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Takagi Y, Sindkar S, Ekonomidis D, Hall MP, Ho CK. Trypanosoma brucei encodes a bifunctional capping enzyme essential for cap 4 formation on the spliced leader RNA. J Biol Chem 2007; 282:15995-6005. [PMID: 17416901 DOI: 10.1074/jbc.m701569200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 5' end of kinetoplastid mRNA possesses a hypermethylated cap 4 structure, which is derived from standard m7GpppN (cap 0) with additional methylations at seven sites within the first four nucleosides on the spliced leader RNA. In addition to TbCe1 guanylyltransferase and TbCmt1 (guanine N-7) methyltransferase, Trypanosoma brucei encodes a second cap 0 forming enzyme. TbCgm1 (T. brucei cap guanylyltransferase-methyltransferase) is a novel bifunctional capping enzyme consisting of an amino-terminal guanylyltransferase domain and a carboxyl-terminal methyltransferase domain. Recombinant TbCgm1 transfers the GMP to spliced leader RNA (SL RNA) via a covalent enzyme-GMP intermediate, and methylates the guanine N-7 position of the GpppN-terminated RNA to form cap 0 structure. The two domains can function autonomously in vitro. TbCGM1 is essential for parasite growth. Silencing of TbCGM1 by RNA interference increased the abundance of uncapped SL RNA and lead to accumulation of hypomethylated SL RNA. In contrast, silencing of TbCE1 and TbCMT1 did not affect parasite growth or SL RNA capping. We conclude that TbCgm1 specifically cap SL RNA, and cap 0 is a prerequisite for subsequent methylation events leading to the formation of mature SL RNA.
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Affiliation(s)
- Yuko Takagi
- Department of Biological Sciences, State University of New York, Buffalo, New York 14260, USA
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2
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Kang ME, Dahmus ME. The unique C-terminal domain of RNA polymerase II and its role in transcription. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 71:41-77. [PMID: 8644491 DOI: 10.1002/9780470123171.ch2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- M E Kang
- Section of Molecular and Cellular Biology, University of California, Davis 95616, USA
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3
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Hall MP, Ho CK. Characterization of a Trypanosoma brucei RNA cap (guanine N-7) methyltransferase. RNA (NEW YORK, N.Y.) 2006; 12:488-97. [PMID: 16431985 PMCID: PMC1383586 DOI: 10.1261/rna.2250606] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The m7GpppN cap structure of eukaryotic mRNA is formed by the sequential action of RNA triphosphatase, guanylyltransferase, and (guanine N-7) methyltransferase. In trypanosomatid protozoa, the m7GpppN is further modified by seven methylation steps within the first four transcribed nucleosides to form the cap 4 structure. The RNA triphosphatase and guanylyltransferase components have been characterized in Trypanosoma brucei. Here we describe the identification and characterization of a T. brucei (guanine N-7) methyltransferase (TbCmt1). Sequence alignment of the 324-amino acid TbCmt1 with the corresponding enzymes from human (Hcm1), fungal (Abd1), and microsporidian (Ecm1) revealed the presence of conserved residues known to be essential for methyltransferase activity. Purified recombinant TbCmt1 catalyzes the transfer of a methyl group from S-adenosylmethionine to the N-7 position of the cap guanine in GpppN-terminated RNA to form the m7GpppN cap. TbCmt1 also methylates GpppG and GpppA but not GTP or dGTP. Mutational analysis of individual residues of TbCmt1 that were predicted-on the basis of the crystal structure of Ecm1--to be located at or near the active site identified six conserved residues in the putative AdoMet- or cap-binding pocket that caused significant reductions in TbCmt1 methyltransferase activity. We also report the identification of a second T. brucei RNA (guanine N-7) cap methyltransferase (named TbCgm1). The 1050-amino acid TbCgm1 consists of a C-terminal (guanine N-7) methyltransferase domain, which is homologous with TbCmt1, and an N-terminal guanylyltransferase domain, which contains signature motifs found in the nucleotidyl transferase superfamily.
