1
|
Levitz TS, Andree GA, Jonnalagadda R, Dawson CD, Bjork RE, Drennan CL. A rapid and sensitive assay for quantifying the activity of both aerobic and anaerobic ribonucleotide reductases acting upon any or all substrates. PLoS One 2022; 17:e0269572. [PMID: 35675376 PMCID: PMC9176816 DOI: 10.1371/journal.pone.0269572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 05/23/2022] [Indexed: 01/21/2023] Open
Abstract
Ribonucleotide reductases (RNRs) use radical-based chemistry to catalyze the conversion of all four ribonucleotides to deoxyribonucleotides. The ubiquitous nature of RNRs necessitates multiple RNR classes that differ from each other in terms of the phosphorylation state of the ribonucleotide substrates, oxygen tolerance, and the nature of both the metallocofactor employed and the reducing systems. Although these differences allow RNRs to produce deoxyribonucleotides needed for DNA biosynthesis under a wide range of environmental conditions, they also present a challenge for establishment of a universal activity assay. Additionally, many current RNR assays are limited in that they only follow the conversion of one ribonucleotide substrate at a time, but in the cell, all four ribonucleotides are actively being converted into deoxyribonucleotide products as dictated by the cellular concentrations of allosteric specificity effectors. Here, we present a liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based assay that can determine the activity of both aerobic and anaerobic RNRs on any combination of substrates using any combination of allosteric effectors. We demonstrate that this assay generates activity data similar to past published results with the canonical Escherichia coli aerobic class Ia RNR. We also show that this assay can be used for an anaerobic class III RNR that employs formate as the reductant, i.e. Streptococcus thermophilus RNR. We further show that this class III RNR is allosterically regulated by dATP and ATP. Lastly, we present activity data for the simultaneous reduction of all four ribonucleotide substrates by the E. coli class Ia RNR under various combinations of allosteric specificity effectors. This validated LC-MS/MS assay is higher throughput and more versatile than the historically established radioactive activity and coupled RNR activity assays as well as a number of the published HPLC-based assays. The presented assay will allow for the study of a wide range of RNR enzymes under a wide range of conditions, facilitating the study of previously uncharacterized RNRs.
Collapse
Affiliation(s)
- Talya S. Levitz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Gisele A. Andree
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Rohan Jonnalagadda
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Christopher D. Dawson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Rebekah E. Bjork
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Catherine L. Drennan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States of America,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, United States of America,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, United States of America,Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States of America,* E-mail:
| |
Collapse
|
2
|
Watson RA, Offenbacher AR, Barry BA. Detection of Catalytically Linked Conformational Changes in Wild-Type Class Ia Ribonucleotide Reductase Using Reaction-Induced FTIR Spectroscopy. J Phys Chem B 2021; 125:8362-8372. [PMID: 34289692 DOI: 10.1021/acs.jpcb.1c03038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The enzyme, ribonucleotide reductase (RNR), is essential for DNA synthesis in all cells. The class Ia Escherichia coli RNR consists of two dimeric subunits, α2 and β2, which form an active but unstable heterodimer of dimers, α2β2. The structure of the wild-type form of the enzyme has been challenging to study due to the instability of the catalytic complex. A long-range proton-coupled electron-transfer (PCET) pathway facilitates radical migration from the Y122 radical-diiron cofactor in the β subunit to an active site cysteine, C439, in the α subunit to initiate the RNR chemistry. The PCET reactions and active site chemistry are spectroscopically masked by a rate-limiting, conformational gate. Here, we present a reaction-induced Fourier transform infrared (RIFTIR) spectroscopic method to monitor the mechanism of the active, wild-type RNR α2β2 complex. This method is employed to obtain new information about conformational changes accompanying RNR catalysis, including the role of carboxylate interactions, deprotonation, and oxidation of active site cysteines, and a detailed description of reversible secondary structural changes. Labeling of tyrosine revealed a conformationally active tyrosine in the β subunit, assigned to Y356β, which is part of the intersubunit PCET pathway. New insights into the roles of the inhibitors, azidoUDP and dATP, and the sensitivity of RIFTIR spectroscopy to detect subtle conformational motions arising from protein allostery are also presented.
