scholarly journals The U28 ORF of human herpesvirus-7 does not encode a functional ribonucleotide reductase R1 subunit

1999 ◽  
Vol 80 (10) ◽  
pp. 2713-2718 ◽  
Author(s):  
Yunming Sun ◽  
Joe Conner
Keyword(s):  
Ribonucleotide Reductase ◽  
De Novo ◽  
Human Herpesvirus ◽  
Cloning And Expression ◽  
Subunit Interaction ◽  
Viral Dna ◽  
Sequence Comparisons ◽  
E Coli ◽  
Ribonucleotide Reductases ◽  
Functional Equivalent

Herpesvirus ribonucleotide reductases, essential for the de novo synthesis of viral DNA, are composed of two non-identical subunits, termed R1 and R2. The U28 ORF from human herpesvirus-7 has been classified, by sequence comparisons, as a homologue of the R1 subunit from ribonucleotide reductase but no R2 ORF is present. Detailed analysis of the U28 amino acid sequence indicated that a number of essential R1 catalytic residues are absent. Cloning and expression of the U28 protein in E. coli and its subsequent characterization in subunit interaction and enzyme activity assays confirmed that it is not a functional equivalent of a herpesvirus R1. In the absence of the R2 gene, we propose that the R1 ORF has evolved a distinct, as yet unidentified, function not only in human herpesvirus-7 but also in other human betaherpesviruses.

scholarly journals Direct interfacial Y731 oxidation in α2 by a photoβ2 subunit of E. coli class Ia ribonucleotide reductase

2015 ◽  
Vol 6 (8) ◽  
pp. 4519-4524 ◽  
Author(s):  
David Y. Song ◽  
Arturo A. Pizano ◽  
Patrick G. Holder ◽  
JoAnne Stubbe ◽  
Daniel G. Nocera
Keyword(s):  
Ribonucleotide Reductase ◽  
De Novo ◽  
Building Blocks ◽  
Biological Processes ◽  
E Coli ◽  
Proton Coupled Electron Transfer ◽  
Ribonucleotide Reductases ◽  
Wide Range ◽  
Dna Replication And Repair ◽  
Fundamental Mechanism

Proton-coupled electron transfer (PCET) is a fundamental mechanism important in a wide range of biological processes including the universal reaction catalysed by ribonucleotide reductases (RNRs) in making de novo, the building blocks required for DNA replication and repair.

Specific inhibition of ribonucleotide reductases by peptides corresponding to the C-terminal of their second subunit

1991 ◽  
Vol 69 (1) ◽  
pp. 79-83 ◽  
Author(s):  
Gregory Cosentino ◽  
Pierre Lavallée ◽  
Sumanas Rakhit ◽  
Raymond Plante ◽  
Yvon Gaudette ◽  
...  
Keyword(s):  
Ribonucleotide Reductase ◽  
Synthetic Peptide ◽  
Herpes Virus ◽  
Small Subunit ◽  
Terminal Sequence ◽  
E Coli ◽  
Ribonucleotide Reductases ◽  
Human Enzyme ◽  
Bacterial Enzyme ◽  
Herpès Virus

Previous studies have shown that herpes virus ribonucleotide reductase can be inhibited by a synthetic nonapeptide whose sequence is identical to the C-terminal of the small subunit of the enzyme. This peptide is able to interfere with normal subunit association that takes place through the C-terminal of the small subunit. In this report, we illustrate that inhibition of ribonucleotide reductases by peptides corresponding to the C-terminal of subunit R2 is also observed for the enzyme isolated from Escherichia coli, hamster, and human cells. The nonapeptide corresponding to the bacterial C-terminal sequence was found to inhibit E. coli enzyme with an IC50 of 400 μM, while this peptide had no effect on mammalian ribonucleotide reductase. A corresponding synthetic peptide derived from the C-terminal of the small subunit of the human enzyme inhibited both human and hamster ribonucleotide reductases with IC50 values of 160 and 120 μM, respectively. However, this peptide had no inhibitory activity against the bacterial enzyme. Equivalent peptides derived from herpes virus ribonucleotide reductase had no effect on either the bacterial or mammalian enzymes. Thus, subunit association at the C-terminal of the small subunit appears to be a common feature of ribonucleotide reductases. In addition, the inhibitory phenomenon observed with peptides corresponding to the C-terminal appears not only to be universal, but also specific to the primary sequence of the enzyme.Key words: ribonucleotide reductase, inhibition, human, bacteria.