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Affiliation(s)
- Megan P Hall
- Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260, USA
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4
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Abstract
Transcription start site selection in eukaryotes is mediated through combinations of the TATA, initiator (Inr), and downstream promoter elements (DPE). In Trichomonas vaginalis, a parabasalian flagellate thought to represent an ancient eukaryote lineage, the Inr appears to be solely responsible for start site selection and is recognized by the initiator binding protein 39 kDa (IBP39). IBP39 contains an N-terminal Inr binding domain (IBD) connected via a flexible linker to a C-terminal domain (C domain). Here we present crystal structures of the apoIBD and IBD-Inr complexes and the C domain. The IBD structures reveal a winged-helix motif with prokaryotic and eukaryotic features and a scaffold similar to that of ETS-family proteins. The C domain structure and biochemical studies indicate that it interacts with the T. vaginalis RNAP II large subunit C-terminal domain. These data suggest that binding of IBP39 to the Inr directly recruits RNAP II and in this way initiates transcription.
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Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR 97239, USA.
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5
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Ejchel TF, Ramirez MI, Vargas N, Azevedo EB, Elias MC, Zingales B, Schenkman S. The largest subunit of the RNA polymerase II of Trypanosoma cruzi lacks the repeats in the carboxy-terminal domain and is encoded by several genes. Parasitol Int 2004; 52:243-9. [PMID: 14550480 DOI: 10.1016/s1383-5769(03)00009-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The largest subunit of eukaryotic RNA polymerase II (RNA Pol II) of several members of Kinetoplastida order and other early diverging eukaryote contains a serine, tyrosine and proline-rich domain in the carboxyl-terminal instead of the typical heptapeptides repeats found in most eukaryotes. The lack of these repeats seems to reflect the different control of gene transcription found in these organisms. To provide further understanding in these mechanisms, we have characterized the largest subunit of RNA polymerase II (RNA Pol II LSU) in Trypanosoma cruzi. We found that it also lacks the heptapeptide repeats in the carboxy-terminal domain, but is quite similar to the same region in the Trypanosoma brucei enzyme, suggesting a conserved role for this domain. In addition, we found several genes encoding the RNA Pol II in T. cruzi, distributed in different chromosomal bands in several isolates. Two of these genes were entirely sequenced and shown to be quite similar. The presence of several gene copies of the RNA Pol II LSU, also described in African trypanosomes might reflect a gene amplification requirement that appeared early in the evolution of these organisms.
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Affiliation(s)
- Tatiana Flank Ejchel
- Departamento de Microbiologia, Imunologia e Parasitologia Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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6
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Gilinger G, Bellofatto V. Trypanosome spliced leader RNA genes contain the first identified RNA polymerase II gene promoter in these organisms. Nucleic Acids Res 2001; 29:1556-64. [PMID: 11266558 PMCID: PMC31286 DOI: 10.1093/nar/29.7.1556] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Typical general transcription factors, such as TATA binding protein and TFII B, have not yet been identified in any member of the Trypanosomatidae family of parasitic protozoa. Interestingly, mRNA coding genes do not appear to have discrete transcriptional start sites, although in most cases they require an RNA polymerase that has the biochemical properties of eukaryotic RNA polymerase II. A discrete transcription initiation site may not be necessary for mRNA synthesis since the sequences upstream of each transcribed coding region are trimmed from the nascent transcript when a short m(7)G-capped RNA is added during mRNA maturation. This short 39 nt m(7)G-capped RNA, the spliced leader (SL) sequence, is expressed as an approximately 100 nt long RNA from a set of reiterated, though independently transcribed, genes in the trypanosome genome. Punctuation of the 5' end of mRNAs by a m(7)G cap-containing spliced leader is a developing theme in the lower eukaryotic world; organisms as diverse as EUGLENA: and nematode worms, including Caenorhabditis elegans, utilize SL RNA in their mRNA maturation programs. Towards understanding the coordination of SL RNA and mRNA expression in trypanosomes, we have begun by characterizing SL RNA gene expression in the model trypanosome Leptomonas seymouri. Using a homologous in vitro transcription system, we demonstrate in this study that the SL RNA is transcribed by RNA polymerase II. During SL RNA transcription, accurate initiation is determined by an initiator element with a loose consensus of CYAC/AYR(+1). This element, as well as two additional basal promoter elements, is divergent in sequence from the basal transcription elements seen in other eukaryotic gene promoters. We show here that the in vitro transcription extract contains a binding activity that is specific for the initiator element and thus may participate in recruiting RNA polymerase II to the SL RNA gene promoter.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Binding Sites/genetics
