fibroblasts. Immunofluorescence analysis shows that Bop1 is localized predominantly to the nucleolus. In sucrose density gradients, Bop1 from nuclear extracts cosediments with the 50S-80S ribonucleoprotein particles that contain the 32S rRNA precursor. RNase A treatment disrupts these particles and releases Bop1 into a low-molecular-weight fraction. A mutant form of Bop1, Bop1Delta, which lacks 231 amino acids in the N- terminus, is colocalized with wild-type Bop1 in the nucleolus and in ribonucleoprotein complexes. Expression of Bop1Delta leads to cell growth arrest in the G(1) phase and results in a specific inhibition of the synthesis of the 28S and 5.8S rRNAs without affecting 18S rRNA formation. Pulse-chase analyses show that Bop1Delta expression results in a partial inhibition in the conversion of the 36S to the 32S pre-rRNA and a complete inhibition of the processing of the 32S pre-rRNA to form the mature 28S and 5.8S rRNAs. Concomitant with these defects in rRNA processing, expression of Bop1Delta in mouse cells leads to a deficit in the cytosolic 60S ribosomal subunits. These studies thus identify Bop1 as a novel, nonribosomal mammalian protein that plays a key role in the formation of the mature 28S and 5.8S rRNAs and in the biogenesis of the 60S ribosomal subunit.
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MESH Headings
- Animals
- Cell Nucleolus/metabolism
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Mice
- Mutation
- RNA Precursors/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Ribosomal, 28S/genetics
- RNA, Ribosomal, 28S/metabolism
- RNA, Ribosomal, 5.8S/genetics
- RNA, Ribosomal, 5.8S/metabolism
- Repetitive Sequences, Amino Acid
- Ribonucleoproteins/genetics
- Ribonucleoproteins/metabolism
- Ribosomal Proteins/genetics
- Ribosomal Proteins/metabolism
- Ribosomes/genetics
- Ribosomes/metabolism
- Saccharomyces cerevisiae Proteins
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Affiliation(s)
- Z Strezoska
- Department of Molecular Genetics, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60607-7170, USA
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7
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Ayadi L, Callebaut I, Saguez C, Villa T, Mornon JP, Banroques J. Functional and structural characterization of the prp3 binding domain of the yeast prp4 splicing factor. J Mol Biol 1998; 284:673-87. [PMID: 9826507 DOI: 10.1006/jmbi.1998.2183] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nuclear pre-mRNA splicing occurs in a large RNA-protein complex containing four small nuclear ribonucleoprotein particles (snRNPs) and additional protein factors. The yeast Prp4 (yPrp4) protein is a specific component of the U4/U6 and U4/U6-U5 snRNPs, which associates transiently with the spliceosome before the first step of splicing. In this work, we used the in vivo yeast two-hybrid system and in vitro immunoprecipitation assays to show that yPrp4 interacts with yPrp3, another U4/U6 snRNP protein. To investigate the domain of yPrp4 that directly contacts yPrp3, we introduced deletions in the N-terminal half of yPrp4 and point mutations in the C-terminal half of the molecule, and we tested the resulting prp4 mutants for cell viability and for their ability to interact with yPrp3. We could not define any particular sequence in the first 161 amino acid residues that are specifically required for protein-protein interactions. However, deletion of a small basic-rich region of 30 amino acid residues is lethal to the cells. Analysis of the C terminus prp4 mutants obtained clearly shows that this region of yPrp4 represents the primary domain of interaction with yPrp3. Interestingly, yPrp4 shows significant similarity in its C-terminal half to the beta-subunits of G proteins. We have generated a three-dimensional computer model of this domain, consisting of a seven-bladed beta-propeller based on the crystalline structure of beta-transducin. Several lines of evidence suggested that yPrp4 is contacting yPrp3 through a large flat surface formed by the long variable loops linking the beta-strands of the propeller. This surface could be used as a scaffold for generating an RNA-protein complex.
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Affiliation(s)
- L Ayadi
- Centre de Génétique Moléculaire du CNRS, Laboratoire Propre Associé à l'Université P. & M. Curie, Gif-sur-Yvette, 91198, France
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8
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Taylor SS, Ha E, McKeon F. The human homologue of Bub3 is required for kinetochore localization of Bub1 and a Mad3/Bub1-related protein kinase. J Cell Biol 1998; 142:1-11. [PMID: 9660858 PMCID: PMC2133037 DOI: 10.1083/jcb.142.1.1] [Citation(s) in RCA: 323] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/1998] [Revised: 06/01/1998] [Indexed: 02/08/2023] Open
Abstract
A feedback control mechanism, or cell cycle checkpoint, delays the onset of anaphase until all the chromosomes are correctly aligned on the mitotic spindle. Previously, we showed that the murine homologue of Bub1 is not only required for checkpoint response to spindle damage, but also restrains progression through a normal mitosis (Taylor, S.S., and F. McKeon. 1997. Cell. 89:727-735). Here, we describe the identification of a human homologue of Bub3, a 37-kD protein with four WD repeats. Like Bub1, Bub3 localizes to kinetochores before chromosome alignment. In addition, Bub3 and Bub1 interact in mammalian cells. Deletion mapping was used to identify the domain of Bub1 required for binding Bub3. Significantly, this same domain is required for kinetochore localization of Bub1, suggesting that the role of Bub3 is to localize Bub1 to the kinetochore, thereby activating the checkpoint in response to unattached kinetochores. The identification of a human Mad3/Bub1-related protein kinase, hBubR1, which can also bind Bub3 in mammalian cells, is described. Ectopically expressed hBubR1 also localizes to kinetochores during prometaphase, but only when hBub3 is overexpressed. We discuss the implications of the common interaction between Bub1 and hBubR1 with hBub3 for checkpoint control.
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Affiliation(s)
- S S Taylor
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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9
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Johnstone RW, Wang J, Tommerup N, Vissing H, Roberts T, Shi Y. Ciao 1 is a novel WD40 protein that interacts with the tumor suppressor protein WT1. J Biol Chem 1998; 273:10880-7. [PMID: 9556563 DOI: 10.1074/jbc.273.18.10880] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Wilms tumor suppressor protein, WT1, is a transcription factor capable of activating or repressing transcription of various cellular genes. The mechanisms involved in regulating the transcriptional activities of WT1 are beginning to be unraveled. It appears that physical interactions of other cellular proteins (p53 and par-4) with WT1 can modulate the function of WT1. Here, we report the identification and cloning of a novel WT1-interacting protein termed Ciao 1, a member of the WD40 family of proteins. Ciao 1 specifically interacts with WT1 both in vitro and in vivo. This interaction alters the mobility of a WT1.DNA complex in gel shift assays, and results in a decrease in transcriptional activation mediated by WT1. Ciao 1 does not inhibit binding of WT1 to its consensus nucleotide sequence and does not affect the repression activity of WT1. Thus, Ciao 1 appears to specifically modulate the transactivation activity of WT1 and may function to regulate the physiological functions of WT1 in cell growth and differentiation.