scholarly journals Open Reading Frame 33 of a Gammaherpesvirus Encodes a Tegument Protein Essential for Virion Morphogenesis and Egress

2009 ◽  
Vol 83 (20) ◽  
pp. 10582-10595 ◽  
Author(s):  
Haitao Guo ◽  
Lili Wang ◽  
Li Peng ◽  
Z. Hong Zhou ◽  
Hongyu Deng
Keyword(s):  
De Novo ◽  
Human Herpesvirus ◽  
Lytic Replication ◽  
Open Reading Frame ◽  
Tegument Protein ◽  
Late Gene ◽  
Viral Dna ◽  
Reading Frame ◽  
Murine Gammaherpesvirus ◽  
Virion Morphogenesis

ABSTRACT Tegument is a unique structure of herpesvirus, which surrounds the capsid and interacts with the envelope. Morphogenesis of gammaherpesvirus is poorly understood due to lack of efficient lytic replication for Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8, which are etiologically associated with several types of human malignancies. Murine gammaherpesvirus 68 (MHV-68) is genetically related to the human gammaherpesviruses and presents an excellent model for studying de novo lytic replication of gammaherpesviruses. MHV-68 open reading frame 33 (ORF33) is conserved among Alpha-, Beta-, and Gammaherpesvirinae subfamilies. However, the specific role of ORF33 in gammaherpesvirus replication has not yet been characterized. We describe here that ORF33 is a true late gene and encodes a tegument protein. By constructing an ORF33-null MHV-68 mutant, we demonstrated that ORF33 is not required for viral DNA replication, early and late gene expression, viral DNA packaging or capsid assembly but is required for virion morphogenesis and egress. Although the ORF33-null virus was deficient in release of infectious virions, partially tegumented capsids produced by the ORF33-null mutant accumulated in the cytoplasm, containing conserved capsid proteins, ORF52 tegument protein, but virtually no ORF45 tegument protein and the 65-kDa glycoprotein B. Finally, we found that the defect of ORF33-null MHV-68 could be rescued by providing ORF33 in trans or in an ORF33-null revertant virus. Taken together, our results indicate that ORF33 is a tegument protein required for viral lytic replication and functions in virion morphogenesis and egress.

scholarly journals Coenzyme B12 Controls Transcription of the Streptomyces Class Ia Ribonucleotide Reductase nrdABS Operon via a Riboswitch Mechanism

2006 ◽  
Vol 188 (7) ◽  
pp. 2512-2520 ◽  
Author(s):  
Ilya Borovok ◽  
Batia Gorovitz ◽  
Rachel Schreiber ◽  
Yair Aharonowitz ◽  
Gerald Cohen
Keyword(s):  
Ribonucleotide Reductase ◽  
Untranslated Region ◽  
De Novo ◽  
Streptomyces Coelicolor ◽  
Class Ii ◽  
Coenzyme B12 ◽  
Gene Encoding ◽  
Inhibition Of Growth ◽  
Ribonucleotide Reductases ◽  
Genes Encoding

ABSTRACT Ribonucleotide reductases (RNRs) catalyze the conversion of ribonucleotides to deoxyribonucleotides and are essential for de novo DNA synthesis and repair. Streptomycetes contain genes coding for two RNRs. The class Ia RNR is oxygen dependent, and the class II RNR is oxygen independent and requires coenzyme B12. Either RNR is sufficient for vegetative growth. We show here that the Streptomyces coelicolor M145 nrdABS genes encoding the class Ia RNR are regulated by coenzyme B12. The 5′-untranslated region of nrdABS contains a 123-nucleotide B12 riboswitch. Similar B12 riboswitches are present in the corresponding regions of eight other S. coelicolor genes. The effect of B12 on growth and nrdABS transcription was examined in a mutant in which the nrdJ gene, encoding the class II RNR, was deleted. B12 concentrations of just 1 μg/liter completely inhibited growth of the NrdJ mutant strain. Likewise, B12 significantly reduced nrdABS transcription. To further explore the mechanism of B12 repression, we isolated in the nrdJ deletion strain mutants that are insensitive to B12 inhibition of growth. Two classes of mutations were found to map to the B12 riboswitch. Both conferred resistance to B12 inhibition of nrdABS transcription and are likely to affect B12 binding. These results establish that B12 regulates overall RNR expression in reciprocal ways, by riboswitch regulation of the class Ia RNR nrdABS genes and by serving as a cofactor for the class II RNR.