- Binding Sites/immunology
- Blotting, Western
- DNA, Protozoan/chemistry
- DNA, Protozoan/genetics
- DNA, Protozoan/metabolism
- DNA, Recombinant/genetics
- DNA, Recombinant/metabolism
- Molecular Sequence Data
- Precipitin Tests
- Promoter Regions, Genetic/genetics
- Protein Binding
- Protein Subunits
- RNA Polymerase II/chemistry
- RNA Polymerase II/genetics
- RNA Polymerase II/metabolism
- RNA, Protozoan/genetics
- RNA, Small Nuclear/genetics
- RNA, Spliced Leader/genetics
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Transcription, Genetic
- Trypanosoma brucei brucei/genetics
- Trypanosomatina/enzymology
- Trypanosomatina/genetics
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Affiliation(s)
- G Gilinger
- Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA
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7
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Croan DG, Ellis J. The Leishmania major RNA polymerase II largest subunit lacks a carboxy-terminus heptad repeat structure and its encoding gene is linked with the calreticulin gene. Protist 2000; 151:57-68. [PMID: 10896133 DOI: 10.1078/1434-4610-00007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The gene encoding the RNA polymerase II largest subunit (RPOIILS) has been isolated and sequenced from the kinetoplastid protozoan, Leishmania (Leishmania) major. The RPOIILS gene was shown to be present as a single copy and is composed of an uninterrupted open reading frame of 4.99 kb, specifying a protein 1663 aa in length with a predicted molecular mass of approximately 185 kDa. The carboxy terminus domain (CTD) of the RPOIILS from L. (L.) major, typical of the more evolutionary primitive protozoa, lacked a heptad repeat structure which is present in higher eukaryotes and some other protozoan phyla. Comparison of the predicted aa composition of the CTD from a diverse range of eukaryotic species revealed the abundance of Ser and Pro residues as the only discernible evolutionary conservative feature. A putative ATG start codon for an additional expressed sequence was located 1.1 kb downstream of the L. (L.) major RPOIILS gene stop codon. Nucleic acid database searches revealed the identity of this gene as that encoding the calcium binding protein calreticulin (CLT). The close proximity of the RPOIILS and CLT genes in L. (L.) major raises the possibility that these genes are transcribed as part of the same polycistronic unit.
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Affiliation(s)
- D G Croan
- Molecular Parasitology Unit, Faculty of Science, University of Technology, Sydney, NSW, Australia
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8
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Nakajima K, Chang YC, Suzuki T, Jigami Y, Machida M. Molecular cloning and characterization of rpbA encoding RNA polymerase II largest subunit from a filamentous fungus, Aspergillus oryzae. Biosci Biotechnol Biochem 2000; 64:641-6. [PMID: 10803973 DOI: 10.1271/bbb.64.641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have cloned rpbA encoding the RNA polymerase II largest subunit (polIIL) from a filamentous fungus, Aspergillus oryzae. The rpbA product included eight highly conserved regions and the carboxyl-terminal domain (CTD). A. oryzae polIIL CTD with 184 amino acids was composed of 25 CTD consensus repeats, which was a similar number to those of lower eukaryotes. The amino acids in each repeat of A. oryzae polIIL, however, conformed less to the CTD consensus than those of polIILs from other lower eukaryotes.
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Affiliation(s)
- K Nakajima
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Japan
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9
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Abstract
The C-terminal domain (CTD) of the largest subunit (RPB1) of eukaryotic RNA polymerase II is essential for pol II function and has been shown to play a number of important roles in the mRNA transcription cycle. The CTD is composed of a tandemly repeated heptapeptide that is conserved in yeast, animals, plants and several protistan organisms. Some eukaryotes, however, have what appear to be degenerate or deviant CTD regions, and others have no CTD at all. The functional and evolutionary implications of this variation among RPB1 C-termini is largely unexplored. We have transformed yeast cells with a construct consisting of the yeast RPB1 gene with 25 heptads from the primitive protist Mastigamoeba invertens in place of the wild-type CTD. The Mastigamoeba heptads differ from the canonical CTD by the invariable presence of alanines in place of threonines at position 4, and in place of serines at position 7 of each heptad. Despite this double substitution, mutants are viable even under conditions of temperature and nutrient stress. These results provide new insights into the relative functional importance of several of the conserved CTD residues, and indicate that in vivo expression of evolutionary variants in yeast can provide important clues for understanding the origin, evolution and function of the pol II CTD.