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Affiliation(s)
- R W Johnstone
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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10
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Zhou Z, Reed R. Human homologs of yeast prp16 and prp17 reveal conservation of the mechanism for catalytic step II of pre-mRNA splicing. EMBO J 1998; 17:2095-106. [PMID: 9524131 PMCID: PMC1170554 DOI: 10.1093/emboj/17.7.2095] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pre-mRNA splicing takes place in two catalytic steps. The second step is poorly understood, especially in mammals. In yeast, the splicing factors, Prps 16, 17, 18 and Slu7 function exclusively in step II. Here we report the isolation of cDNAs encoding human Prps 16 and 17 which are 41 and 36% identical to their yeast counterparts. The Prp16 gene is essential in yeast, and we show that a chimeric yeast-human Prp16 protein rescues a yeast Prp16 knockout strain. Immunodepletion of hPrp16 from splicing extracts specifically blocks step II, and the activity can be fully restored with recombinant hPrp16. Moreover, both hPrps 16 and 17 associate with the spliceosome late in the splicing pathway. Mutations at the 3' splice site that specifically block step II do not affect the association of hPrps 16 and 17 with the spliceosome, indicating that these factors may function at a stage of step II prior to recognition of the 3' splice site. Recently, the human homologs of Prp18 and Slu7 were identified. The observation that humans contain homologs of all four known step II proteins in yeast indicates that the mechanism for catalytic step II is highly conserved.
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Affiliation(s)
- Z Zhou
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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11
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Heng HH, Wang A, Hu J. Mapping of the human HPRP3 and HPRP4 genes encoding U4/U6-associated splicing factors to chromosomes 1q21.1 and 9q31-q33. Genomics 1998; 48:273-5. [PMID: 9521884 DOI: 10.1006/geno.1997.5181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- H H Heng
- Biology Department, York University, North York, Ontario, Canada
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12
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DeSilva H, Lee K, Osley MA. Functional dissection of yeast Hir1p, a WD repeat-containing transcriptional corepressor. Genetics 1998; 148:657-67. [PMID: 9504914 PMCID: PMC1459821 DOI: 10.1093/genetics/148.2.657] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The HIR1 gene product is required to repress transcription of three of the four histone gene loci in Saccharomyces cerivisiae, and like its counterpart, the HIR2 protein, it functions as a transcriptional corepressor. Although Hir1p and Hir2p are physically associated in yeast, Hir1p is able to function independently of Hir2p when it is artificially recruited to the histone HTA1 promoter. A deletion analysis of HIR1 has revealed two separate repression domains: one in its N terminus, where seven copies of the beta-transducin or WD40 motif reside, and the second in the remaining C-terminal amino acids. Overexpression of the WD repeats in a hir1delta strain complemented its Hir- phenotype, while overexpression of the C terminus in a wild-type strain caused both Hir- and Spt- phenotypes. The Hir1p C terminus physically interacted in vivo with Hir2p, and both Hir1p repression domains interacted with full-length Hir1p. It was additionally found that the Hir1p WD repeats functionally interacted with the SPT4, SPT5, and SPT6 gene products, suggesting that these repeats may direct Hir1p to different protein complexes.
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Affiliation(s)
- H DeSilva
- Program in Molecular Biology, Sloan Kettering Cancer Center and Cornell University Graduate School of Medical Sciences, New York, New York 10021, USA
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13
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Pluk H, Soffner J, Lührmann R, van Venrooij WJ. cDNA cloning and characterization of the human U3 small nucleolar ribonucleoprotein complex-associated 55-kilodalton protein. Mol Cell Biol 1998; 18:488-98. [PMID: 9418896 PMCID: PMC121518 DOI: 10.1128/mcb.18.1.488] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The eukaryotic nucleolus contains a large number of small RNA molecules (snoRNAs) which, in the form of small nucleolar ribonucleoprotein complexes (snoRNPs), are involved in the processing and modification of pre-rRNA. The most abundant and one of the best-conserved snoRNAs is the U3 RNA. So far, only one human U3 snoRNA-associated protein, fibrillarin, has been characterized. Previously, the U3 snoRNPwas purified from CHO cells, and three proteins of 15, 50, and 55 kDa were found to copurify with the U3 snoRNA (B. Lübben, C. Marshallsay, N. Rottmann, and R. Lührmann, Nucleic Acids Res. 21:5377-5385, 1993). Here we report the cDNA cloning and characterization of the human U3 snoRNP-associated 55-kDa protein. The isolated cDNA codes for a novel nucleolar protein which is specifically associated with the U3 snoRNA. This protein, referred to as hU3-55k, is the first characterized U3 snoRNP-specific protein from humans. hU3-55k is a new member of the family of WD-40 repeat proteins and is conserved throughout evolution. It appears that the C-terminal end of hU3-55k is required for nucleolar localization and U3 snoRNA binding.
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Affiliation(s)
- H Pluk
- Department of Biochemistry, University of Nijmegen, The Netherlands
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14
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Thomas D, Kuras L, Barbey R, Cherest H, Blaiseau PL, Surdin-Kerjan Y. Met30p, a yeast transcriptional inhibitor that responds to S-adenosylmethionine, is an essential protein with WD40 repeats. Mol Cell Biol 1995; 15:6526-34. [PMID: 8524217 PMCID: PMC230905 DOI: 10.1128/mcb.15.12.6526] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A specific repression mechanism regulates the biosynthesis of sulfur amino acids in Saccharomyces cerevisiae. When the intracellular S-adenosylmethionine (AdoMet) concentration increases, transcription of the sulfur genes is repressed. Using a specific reporter system, we have isolated mutations impairing the AdoMet-mediated transcriptional regulation of the sulfur network. These mutations identified a new gene, MET30, and were shown to also affect the regulation of the methyl cycle. The MET30 gene was isolated and sequenced. Sequence analysis reveals that Met30p contains five copies of the WD40 motif within its carboxy-terminal part, like the yeast transcriptional repressors Hir1p and Tup1p. We identified one target of Met30p as Met4p, a transcriptional activator regulating the sulfate assimilation pathway. By the two-hybrid method, we showed that Met30p interacts with Met4p and identified a region of Met4p involved in this interaction. Further analysis reveals that expression of Met30p is essential for cell viability.