Collapse
Affiliation(s)
- Ryan Atlee Watson
- Department of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - Adam R Offenbacher
- Department of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States.,Department of Chemistry, East Carolina University, Greenville, North Carolina, United States
| | - Bridgette A Barry
- Department of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States
| |
Collapse
|
3
|
Kaushik V, Singh A, Arya A, Sindhu SC, Sindhu A, Singh A. Enhanced production of cordycepin in Ophiocordyceps sinensis using growth supplements under submerged conditions. BIOTECHNOLOGY REPORTS (AMSTERDAM, NETHERLANDS) 2020; 28:e00557. [PMID: 33294405 PMCID: PMC7691154 DOI: 10.1016/j.btre.2020.e00557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 10/24/2020] [Accepted: 11/09/2020] [Indexed: 11/23/2022]
Abstract
Cordycepin is a crucial bioactive compound produced by the fungus Cordyceps spp. Its therapeutic potential has been recognized for a wide range of biological properties such as anticancer, anti-diabetic, antidepressant, antioxidant, immunomodulation, etc. Moreover, its human random clinical trials depicted a promising anti-inflammatory activity that reduced the airway inflammation remarkably in asthmatic patients. But its overexploitation and low production of cordycepin in naturally growing biomass are insufficient to meet its existing market demand for its therapeutic use. Therefore, strategies for enhancement of cordycepin production in Cordyceps spp. are warranted. However, specifically, wild type Ophiocordyceps sinensis possesses a very low content of cordycepin and has restricted growth in natural mycelial biomass. To overcome these limitations, this study attempted to enhance cordycepin production in its mycelial biomass in vitro under submerged conditions by adding various growth supplements. The effect of these growth supplements was evaluated by reversed-phase high-performance liquid chromatography (RP-HPLC) which demonstrated that among nucleosides- hypoxanthine and adenosine; amino acids-glycine and glutamine; plant hormones- 1-naphthaleneacetic acid (NAA) and 3-indoleacetic acid (IAA); vitamin-thiamine (B1) from each group of growth supplements yielded a higher amount of cordycepin with 466.48 ± 3.88, 380.23 ± 1.78, 434.97 ± 2.32, 269.78 ± 2.92, 227.61 ± 2.34, 226.02 ± 1.69 and 185.26 ± 2.35 mg/L respectively as compared to control with 13.66 ± 0.64 mg/L. Further, at the transcriptional level, quantitative real time-polymerase chain reaction (qRT-PCR) analysis of genes associated with metabolism and cordycepin biosynthesis depicted significant upregulation of major downstream genes- NT5E, RNR, purA, and ADEK which corroborated well with RP-HPLC analysis. Taken together, the present study identified growth supplements as potential precursors to activate the cordycepin biosynthesis pathway leading to improved cordycepin production in O. sinensis.
Collapse
Key Words
- ANOVA, Analysis of Variance
- Cordycepin biosynthesis pathway
- Cordycepin production
- Growth supplements
- KH2PO4, Potassium dihydrogen phosphate
- Medicinal mushroom
- MgSO4, Magnesium sulfate
- Mycelial biomass
- RP-HPLC, Reversed-phase high-performance liquid chromatography
- SDA, Sabouraud dextrose agar
- SEM, Standard error mean
- cDNA, Complementary deoxyribonucleic acid
- dNTP, Deoxyribonucleotide triphosphate
- mRNA, Messenger ribonucleic acid
- mTOR, Mammalian target of rapamycin
- qRT-PCR, Quantitative reverse transcriptase-polymerase chain reaction
Collapse
Affiliation(s)
- Vikas Kaushik
- Department of Biotechnology, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, 131039, Sonepat, Haryana, India
| | - Amanvir Singh
- Department of Chemistry, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, 131039, Sonepat, Haryana, India
| | - Aditi Arya
- Department of Biotechnology, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, 131039, Sonepat, Haryana, India
| | - Sangeeta Chahal Sindhu
- Department of Foods and Nutrition, Chaudhary Charan Singh Haryana Agricultural University, Hisar, 125004, Haryana, India
| | - Anil Sindhu
- Department of Biotechnology, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, 131039, Sonepat, Haryana, India
| | - Ajay Singh
- Haryana Agro Industries Corporation, Research and Development Centre, Murthal, 131039, Sonepat, Haryana, India
| |
Collapse
|
4
|