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Affiliation(s)
- J W Stiller
- Department of Genetics, University of Washington, Seattle, WA 98195, USA.
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10
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Abstract
Since the cloning of the first gene from the flagellated, parasitic protist Trichomonas vaginalis in 1990, at least a partial sequence has been obtained from over 100 genes. Molecular and biochemical analyses using these genes have enhanced our understanding of metabolism, organelle biogenesis, drug susceptibility, phylogeny and basic properties of transcription in trichomonads. Here, David Liston and Patricia Johnson discuss the available data on the regulation of transcription of protein-coding genes in T. vaginalis.
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Affiliation(s)
- D R Liston
- Department of Microbiology and Immunology, Molecular Biology Institute, University of California, Los Angeles School of Medicine, Los Angeles, CA 90095-1747, USA
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11
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Quon DV, Delgadillo MG, Johnson PJ. Transcription in the early diverging eukaryote Trichomonas vaginalis: an unusual RNA polymerase II and alpha-amanitin-resistant transcription of protein-coding genes. J Mol Evol 1996; 43:253-62. [PMID: 8703091 DOI: 10.1007/bf02338833] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have examined transcription in an early diverging eukaryote by analyzing the effect of the fungus-derived toxin alpha-amanitin on the transcription of protein-coding genes of the protist Trichomonas vaginalis. In contrast to that typical in eukaryotes, the RNA polymerase that transcribes T. vaginalis protein-coding genes is relatively resistant to alpha-amanitin (50% inhibition = 250 microg alpha-amanitin/ml). We have also characterized the gene encoding the largest subunit of RNA polymerase II, the subunit that binds alpha-amanitin. This protein is 41% identical to the mouse RNA polymerase II. Sequence analysis of the 50-amino-acid region thought to bind alpha-amanitin shows that this region of the trichomonad RNA polymerase II lacks many of the conserved amino acids present in the putative binding site, in agreement with the observed insensitivity to this inhibitor. Similar to other RNA polymerase IIs analyzed from ancient eukaryotes, the T. vaginalis RNA polymerase II lacks the typical heptapeptide (Tyr-Ser-Pro-Thr-Ser-Pro-Ser) repeat carboxyl-terminal domain (CTD) that is a hallmark of higher eukaryotic RNA polymerase IIs. The trichomonad enzyme, however, does contain a short modified CTD that is rich in the amino acid residues that compose the repeat. These data suggest that T. vaginalis protein-coding genes are transcribed by a RNA polymerase II that is relatively insensitive to alpha-amanitin and that differs from typical eukaryotic RNA polymerase IIs as it lacks a heptapeptide repeated CTD.
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Affiliation(s)
- D V Quon
- Department of Microbiology and Immunology, School of Medicine, University of California, Los Angeles, 90095-1747, USA
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12
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Bakó L, Nuotio S, Dudits D, Schell J, Koncz C. RNAPII: a specific target for the cell cycle kinase complex. Results Probl Cell Differ 1994; 20:25-64. [PMID: 8036318 DOI: 10.1007/978-3-540-48037-2_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- L Bakó
- Institute of Plant Physiology, Hungarian Academy of Sciences, Szeged
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13
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Chapter 12 Transcription in archaea. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/s0167-7306(08)60261-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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14
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Barron-Casella E, Corden JL. Conservation of the mammalian RNA polymerase II largest-subunit C-terminal domain. J Mol Evol 1992; 35:405-10. [PMID: 1487824 DOI: 10.1007/bf00171818] [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: 12/27/2022]
Abstract
We have isolated and sequenced a portion of the gene encoding the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II from three mammals. These mammalian sequences include one rodent and two primate CTDs. Comparisons of the new sequences to mouse and Chinese hamster show a high degree of conservation among the mammalian CTDs. Due to synonymous codon usage, the nucleotide differences between hamster, rat, ape, and human result in no amino acid changes. The amino acid sequence for the mouse CTD appears to have one different amino acid when compared to the other four sequences. Therefore, except for the one variation in mouse, all of the known mammalian CTDs have identical amino acid sequences. This is in marked contrast to the situation among more divergent species. The present study suggests that there is a strong evolutionary pressure to maintain the primary structure of the mammalian CTD.