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Affiliation(s)
- D Thomas
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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15
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Lafontaine D, Tollervey D. Trans-acting factors in yeast pre-rRNA and pre-snoRNA processing. Biochem Cell Biol 1995; 73:803-12. [PMID: 8721996 DOI: 10.1139/o95-088] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The major intermediates in the pathway of pre-rRNA processing in yeast and other eukaryotes were originally identified by biochemical analyses. However, as a result of the analysis of the effects of mutations in trans-acting factors, the yeast pre-rRNA processing pathway is now characterized in far more detail than that of other eukaryotes. These analyses have led to the identification of processing sites and intermediates that were either too close in size or too short lived to detected by biochemical analyses alone. In addition, it was generally unclear whether pre-rRNA processing steps were endonucleolytic or exonucleolytic; analyses of trans-acting factors is now revealing a complex mixture of endonucleolytic and exonucleolytic processing steps. Many of the small nucleolar RNAs (snoRNAs) are excised from larger precursors. Analyses of trans-acting factors are also revealing details of pre-snoRNA processing in yeast. Interestingly, factors involved in pre-snoRNA processing turn out to be components that also function in pre-rRNA processing, suggesting a potential mechanism for the coregulation of rRNA and snoRNA synthesis. In general, very little is known about the regulation of pre-rRNA processing steps. The best candidate for a system regulating specific pre-rRNA processing reactions has recently been revealed by the analysis of a yeast pre-RNA methylase. Here we will review recent data on the trans-acting factors involved in yeast ribosome synthesis and discuss how these analyses have contributed to our current view of this complex process.
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Affiliation(s)
- D Lafontaine
- European Molecular Biology Laboratory (EMBL), Postfach 10 22 09, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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16
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Sathe SS, Harte PJ. The Drosophila extra sex combs protein contains WD motifs essential for its function as a repressor of homeotic genes. Mech Dev 1995; 52:77-87. [PMID: 7577677 DOI: 10.1016/0925-4773(95)00392-e] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Extra sex combs is a member of the Polycomb Group genes, whose products are required for stable long term transcriptional repression of the homeotic genes of the Bithorax and Antennapedia complexes. The Pc-G proteins are required to maintain the spatially restricted domains of homeotic gene expression established by the transiently expressed repressors, e.g., hunchback, but are not required for the functioning of these early repressors. This implies two distinct modes of repression and raises the question: how does the transition from early transient repression to stable Pc-G-mediated repression occur? While other Pc-G proteins are required continuously throughout development, the esc RNA is only present transiently in early embryos, suggesting that esc may play a role in mediating this transition to stable long term Pc-G-mediated repression. The predicted esc protein contains multiple copies of the WD motif, found in G-protein beta subunits as well as non-G proteins involved in diverse cellular functions, including transcriptional repression. The sequence alterations of a number of esc mutations cause amino acid substitutions within the WD repeats, identifying them as essential for the function of the esc protein as a repressor of homeotic gene expression. Other WD proteins are components of reversible macromolecular assemblies and the WD motif has recently been directly implicated in mediating interactions with other proteins in such complexes. We propose that the esc protein is similarly involved in the initial recruitment of Pc-G repressors to the homeotic genes to establish their stable long term repression.
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Affiliation(s)
- S S Sathe
- Department of Genetics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4955, USA
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17
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Brown JA, Bharathi A, Ghosh A, Whalen W, Fitzgerald E, Dhar R. A mutation in the Schizosaccharomyces pombe rae1 gene causes defects in poly(A)+ RNA export and in the cytoskeleton. J Biol Chem 1995; 270:7411-9. [PMID: 7706287 DOI: 10.1074/jbc.270.13.7411] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A collection of fission yeast Schizosaccharomyces pombe conditional mutants was screened for defective nucleocytoplasmic transport of poly(A)+ RNA by fluorescence in situ hybridization. We identified a temperature-sensitive mutant that accumulated poly(A)+ RNA in the nucleus and have named it rae1-1, for ribonucleic acid export. All rae1-1 cells exhibit the defect in poly(A)+ RNA export within 30 min following a shift to the non-permissive temperature. In addition, in the rae1-1 mutant, actin and tubulin become disorganized, and cells undergo an irreversible cycle arrest. Results from experiments in which rae1-1 cells were arrested in various phases of the cell division cycle and then shifted to nonpermissive temperature suggest that cells are particularly vulnerable to loss of rae1 function during G2/M. However, the inability to export RNA from the nucleus to the cytoplasm was not limited to a particular phase of the cell division cycle. The rae1 gene was isolated by complementation and encodes a predicted protein of 352 amino acids with four beta-transducin/WD40 repeats.
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Affiliation(s)
- J A Brown
- Laboratory of Molecular Virology, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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18
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19
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Mechler BM. When the control is lacking—the role of tumour suppressor genes in cancer development. J Biosci 1994. [DOI: 10.1007/bf02703201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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20
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Ma H. GTP-binding proteins in plants: new members of an old family. PLANT MOLECULAR BIOLOGY 1994; 26:1611-1636. [PMID: 7858207 DOI: 10.1007/bf00016493] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Regulatory guanine nucleotide-binding proteins (G proteins) have been studied extensively in animal and microbial organisms, and they are divided into the heterotrimeric and the small (monomeric) classes. Heterotrimeric G proteins are known to mediate signal responses in a variety of pathways in animals and simple eukaryotes, while small G proteins perform diverse functions including signal transduction, secretion, and regulation of cytoskeleton. In recent years, biochemical analyses have produced a large amount of information on the presence and possible functions of G proteins in plants. Further, molecular cloning has clearly demonstrated that plants have both heterotrimeric and small G proteins. Although the functions of the plant heterotrimeric G proteins are yet to be determined, expression analysis of an Arabidopsis G alpha protein suggests that it may be involved in the regulation of cell division and differentiation. In contrast to the very few genes cloned thus far that encode heterotrimeric G proteins in plants, a large number of small G proteins have been identified by molecular cloning from various plants. In addition, several plant small G proteins have been shown to be functional homologues of their counterparts in animals and yeasts. Future studies using a number of approaches are likely to yield insights into the role plant G proteins play.
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Affiliation(s)
- H Ma
- Cold Spring Harbor Laboratory, NY 11724
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21
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Molecular characterization of the 77-kDa echinoderm microtubule-associated protein. Homology to the beta-transducin family. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)31763-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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22
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Moore MS, Blobel G. Purification of a Ran-interacting protein that is required for protein import into the nucleus. Proc Natl Acad Sci U S A 1994; 91:10212-6. [PMID: 7937864 PMCID: PMC44988 DOI: 10.1073/pnas.91.21.10212] [Citation(s) in RCA: 270] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Previously we reported the isolation of two cytosolic fractions (A and B) from Xenopus ovary that are required sequentially to support protein import into the nuclei of digitonin-permeabilized cells. Fraction A is required for recognition of the nuclear localization sequence and targeting to the nuclear envelope, whereas fraction B is required for the subsequent translocation of the bound substrate into the nucleus. The first protein required for fraction B activity to be purified was the small GTPase Ran (ras-related nuclear protein). Here we report the purification of the second (and final) protein required for fraction B activity. By SDS/PAGE, the purified protein appeared as a single band with an apparent molecular mass of 10 kDa, but the native protein fractionated upon gel filtration chromatography with an apparent size of 30 kDa. Peptide sequence analysis indicated that the purified protein was highly homologous to a previously identified human protein of unknown function called placental protein 15 (pp15) and to the predicted protein product of a yeast open reading frame from Saccharomyces cerevisiae.