Peters GJ, Leyva A, Schwartsmann G. Resistance to differentiation affects ribo- and deoxyribonucleotide pools and sensitivity to pyrimidine metabolism antagonists in HL60 cells. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2020; 39:1369-1378. [PMID: 32727257 DOI: 10.1080/15257770.2020.1782933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
HL60 myeloid leukemia cells are extensively used as a differentiation model. We investigated a variant of HL60 which is resistant to differentiation induction (HL60-R) by standard differentiation inducers such as retinoic acid and dimethylsulfoxide (DMSO). To find an explanation for this resistance, we examined nucleotide (NTP) and deoxynucleotide (dNTP) pools in HL60-R and its parent cell line, sensitive to differentiation, HL60-S. We also explored whether these differences led to a difference in sensitivity to various antimetabolites. Drug sensitivity was measured with the tetrazolium (MTT) assay, while nucleotides were measured with anion-exchange HPLC. HL60-R cells were between 2- and 5-fold resistant to the antimetabolites 5-fluorouracil, Brequinar, hydroxyurea and N-(phosphonacetyl)-L-aspartate (PALA), but more sensitive to aza-2'-deoxycytidine (DAC), cytarabine and thymidine (5- to 10-fold). The NTP pools in both HL60 variants showed a normal pattern with ATP being the highest (2530-2876 pmol/106 cells) and CTP being lowest. However, UTP pools were 2-fold higher in the HL60-S cells (p < .01), while CTP and GTP pools were 30% higher (p < .01) compared to HL60-R cells. For the dNTP pools, larger differences were observed, with dATP (50 pmol/106 cells) being highest in HL60-R cells, but dATP was 4-fold lower in HL60-S cells. In HL-60-R, the triple combination retinoic acid, DMSO and DAC increased all NTPs almost 2-fold in contrast to HL60-S. Uridine increased UTP (1.4-fold), CTP (2-fold) and dCTP (1.4.-fold) pools in both cell lines, but thymidine increased only dTTP pools (4- to 7-fold), with a depletion of dCTP. PALA decreased UTP and CTP in both cell lines, but increased ATP (only in HL60-R). Hydroxyurea decreased dNTP especially in HL60-S cells. In conclusion, the pronounced differences in NTP and dNTP pools between HL60-S and HL60-R possibly play a role in the induction of differentiation and drug sensitivity.
Collapse
Affiliation(s)
- Godefridus J Peters
- Laboratory Medical Oncology, Amsterdam UMC, Location VUMC, Amsterdam, the Netherlands.,Department of Biochemistry, Medical University of Gdansk, Gdansk, Poland
| | - Albert Leyva
- Department of Physiology and Pharmacology, Federal University of Ceara, Ceara, Brazil
| | - Gilberto Schwartsmann
- Department of Internal Medicine, Faculty of Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| |
Collapse
|
5
|
The yeast Aft1 transcription factor activates ribonucleotide reductase catalytic subunit RNR1 in response to iron deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194522. [PMID: 32147528 DOI: 10.1016/j.bbagrm.2020.194522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/25/2020] [Accepted: 03/01/2020] [Indexed: 12/18/2022]
Abstract
Eukaryotic ribonucleotide reductases are iron-dependent enzymes that catalyze the rate-limiting step in the de novo synthesis of deoxyribonucleotides. Multiple mechanisms regulate the activity of ribonucleotide reductases in response to genotoxic stresses and iron deficiency. Upon iron starvation, the Saccharomyces cerevisiae Aft1 transcription factor specifically binds to iron-responsive cis elements within the promoter of a group of genes, known as the iron regulon, activating their transcription. Members of the iron regulon participate in iron acquisition, mobilization and recycling, and trigger a genome-wide metabolic remodeling of iron-dependent pathways. Here, we describe a mechanism that optimizes the activity of yeast ribonucleotide reductase when iron is scarce. We demonstrate that Aft1 and the DNA-binding protein Ixr1 enhance the expression of the gene encoding for its catalytic subunit, RNR1, in response to iron limitation, leading to an increase in both mRNA and protein levels. By mutagenesis of the Aft1-binding sites within RNR1 promoter, we conclude that RNR1 activation by iron depletion is important for Rnr1 protein and deoxyribonucleotide synthesis. Remarkably, Aft1 also activates the expression of IXR1 upon iron scarcity through an iron-responsive element located within its promoter. These results provide a novel mechanism for the direct activation of ribonucleotide reductase function by the iron-regulated Aft1 transcription factor.