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Affiliation(s)
- E Barron-Casella
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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15
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Giesecke H, Barale JC, Langsley G, Cornelissen AW. The C-terminal domain of RNA polymerase II of the malaria parasite Plasmodium berghei. Biochem Biophys Res Commun 1991; 180:1350-5. [PMID: 1840489 DOI: 10.1016/s0006-291x(05)81344-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The C-terminal domain (CTD) of RNA polymerase II (RNAP) has an essential function in the regulation of transcription. The CTD of the human malaria parasite, Plasmodium falciparum, differs dramatically from that of higher eukaryotes. To determine whether this is a general feature of malarial parasites, we have analysed the CTD of the distantly related rodent malaria parasite P.berghei. The CTDs of the two parasites enzymes are very similar in amino acid composition and contain the basic structure of most eukaryotic CTDs, which is a tandem repeat of a heptapeptide (SPTSPSY). The CTD of P.berghei differs, however, in three aspects from the CTD of P.falciparum and other eukaryotes. First, both domains show a divergence from the consensus sequence at position 6 of the heptapeptide repeat. The Ser6 is always substituted, with a bias for lysine. The latter substitution might increase the binding efficiency to the DNA template. Second, the rodent and human malarial CTDs contain a 3' extension of, respectively, 66 or 67 amino acid residues. This tail-piece is unique among eukaryotes. Third, the enlargement of the CTD of the human parasite by six heptapeptide repeats is most likely generated by a recent amplification of a specific repeat unit.
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Affiliation(s)
- H Giesecke
- Max-Planck-Institut für Biologie, Molecular Parasitology Unit, Tübingen, FRG
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16
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Abstract
We have characterized the crithidial RNA polymerases (RNAPs). The RNAPs from this organism were resolved by chromatography and could be classified into RNAP I, II and III because of their differential sensitivity to class-specific RNA polymerase inhibitors, such as alpha-amanitin (ama) and tagetitoxin. The three RNAP classes were subsequently characterized in nuclear run-ons using class-specific DNA templates and the inhibitory effect of ama on RNA chain elongation. These experiments showed that Crithidia fasciculata contains the normal set of eukaryotic RNAPs. However, RNAP II was found to be relatively resistant to ama, which seems to be a general feature of kinetoplastid parasites. Tagetitoxin, a potent inhibitor of purified crithidial RNAP III, does not inhibit RNAP III in nuclear run-on experiments, suggesting that the inhibitory effect of tagetitoxin depends on the enzyme conformation, i.e. 'naked' enzyme versus that in a transcription complex. Finally, the role of RNAP III in the transcription of the mini-exon genes, which provide the 5' end of each mRNA, is discussed.
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Affiliation(s)
- J Köck
- Max-Planck-Institut für Biologie, Molecular Parasitology Unit, Tübingen, Germany
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17
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Jess W, Palm P, Evers R, Köck J, Cornelissen AW. Phylogenetic analysis of the RNA polymerases of Trypanosoma brucei, with special reference to class-specific transcription. Curr Genet 1990; 18:547-51. [PMID: 2076555 DOI: 10.1007/bf00327026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have sequenced the genes encoding to largest subunits of the three classes of DNA-dependent RNA polymerases of Trypanosoma brucei. The nucleotide and deduced amino acid sequences were compared and aligned with the corresponding sequences of other eukaryotes. Phylogenetic relationships were subsequently calculated with a distant matrix, a bootstrapped parsimony and a maximum-likelihood method. These independent calculations resulted in trees with very similar topologies. The analyses show that all the largest subunits of T. brucei are evolutionarily distant members within each of the three RNA polymerase classes. An early separation of the trypanosomal subunits from the eukaryotic lineage might form the fundamental basis for the unusual transcription process of this species. Finally, all dendrograms show a separate ramification for the largest subunit of RNA polymerase I, II and III. RNA polymerase II and/or III form a bifurcation with the archaebacterial lineage, RNA polymerase I, however, arises separately from the eubacterial beta' lineage. This suggests that the three eukaryotic RNA polymerase classes are not simply derived by two gene duplications of an ancestral gene with subsequent differentiation.