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Affiliation(s)
- M S Moore
- Laboratory of Cell Biology, Howard Hughes Medical Institute, Rockefeller University, New York, NY 10021
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23
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Yeast beta- and beta'-coat proteins (COP). Two coatomer subunits essential for endoplasmic reticulum-to-Golgi protein traffic. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)51110-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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24
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Mallet L, Bussereau F, Jacquet M. Nucleotide sequence analysis of an 11.7 kb fragment of yeast chromosome II including BEM1, a new gene of the WD-40 repeat family and a new member of the KRE2/MNT1 family. Yeast 1994; 10:819-31. [PMID: 7975899 DOI: 10.1002/yea.320100612] [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: 01/28/2023] Open
Abstract
This paper reports the DNA sequence and analysis of an 11.7 kb segment localized on the right arm of Saccharomyces cerevisiae chromosome II. This fragment contains one incomplete and five long and non-overlapping open reading frames (ORFs) designated from centromere to telomere-proximal side as: YBR1406, 1409, 1410, 1411, 1412 and 1413. YBR1406 corresponds to the 5' end to PG11 encoding phosphoglucoisomerase. YBR1410 encodes a polypeptide of 798 amino acids whose C terminus contains five repeats (WD-40 repeat) similar to those found in the beta-subunits of G proteins and different yeast proteins such as Tup1, Prp4 and Cdc4. The higher similarity score is obtained with dTAFII80, a component of the RNA polymerase II transcriptional complex TFIID. YBR1411 encodes a polypeptide of 464 amino acids which belongs to the family of alpha-mannosyltransferases: KRE2/MNT1, KTR1, KTR2, YUR1 and the product of previously sequenced ORF YBR1445. YBR1412 corresponds to BEM1. The two ORFs, YBR1409 and YBR1413, which do not exhibit significant similarity with any known coding sequences, define new genes.
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Affiliation(s)
- L Mallet
- Institut de Génétique et Microbiologie, URA1354 du CNRS, Orsay, France
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25
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A novel mammalian protein, p55CDC, present in dividing cells is associated with protein kinase activity and has homology to the Saccharomyces cerevisiae cell division cycle proteins Cdc20 and Cdc4. Mol Cell Biol 1994. [PMID: 7513050 DOI: 10.1128/mcb.14.5.3350] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel protein, p55CDC, has been identified in cycling mammalian cells. This transcript is readily detectable in all exponentially growing cell lines but disappears when cells are chemically induced to fall out of the cell cycle and differentiate. The p55CDC protein appears to be essential for cell division, since transfection of antisense p55CDC cDNA into CHO cells resulted in isolation of only those cells which exhibited a compensatory increase in p55CDC transcripts in the sense orientation. Immunoprecipitation of p55CDC yielded protein complexes with kinase activity which fluctuated during the cell cycle. Since p55CDC does not have the conserved protein kinase domains, this activity must be due to one or more of the associated proteins in the immune complex. The highest levels of protein kinase activity were seen with alpha-casein and myelin basic protein as substrates and demonstrated a pattern of activity distinct from that described for the known cyclin-dependent cell division kinases. The p55CDC protein was also phosphorylated in dividing cells. The amino acid sequence of p55CDC contains seven repeats homologous to the beta subunit of G proteins, and the highest degree of homology in these repeats was found with the Saccharomyces cerevisiae Cdc20 and Cdc4 proteins, which have been proposed to be involved in the formation of a functional bipolar mitotic spindle in yeast cells. The G beta repeat has been postulated to mediate protein-protein interactions and, in p55CDC, may modulate its association with a unique cell cycle protein kinase. These findings suggest that p55CDC is a component of the mammalian cell cycle mechanism.
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26
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Hu J, Xu Y, Schappert K, Harrington T, Wang A, Braga R, Mogridge J, Friesen JD. Mutational analysis of the PRP4 protein of Saccharomyces cerevisiae suggests domain structure and snRNP interactions. Nucleic Acids Res 1994; 22:1724-34. [PMID: 8202378 PMCID: PMC308056 DOI: 10.1093/nar/22.9.1724] [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
The PRP4 protein of Saccharomyces cerevisiae is an essential part of the U4/U6 snRNP, a component of the mRNA splicing apparatus. As an approach to the determination of structure-function relationships in the PRP4 protein, we have isolated more than fifty new alleles of the PRP4 gene through random and site-directed mutagenesis, and have analyzed the phenotypes of many of them. Twelve of the fourteen single-point mutations that give rise to temperature-sensitive (ts) or null phenotypes are located in the portion of the PRP4 gene that corresponds to the beta-transducin-like region of the protein; the remaining two are located in the central portion of the gene, one of them in an arginine-lysine-rich region. Nine additional deletion or deletion/insertion mutations were isolated at both the amino- and carboxy-termini. These data show that the amino-terminal region (108 amino acids) of PRP4 is non-essential, while the carboxy-terminal region is essential up to the penultimate amino acid. A deletion of one entire beta-transducin-like repeat (the third of five) resulted in a null phenotype. All ts mutants show a first-step defect in the splicing of U3 snRNA primary transcript in vivo at the non-permissive temperature. The effects on prp4 mutant growth of increased copy-number of mutant prp4 genes themselves, and of genes for other components of the U4/U6 snRNP (PRP3 and U6 snRNA) have also been studied. We suggest that the PRP4 protein has at least three domains: a non-essential amino-terminal segment of at least 108 amino acids, a central basic region of about 140 residues that is relatively refractile to mutation and might be involved in RNA interaction, and an essential carboxy-terminal region of about 210 residues with the five repeat-regions that are similar to beta-transducins, which might be involved in protein-protein interaction. A model of interactions of snRNP components suggested by these results is presented.