scholarly journals Structure of a trapped radical transfer pathway within a ribonucleotide reductase holocomplex

Science ◽  
2020 ◽  
Vol 368 (6489) ◽  
pp. 424-427 ◽  
Author(s):  
Gyunghoon Kang ◽  
Alexander T. Taguchi ◽  
JoAnne Stubbe ◽  
Catherine L. Drennan
Keyword(s):  
Ribonucleotide Reductase ◽  
Active Site ◽  
De Novo ◽  
Reduction Reaction ◽  
Wild Type ◽  
Cryo Electron Microscopy ◽  
Ribonucleotide Reductases ◽  
Dna Biosynthesis ◽  
Radical Transfer ◽  
Resolution Structure

Ribonucleotide reductases (RNRs) are a diverse family of enzymes that are alone capable of generating 2′-deoxynucleotides de novo and are thus critical in DNA biosynthesis and repair. The nucleotide reduction reaction in all RNRs requires the generation of a transient active site thiyl radical, and in class I RNRs, this process involves a long-range radical transfer between two subunits, α and β. Because of the transient subunit association, an atomic resolution structure of an active α2β2 RNR complex has been elusive. We used a doubly substituted β2, E52Q/(2,3,5)-trifluorotyrosine122-β2, to trap wild-type α2 in a long-lived α2β2 complex. We report the structure of this complex by means of cryo–electron microscopy to 3.6-angstrom resolution, allowing for structural visualization of a 32-angstrom-long radical transfer pathway that affords RNR activity.

scholarly journals Ever-increasing viral diversity associated with the red imported fire ant Solenopsis invicta (Formicidae: Hymenoptera)

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
César Augusto Diniz Xavier ◽  
Margaret Louise Allen ◽  
Anna Elizabeth Whitfield
Keyword(s):  
Solenopsis Invicta ◽  
De Novo ◽  
Rna Virus ◽  
Housekeeping Genes ◽  
Virus Genome ◽  
Single Strand ◽  
Viral Diversity ◽  
Red Imported Fire Ant ◽  
Sequence Comparisons ◽  
Data Set

Abstract Background Advances in sequencing and analysis tools have facilitated discovery of many new viruses from invertebrates, including ants. Solenopsis invicta is an invasive ant that has quickly spread worldwide causing significant ecological and economic impacts. Its virome has begun to be characterized pertaining to potential use of viruses as natural enemies. Although the S. invicta virome is the best characterized among ants, most studies have been performed in its native range, with less information from invaded areas. Methods Using a metatranscriptome approach, we further identified and molecularly characterized virus sequences associated with S. invicta, in two introduced areas, U.S and Taiwan. The data set used here was obtained from different stages (larvae, pupa, and adults) of S. invicta life cycle. Publicly available RNA sequences from GenBank’s Sequence Read Archive were downloaded and de novo assembled using CLC Genomics Workbench 20.0.1. Contigs were compared against the non-redundant protein sequences and those showing similarity to viral sequences were further analyzed. Results We characterized five putative new viruses associated with S. invicta transcriptomes. Sequence comparisons revealed extensive divergence across ORFs and genomic regions with most of them sharing less than 40% amino acid identity with those closest homologous sequences previously characterized. The first negative-sense single-stranded RNA virus genomic sequences included in the orders Bunyavirales and Mononegavirales are reported. In addition, two positive single-strand virus genome sequences and one single strand DNA virus genome sequence were also identified. While the presence of a putative tenuivirus associated with S. invicta was previously suggested to be a contamination, here we characterized and present strong evidence that Solenopsis invicta virus 14 (SINV-14) is a tenui-like virus that has a long-term association with the ant. Furthermore, based on virus sequence abundance compared to housekeeping genes, phylogenetic relationships, and completeness of viral coding sequences, our results suggest that four of five virus sequences reported, those being SINV-14, SINV-15, SINV-16 and SINV-17, may be associated to viruses actively replicating in the ant S. invicta. Conclusions The present study expands our knowledge about viral diversity associated with S. invicta in introduced areas with potential to be used as biological control agents, which will require further biological characterization.

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