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Affiliation(s)
- W Jess
- Max-Planck-Institut für Biologie, Molecular Parasitology Unit, Tübingen, Federal Republic of Germany
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18
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Dietrich MA, Prenger JP, Guilfoyle TJ. Analysis of the genes encoding the largest subunit of RNA polymerase II in Arabidopsis and soybean. PLANT MOLECULAR BIOLOGY 1990; 15:207-23. [PMID: 2103447 DOI: 10.1007/bf00036908] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/1990] [Accepted: 04/19/1990] [Indexed: 12/16/2023]
Abstract
We have cloned and sequenced the gene encoding the largest subunit of RNA polymerase II (RPB1) from Arabidopsis thaliana and partially sequenced genes from soybean (Glycine max). We have also determined the nucleotide sequence for a number of cDNA clones which encode the carboxyl terminal domains (CTDs) of RNA polymerase II from both soybean and Arabidopsis. The Arabidopsis RPB1 gene encodes a polypeptide of approximately 205 kDa, consists of 12 exons, and encompasses more than 8 kb. Predicted amino acid sequence shows eight regions of similarity with the largest subunit of other prokaryotic and eukaryotic RNA polymerases, as well as a highly conserved CTD unique to RNA polymerase II. The CTDs in plants, like those in most other eukaryotes, consist of tandem heptapeptide repeats with the consensus amino acid sequence PTSPSYS. The portion of RPB1 which encodes the CTD in plants differs from that of RPB1 of animals and lower eukaryotes. All the plant genes examined contain 2-3 introns within the CTD encoding regions, and at least two plant genes contain an alternatively spliced intron in the 3' untranslated region. Several clustered amino acid substitutions in the CTD are conserved in the two plant species examined, but are not found in other eukaryotes. RPB1 is encoded by a multigene family in soybean, but a single gene encodes this subunit in Arabidopsis and most other eukaryotes.
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Affiliation(s)
- M A Dietrich
- Department of Plant Biology, University of Minnesota, St. Paul 55108
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19
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Igloi GL, Meinke A, Döry I, Kössel H. Nucleotide sequence of the maize chloroplast rpo B/C1/C2 operon: comparison between the derived protein primary structures from various organisms with respect to functional domains. MOLECULAR & GENERAL GENETICS : MGG 1990; 221:379-94. [PMID: 2381419 DOI: 10.1007/bf00259403] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The genes (rpo B/C1/C2) coding for the beta, beta', beta" subunits of maize (Zea mays) chloroplast RNA polymerase have been located on the plastome and their nucleotide sequences established. The operon is part of a large inversion with respect to the tobacco and spinach chloroplast genomes and is flanked by the genes trnC and rps2. Notable features of the nucleotide sequence are the loss of an intron in rpoC1 and an insertion of approximately 450 bp in rpoC2 compared to the dicotyledons tobacco, spinach and liverwort. The derived amino acid sequence of this additional monocotyledon specific sequence is characterized by acidic heptameric repeat units containing stretches of glutamic acid, tyrosines and leucines with regular spacing. Other structural motifs, such as a nucleotide binding domain in the beta subunit and a zinc finger in the beta' subunit, are compared at the amino acid level throughout the RNA polymerase subunits with the enzymes from other organisms in order to identify functionally important conserved regions.
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Affiliation(s)
- G L Igloi
- Institut für Biologie III der Universität Freiburg, Federal Republic of Germany
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20
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Shimada H, Fukuta M, Ishikawa M, Sugiura M. Rice chloroplast RNA polymerase genes: the absence of an intron in rpoC1 and the presence of an extra sequence in rpoC2. MOLECULAR & GENERAL GENETICS : MGG 1990; 221:395-402. [PMID: 2381420 DOI: 10.1007/bf00259404] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The chloroplast genome contains sequences homologous to the Escherichia coli rpoA, rpoB and rpoC genes. The chloroplast rpoC gene is divided into rpoC1 and rpoC2, of which rpoC1 contains an intron. Comparison of the rice rpo genes with those from tobacco, spinach and liverwort revealed unique features of the rice genes; the lack of an intron in rpoC1 and the presence of an extra sequence of 381 bp in rpoC2. The intron in rpoC1 is thus optional, and possible intron boundary sites in split rpoC1 genes can be estimated by comparison with rice rpoC1. The extra sequence is located in the middle of rpoC2 and has repeated structures. The amino acid sequence deduced from this sequence is extremely hydrophilic and anionic. The origin and function of this sequence are discussed.
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Affiliation(s)
- H Shimada
- Center for Gene Research, Nagoya University, Chikusa, Japan
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Molecular characterization of the Trypanosoma brucei RNA polymerase I and III largest subunit genes. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84682-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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