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Affiliation(s)
- J Hu
- Department of Medical Genetics, University of Toronto, Ontario, Canada
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27
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Weinstein J, Jacobsen FW, Hsu-Chen J, Wu T, Baum LG. A novel mammalian protein, p55CDC, present in dividing cells is associated with protein kinase activity and has homology to the Saccharomyces cerevisiae cell division cycle proteins Cdc20 and Cdc4. Mol Cell Biol 1994; 14:3350-63. [PMID: 7513050 PMCID: PMC358701 DOI: 10.1128/mcb.14.5.3350-3363.1994] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A novel protein, p55CDC, has been identified in cycling mammalian cells. This transcript is readily detectable in all exponentially growing cell lines but disappears when cells are chemically induced to fall out of the cell cycle and differentiate. The p55CDC protein appears to be essential for cell division, since transfection of antisense p55CDC cDNA into CHO cells resulted in isolation of only those cells which exhibited a compensatory increase in p55CDC transcripts in the sense orientation. Immunoprecipitation of p55CDC yielded protein complexes with kinase activity which fluctuated during the cell cycle. Since p55CDC does not have the conserved protein kinase domains, this activity must be due to one or more of the associated proteins in the immune complex. The highest levels of protein kinase activity were seen with alpha-casein and myelin basic protein as substrates and demonstrated a pattern of activity distinct from that described for the known cyclin-dependent cell division kinases. The p55CDC protein was also phosphorylated in dividing cells. The amino acid sequence of p55CDC contains seven repeats homologous to the beta subunit of G proteins, and the highest degree of homology in these repeats was found with the Saccharomyces cerevisiae Cdc20 and Cdc4 proteins, which have been proposed to be involved in the formation of a functional bipolar mitotic spindle in yeast cells. The G beta repeat has been postulated to mediate protein-protein interactions and, in p55CDC, may modulate its association with a unique cell cycle protein kinase. These findings suggest that p55CDC is a component of the mammalian cell cycle mechanism.
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Affiliation(s)
- J Weinstein
- Amgen, Inc., Thousand Oaks, California 91320
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28
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Kumar S, Matsuzaki T, Yoshida Y, Noda M. Molecular cloning and biological activity of a novel developmentally regulated gene encoding a protein with beta-transducin-like structure. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)78128-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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29
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Takahashi Y, Ishida S, Nagata T. Function and modulation of expression of auxin-regulated genes. INTERNATIONAL REVIEW OF CYTOLOGY 1994; 152:109-44. [PMID: 8206702 DOI: 10.1016/s0074-7696(08)62555-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Y Takahashi
- Department of Biology, Faculty of Science, University of Tokyo, Japan
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30
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Weinstat-Saslow DL, Germino GG, Somlo S, Reeders ST. A transducin-like gene maps to the autosomal dominant polycystic kidney disease gene region. Genomics 1993; 18:709-11. [PMID: 8307582 DOI: 10.1016/s0888-7543(05)80380-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A novel human gene (sazD) that maps to the autosomal dominant polycystic kidney disease region shares sequence similarity with members of the beta-transducin superfamily. The cDNA sazD-c predicts an approximately 58-kDa protein (sazD) with seven internal repeats, similar to the WD-40 motif of the transducin family. The size of this protein family has been expanding rapidly; however, neither the structure nor the function of this repeated motif is known. Preliminary data do not suggest that sazD is mutated in patients with polycystic kidney disease.
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Affiliation(s)
- D L Weinstat-Saslow
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
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31
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Harter C, Draken E, Lottspeich F, Wieland FT. Yeast coatomer contains a subunit homologous to mammalian beta'-COP. FEBS Lett 1993; 332:71-3. [PMID: 8405452 DOI: 10.1016/0014-5793(93)80487-f] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The homologue of the mammalian coatomer complex was isolated from yeast cytosol and separated on a modified urea-containing SDS-polyacrylamide gel system. An additional band in the 100 kDa molecular weight range appeared when compared to the protein pattern obtained in conventional Laemmli gels, exactly as observed for mammalian coatomer. Cross-reactivity with an anti-peptide antibody raised against the C-terminus of beta'-COP from bovine, and N-terminal sequence analysis, revealed that this protein from yeast is related to beta'-COP from mammals.
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Affiliation(s)
- C Harter
- Institute of Biochemistry I, University of Heidelberg, Germany
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32
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33
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Saccharomyces cerevisiae cdc15 mutants arrested at a late stage in anaphase are rescued by Xenopus cDNAs encoding N-ras or a protein with beta-transducin repeats. Mol Cell Biol 1993. [PMID: 8393141 DOI: 10.1128/mcb.13.8.4953] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have constructed a Xenopus oocyte cDNA library in a Saccharomyces cerevisiae expression vector and used this library to isolate genes that can function in yeast cells to suppress the temperature sensitive [corrected] defect of the cdc15 mutation. Two maternally expressed Xenopus cDNAs which fulfill these conditions have been isolated. One of these clones encodes Xenopus N-ras. In contrast to the yeast RAS genes, Xenopus N-ras rescues the cdc15 mutation. Moreover, overexpression of Xenopus N-ras in S. cerevisiae does not activate the RAS-cyclic AMP (cAMP) pathway; rather, it results in decreased levels of intracellular cAMP in both mutant cdc15 and wild-type cells. Furthermore, we show that lowering cAMP levels is sufficient to allow cells with a nonfunctional Cdc15 protein to complete the mitotic cycle. These results suggest that a key step of the cell cycle is dependent upon a phosphorylation event catalyzed by cAMP-dependent protein kinase. The second clone, beta TrCP (beta-transducin repeat-containing protein), encodes a protein of 518 amino acids that shows significant homology to the beta subunits of G proteins in its C-terminal half. In this region, beta Trcp is composed of seven beta-transducin repeats. beta TrCP is not a functional homolog of S. cerevisiae CDC20, a cell cycle gene that also contains beta-transducin repeats and suppresses the cdc15 mutation.
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34
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Spevak W, Keiper BD, Stratowa C, Castañón MJ. Saccharomyces cerevisiae cdc15 mutants arrested at a late stage in anaphase are rescued by Xenopus cDNAs encoding N-ras or a protein with beta-transducin repeats. Mol Cell Biol 1993; 13:4953-66. [PMID: 8393141 PMCID: PMC360138 DOI: 10.1128/mcb.13.8.4953-4966.1993] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We have constructed a Xenopus oocyte cDNA library in a Saccharomyces cerevisiae expression vector and used this library to isolate genes that can function in yeast cells to suppress the temperature sensitive [corrected] defect of the cdc15 mutation. Two maternally expressed Xenopus cDNAs which fulfill these conditions have been isolated. One of these clones encodes Xenopus N-ras. In contrast to the yeast RAS genes, Xenopus N-ras rescues the cdc15 mutation. Moreover, overexpression of Xenopus N-ras in S. cerevisiae does not activate the RAS-cyclic AMP (cAMP) pathway; rather, it results in decreased levels of intracellular cAMP in both mutant cdc15 and wild-type cells. Furthermore, we show that lowering cAMP levels is sufficient to allow cells with a nonfunctional Cdc15 protein to complete the mitotic cycle. These results suggest that a key step of the cell cycle is dependent upon a phosphorylation event catalyzed by cAMP-dependent protein kinase. The second clone, beta TrCP (beta-transducin repeat-containing protein), encodes a protein of 518 amino acids that shows significant homology to the beta subunits of G proteins in its C-terminal half. In this region, beta Trcp is composed of seven beta-transducin repeats. beta TrCP is not a functional homolog of S. cerevisiae CDC20, a cell cycle gene that also contains beta-transducin repeats and suppresses the cdc15 mutation.
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Affiliation(s)
- W Spevak
- Ernst Boehringer Institute, Vienna, Austria
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35
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Affiliation(s)
- J D Beggs
- Institute of Cell and Molecular Biology, University of Edinburgh, UK
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36
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Mallo M, Franco del Amo F, Gridley T. Cloning and developmental expression of Grg, a mouse gene related to the groucho transcript of the Drosophila Enhancer of split complex. Mech Dev 1993; 42:67-76. [PMID: 8369224 DOI: 10.1016/0925-4773(93)90099-j] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Genes of the Enhancer of split complex are involved in neural-epidermal cell fate decisions during early embryogenesis in Drosophila. One of these genes, the product of the Enhancer of split m9/10 or groucho transcript, encodes a ubiquitous nuclear protein with homology at the carboxy-terminus to G-protein beta-subunits. Here we describe the cloning and RNA expression analysis of a mouse gene, designated Grg, that is homologous to just the amino-terminal region of the groucho product. Grg encodes a 197 amino acid protein that shares 53% amino acid identity with the corresponding region of the product of the Drosophila groucho gene. However, the mouse Grg protein does not contain the region homologous to G-protein beta-subunits. An analysis by in situ hybridization of the spatial and temporal localization of Grg RNA expression revealed that, while the initial pattern of Grg expression was quite restricted, by midgestation Grg RNA was ubiquitously expressed in the developing embryo. Widespread Grg RNA expression was maintained in adult mice. The implications of these results for the existence of separable functional domains of the Drosophila groucho product, and possible roles of the Grg gene during mouse development, are discussed.
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Affiliation(s)
- M Mallo
- Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110
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37
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Dynlacht BD, Weinzierl RO, Admon A, Tjian R. The dTAFII80 subunit of Drosophila TFIID contains beta-transducin repeats. Nature 1993; 363:176-9. [PMID: 8483503 DOI: 10.1038/363176a0] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A key component of the RNA polymerase II transcriptional apparatus, TFIID, is a multi-protein complex containing the TATA box-binding protein (TBP) and at least seven tightly associated factors (TAFs). Although the functions of most TFIID subunits are unknown, it is clear that TAFs are not necessary for basal activity but that one or more are required for regulated transcription, and so behave as coactivators. The presence of multiple subunits indicates that there is an intricate assembly process and that TAFs may be responsible for other activities. We have described the properties of the subunit dTAFII110, which can interact directly with the transcriptional activator Sp1 (ref. 5). In addition, the largest subunit, dTAFII250, binds directly to TBP and links other TAFs to the complex. Here we describe the cloning, expression and partial characterization of the Drosophila TAF of M(r) 80,000, dTAFII80. Sequence analysis reveals that dTAFII80 contains several copies of the WD40 (beta-transducin) repeat. Moreover, dTAFII80 shares extended sequence similarity with an Arabidopsis gene, COP1, which encodes a putative transcription factor that is though to regulate development. We have expressed recombinant dTAFII80 and begun to characterize its interaction with other members of the TFIID complex. Purified recombinant dTAFII80 is unable to bind TBP directly or to interact strongly with the C-terminal domain of dTAFII250 (delta N250). Instead, dTAFII80 is only able to recognize and interact with a higher-order complex containing TBP, delta N250, 110 and 60. These findings suggest the formation of TFIID may require an ordered assembly of the TAFs, some of which bind directly to TBP and others that are tethered to the complex as a result of specific TAF/TAF interactions.
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Affiliation(s)
- B D Dynlacht
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720
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38
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Pryer NK, Salama NR, Schekman R, Kaiser CA. Cytosolic Sec13p complex is required for vesicle formation from the endoplasmic reticulum in vitro. J Cell Biol 1993; 120:865-75. [PMID: 8432727 PMCID: PMC2200066 DOI: 10.1083/jcb.120.4.865] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The SEC13 gene of Saccharomyces cerevisiae is required in vesicle biogenesis at a step before or concurrent with the release of transport vesicles from the ER membrane. SEC13 encodes a 33-kD protein with sequence homology to a series of conserved internal repeat motifs found in beta subunits of heterotrimeric G proteins. The product of this gene, Sec13p, is a cytosolic protein peripherally associated with membranes. We developed a cell-free Sec13p-dependent vesicle formation reaction. Sec13p-depleted membranes and cytosol fractions were generated by urea treatment of membranes and affinity depletion of a Sec13p-dihydrofolate reductase fusion protein, respectively. These fractions were unable to support vesicle formation from the ER unless cytosol containing Sec13p was added. Cytosolic Sec13p fractionated by gel filtration as a large complex of about 700 kD. Fractions containing the Sec13p complex restored activity to the Sec13p- dependent vesicle formation reaction. Expression of SEC13 on a multicopy plasmid resulted in overproduction of a monomeric form of Sec13p, suggesting that another member of the complex becomes limiting when Sec13p is overproduced. Overproduced, monomeric Sec13p was inactive in the Sec13p-dependent vesicle formation assay.
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Affiliation(s)
- N K Pryer
- Department of Molecular and Cell Biology, University of California, Berkeley 94720
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39
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Mirabito PM, Morris NR. BIMA, a TPR-containing protein required for mitosis, localizes to the spindle pole body in Aspergillus nidulans. J Cell Biol 1993; 120:959-68. [PMID: 8432735 PMCID: PMC2200070 DOI: 10.1083/jcb.120.4.959] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The Aspergillus nidulans bimA gene is required for mitosis. Loss of function mutations in bimA cause cells to arrest growth with condensed chromatin and a short, metaphaselike mitotic spindle. bimA is a member of a gene family defined by a repeated motif called the Tetratrico Peptide Repeat (TPR), which is found in genes from bacteria, yeast and insects. Several yeast TPR genes are also required for mitosis, including Saccharomyces cerevisiae CDC27 and Schizosaccharomyces pombe nuc2+, which appear to be functional homologs of bimA. We have developed antisera specific to the bimA protein (BIMA) and have characterized BIMA by western blot and immunocytochemical analyses. BIMA is heterogeneous in apparent molecular weight, consisting of a major 90-kD species and at least two minor species of approximately 105 kD. The results of BIMA localization by immunofluorescence microscopy depend on the level of BIMA expression. Overexpression of BIMA, which had no deleterious affect on growth or mitosis, resulted in localization of BIMA on or throughout most nuclei. Nuclear staining was granular, and overlapped but was not completely coincident with DNA staining by DAPI. In contrast, when expressed at normal levels, BIMA colocalized with the spindle pole body (SPB). BIMA localized to the SPB in a cell cycle independent manner. These results show that BIMA is either associated with or is a component of the SPB, and they suggest that BIMA functions at the spindle poles to promote the onset of anaphase.
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Affiliation(s)
- P M Mirabito
- Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854-5635
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40
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Characterization of HIR1 and HIR2, two genes required for regulation of histone gene transcription in Saccharomyces cerevisiae. Mol Cell Biol 1993. [PMID: 8417331 DOI: 10.1128/mcb.13.1.28] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The products of the HIR1 and HIR2 genes have been defined genetically as repressors of histone gene transcription in S. cerevisiae. A mutation in either gene affects cell cycle regulation of three of the four histone gene loci; transcription of these loci occurs throughout the cell cycle and is no longer repressed in response to the inhibition of DNA replication. The same mutations also eliminate autogenous regulation of the HTA1-HTB1 locus by histones H2A and H2B. The HIR1 and HIR2 genes have been isolated, and their roles in the transcriptional regulation of the HTA1-HTB1 locus have been characterized. Neither gene encodes an essential protein, and null alleles derepress HTA1-HTB1 transcription. Both HIR genes are expressed constitutively under conditions that lead to repression or derepression of the HTA1 gene, and neither gene regulates the expression of the other. The sequence of the HIR1 gene predicts an 88-kDa protein with three repeats of a motif found in the G beta subunit of retinal transducin and in a yeast transcriptional repressor, Tup1. The sequence of the HIR2 gene predicts a protein of 98 kDa. Both gene products contain nuclear targeting signals, and the Hir2 protein is localized in the nucleus.
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41
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Matsumoto Y, Sarkar G, Sommer SS, Wickner RB. A yeast antiviral protein, SKI8, shares a repeated amino acid sequence pattern with beta-subunits of G proteins and several other proteins. Yeast 1993; 9:43-51. [PMID: 8442386 DOI: 10.1002/yea.320090106] [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: 01/30/2023] Open
Abstract
SKI8 is a yeast antiviral gene, essential for controlling the propagation of M double-stranded RNA (dsRNA) and thus for preventing virus-induced cytopathology. Our DNA sequence of SKI8 shows that it encodes a 397 amino acid protein containing two copies of a 31 amino acid repeat pattern first identified in mammalian beta-transducin and Cdc4p of yeast. There are also four copies of this repeat in yeast Mak11p, necessary for M dsRNA propagation, and three copies in the putative product of the Dictyostelium AAC3 gene. Analysis of 36 cases of the repeat unit shows they have a consensus predicted structure: N-helix-sheet-turn-sheet-turn-sheet-helix-C.
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Affiliation(s)
- Y Matsumoto
- Section on Genetics of Simple Eukaryotes, National Institute of Diabetes, Digestive and Kidney Diseases, N.I.H., Bethesda, MD 20892
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42
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Sherwood PW, Tsang SV, Osley MA. Characterization of HIR1 and HIR2, two genes required for regulation of histone gene transcription in Saccharomyces cerevisiae. Mol Cell Biol 1993; 13:28-38. [PMID: 8417331 PMCID: PMC358881 DOI: 10.1128/mcb.13.1.28-38.1993] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The products of the HIR1 and HIR2 genes have been defined genetically as repressors of histone gene transcription in S. cerevisiae. A mutation in either gene affects cell cycle regulation of three of the four histone gene loci; transcription of these loci occurs throughout the cell cycle and is no longer repressed in response to the inhibition of DNA replication. The same mutations also eliminate autogenous regulation of the HTA1-HTB1 locus by histones H2A and H2B. The HIR1 and HIR2 genes have been isolated, and their roles in the transcriptional regulation of the HTA1-HTB1 locus have been characterized. Neither gene encodes an essential protein, and null alleles derepress HTA1-HTB1 transcription. Both HIR genes are expressed constitutively under conditions that lead to repression or derepression of the HTA1 gene, and neither gene regulates the expression of the other. The sequence of the HIR1 gene predicts an 88-kDa protein with three repeats of a motif found in the G beta subunit of retinal transducin and in a yeast transcriptional repressor, Tup1. The sequence of the HIR2 gene predicts a protein of 98 kDa. Both gene products contain nuclear targeting signals, and the Hir2 protein is localized in the nucleus.
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Affiliation(s)
- P W Sherwood
- Program in Molecular Biology, Sloan Kettering Cancer Center, New York, New York
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43
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Deng XW, Matsui M, Wei N, Wagner D, Chu AM, Feldmann KA, Quail PH. COP1, an Arabidopsis regulatory gene, encodes a protein with both a zinc-binding motif and a G beta homologous domain. Cell 1992; 71:791-801. [PMID: 1423630 DOI: 10.1016/0092-8674(92)90555-q] [Citation(s) in RCA: 360] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Plant seedling development is capable of following 1 of 2 distinct morphogenic pathways: skotomorphogenesis in darkness and photomorphogenesis in light. Dark-grown Arabidopsis seedlings with recessive mutations at the constitutively photomorphogenic (COP1) locus indicate that the wild-type COP1 protein represses photomorphogenesis in darkness and that light reverses this repressive activity. Using a T-DNA-tagged mutant, we have cloned the COP1 locus. The amino-terminal half of the encoded protein contains a conserved zinc-binding motif, whereas the carboxyl-terminal half contains a domain homologous to the WD-40 repeat motif of G beta proteins. The presence of both a putative DNA-binding motif and a G protein-related domain in a single polypeptide suggests that COP1 may be the first of a new class of regulatory molecules. This novel structure could endow COP1 with the capacity to function as a negative transcriptional regulator capable of direct interaction with components of the G protein signaling pathway.
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Affiliation(s)
- X W Deng
- University of California, Berkeley, United States Department of Agriculture Plant Gene Expression Center, Albany 94710
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44
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45
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Forney J, Rodkey K. A repetitive DNA sequence in Paramecium macronuclei is related to the beta subunit of G proteins. Nucleic Acids Res 1992; 20:5397-402. [PMID: 1437557 PMCID: PMC334347 DOI: 10.1093/nar/20.20.5397] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A repeated DNA sequence has been identified in the macronucleus of several Paramecium species. In P.tetraurelia the repeat was identified in the subtelomeric region of four randomly selected telomere clones, as well as downstream of the A type variable surface protein gene. The complete sequence of the A gene linked repeat consists of 15 tandem repeats of exactly 126 nucleotides that contain an open reading frame with significant similarity to the beta subunits of trimeric G proteins. The most striking consensus feature is the amino acid sequence DX omega WD where X is any amino acid and omega is I, L, or V spaced at precise 42 amino acids intervals. This sequence and spacing are found in G-protein beta subunits and other members of this protein motif family. Analysis of the five cloned telomeric restriction fragments showed the repeats can be found in either orientation with respect to the telomere. Poly(A) RNA transcripts containing this sequence have been identified in Paramecium tetraurelia. The conserved presence of this sequence in several species of Paramecium suggests an important physiological function, and the study of this repeat may reveal information about the evolution of this common protein motif.
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Affiliation(s)
- J Forney
- Department of Biochemistry, Purdue University, West Lafayette, IN 479079
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46
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Stifani S, Blaumueller CM, Redhead NJ, Hill RE, Artavanis-Tsakonas S. Human homologs of a Drosophila Enhancer of split gene product define a novel family of nuclear proteins. Nat Genet 1992; 2:119-27. [PMID: 1303260 DOI: 10.1038/ng1092-119] [Citation(s) in RCA: 240] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Notch and the m9/10 gene (groucho) of the Enhancer of split (E(spI)) complex are members of the "Notch group" of genes, which is required for a variety of cell fate choices in Drosophila. We have characterized human cDNA clones encoding a family of proteins, designated TLE, that are homologous to the E(spI) m9/10 gene product, as well as a novel Notch-related protein. The TLE genes are differentially expressed and encode nuclear proteins, consistent with the presence of sequence motifs associated with nuclear functions. The structural redundancy implied by the existence of more than one TLE and Notch-homologous gene may be a feature of the human counterparts of the developmentally important Drosophila Notch group genes.
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Affiliation(s)
- S Stifani
- Howard Hughes Medical Institute, Boyer Centre for Molecular Medicine, New Haven, Connecticut
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47
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Abstract
An amino acid sequence motif, called the WD-40 repeat, has been found as a repeat in a large variety of proteins that do not share any obvious functional properties. At present, the function of the repeated motif is not known for any of these proteins. Interestingly, recent experiments in yeast indicate that several proteins containing the WD-40 repeat are genetically associated with members of the TPR-family, a protein family that is characterized by the presence of another repeated motif of unknown function: the tetratricopeptide repeat. It is conceivable that proteins containing the WD-40 repeat interact physically with members of the TPR-family via their respective repeated motifs.
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Affiliation(s)
- L van der Voorn
- Division of Cellular Biochemistry, Netherlands Cancer Institute, Amsterdam
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48
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Duronio RJ, Gordon JI, Boguski MS. Comparative analysis of the beta transducin family with identification of several new members including PWP1, a nonessential gene of Saccharomyces cerevisiae that is divergently transcribed from NMT1. Proteins 1992; 13:41-56. [PMID: 1594577 DOI: 10.1002/prot.340130105] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
While investigating the expression of the Saccharomyces cerevisiae myristoyl-CoA:protein N-myristoyltransferase gene (NMT: E.C. 2.3.1.97) by Northern blot analysis, we observed another RNA transcript whose expression resembled that of NMT1 during meiosis and was derived from a gene located less than 1 kb immediately upstream of NMT1. This new gene, designated PWP1 (for periodic tryptophan protein), is divergently transcribed from NMT1 and encodes a 576-residue protein. Null mutants of PWP1 are viable, but their growth is severely retarded and steady-state levels of several cellular proteins (including at least two proteins that label with exogenous [3H]myristic acid) are drastically reduced. New methods for database searching and assessing the statistical significance of sequence similarities identify PWP1 as a member of the beta-transducin protein superfamily. Two other previously unrecognized beta-transducin-like proteins (S. cerevisiae MAK11 and D. discoideum AAC3) were also identified, and an unexpectedly high degree of sequence homology was found between a Chlamydomonas beta-like polypeptide and the C12.3 gene of chickens. A systematic and quantitative comparative analysis resulted in classifying all beta-transducin-like sequences into 11 nonorthologous families. Based on specific sequence attributes, however, not all beta-transducin-like sequences are expected to be functionally similar, and quantitative criteria for inferring functional analogies are discussed. Possible roles of repetitive tryptophan residues in proteins are also considered.
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Affiliation(s)
- R J Duronio
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110
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Fujita A, Misumi Y, Ikehara Y, Kobayashi H. The yeast SFL2 gene may be necessary for mating-type control. Gene X 1992; 112:85-90. [PMID: 1312982 DOI: 10.1016/0378-1119(92)90306-a] [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: 12/26/2022] Open
Abstract
We previously reported the isolation of the yeast suppressor gene for flocculation, SFL2 (TUP1). SFL2 gene disruption results in pleiotropic phenotypes; the sfl2 null mutation also causes a morphological change similar to shmoo in both the MAT alpha and MATa/alpha cells. The MAT alpha and MATa/alpha sfl2 null mutant cells incorporate chitin into the new growth zone in the same way as the alpha-factor-treated MATa cells. In order to clarify the molecular basis of this morphological change, we examined the effect of the sfl2 null mutation on the mRNA production of various genes involved in mating-type control. The transcripts of both the STE2 (an a-specific gene) and STE3 (an alpha specific gene) genes are detected in the MAT alpha and MATa/alpha cells carrying the sfl2 null mutation. In addition, mRNA of the GPA1 gene (haploid-cell-specific gene) is also detected in the MATa/alpha sfl2 cells. However, there is no significant difference in the levels of the MAT alpha 2 and MATa1 transcripts. These results suggest that the SFL2 gene product may be necessary for alpha 2 and a1-alpha 2 repression.
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Affiliation(s)
- A Fujita
- Fermentation Research Institute, Agency of Industrial Science and Technology, MITI, Ibaraki, Japan
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50
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von Weizsäcker E, Strathmann MP, Simon MI. Diversity among the beta subunits of heterotrimeric GTP-binding proteins: characterization of a novel beta-subunit cDNA. Biochem Biophys Res Commun 1992; 183:350-6. [PMID: 1543505 DOI: 10.1016/0006-291x(92)91650-f] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Heterotrimeric guanine nucleotide binding proteins transduce signals from cell surface receptors to intracellular effectors. The alpha subunit is believed to confer receptor and effector specificity on the G protein. This role is reflected in the diversity of genes that encode these subunits. The beta and gamma subunits are thought to have a more passive role in G protein function; biochemical data suggests that beta-gamma dimers are shared among the alpha subunits. However, there is growing evidence for active participation of beta-gamma dimers in some G protein mediated signaling systems. To further investigate this role, we examined the diversity of the beta subunit family in mouse. Using the polymerase chain reaction, we uncovered a new member of this family, G beta 4, which is expressed at widely varying levels in a variety of tissues. The predicted amino acid sequence of G beta 4 is 79% to 89% identical to the three previously known beta subunits. The diversity of beta gene products may be an important corollary to the functional diversity of G proteins.
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