Collapse
|
6
|
Bedin M, Agarwala H, Marx J, Schünemann V, Ott S, Thapper A. Synthesis and properties of a heterobimetallic iron-manganese complex and its comparison with homobimetallic analogues. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.03.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
7
|
Rose HR, Maggiolo AO, McBride MJ, Palowitch GM, Pandelia ME, Davis KM, Yennawar NH, Boal AK. Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis. Biochemistry 2019; 58:1845-1860. [PMID: 30855138 PMCID: PMC6456427 DOI: 10.1021/acs.biochem.8b01252] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic α subunit. All RNRs initiate catalysis with a thiyl radical, generated in class I enzymes by a metallocofactor in a separate β subunit. Class Id RNRs use a simple mechanism of cofactor activation involving oxidation of a MnII2 cluster by free superoxide to yield a metal-based MnIIIMnIV oxidant. This simple cofactor assembly pathway suggests that class Id RNRs may be representative of the evolutionary precursors to more complex class Ia-c enzymes. X-ray crystal structures of two class Id α proteins from Flavobacterium johnsoniae ( Fj) and Actinobacillus ureae ( Au) reveal that this subunit is distinctly small. The enzyme completely lacks common N-terminal ATP-cone allosteric motifs that regulate overall activity, a process that normally occurs by dATP-induced formation of inhibitory quaternary structures to prevent productive β subunit association. Class Id RNR activity is insensitive to dATP in the Fj and Au enzymes evaluated here, as expected. However, the class Id α protein from Fj adopts higher-order structures, detected crystallographically and in solution. The Au enzyme does not exhibit these quaternary forms. Our study reveals structural similarity between bacterial class Id and eukaryotic class Ia α subunits in conservation of an internal auxiliary domain. Our findings with the Fj enzyme illustrate that nucleotide-independent higher-order quaternary structures can form in simple RNRs with truncated or missing allosteric motifs.
Collapse
Affiliation(s)
- Hannah R. Rose
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Ailiena O. Maggiolo
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Molly J. McBride
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Gavin M. Palowitch
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802
| | | | - Katherine M. Davis
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Neela H. Yennawar
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802
| | - Amie K. Boal
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802
| |
Collapse
|
8
|
Tang C, Tang S, Zhang S, Luo M, Jia G, Zhi H, Diao X. SiSTL1, encoding a large subunit of ribonucleotide reductase, is crucial for plant growth, chloroplast biogenesis, and cell cycle progression in Setaria italica. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:1167-1182. [PMID: 30534992 PMCID: PMC6382339 DOI: 10.1093/jxb/ery429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 11/30/2018] [Indexed: 05/15/2023]
Abstract
The activity of ribonucleotide reductase (RNR), which catalyses the transformation of four ribonucleoside diphosphates (NDPs) to their corresponding deoxyribonucleoside diphosphates (dNDPs), is the main determiner of the cellular concentration of dNTP pools and should be tightly coordinated with DNA synthesis and cell-cycle progression. Constitutively increased or decreased RNR activity interferes with DNA replication and leads to arrested cell cycle progression; however, the mechanisms underlying these disruptive effects in higher plants remain to be uncovered. In this study, we identified a RNR large subunit mutant, sistl1, in Setaria italica (foxtail millet), which exhibited growth retardation as well as striped leaf phenotype, i.e. irregularly reduced leaf vein distances and decreased chloroplast biogenesis. We determined that a Gly737 to Glu substitution occurring in the C-terminus of the SiSTL1 protein slightly affected its optimal function, leading in turn to the reduced expression of genes variously involved in the assembly and activation of the DNA pre-replicative complex, elongation of replication forks and S phase entry. Our study provides new insights into how SiSTL1 regulates plant growth, chloroplast biogenesis, and cell cycle progression in Poaceae crops.
Collapse
Affiliation(s)
- Chanjuan Tang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Sha Tang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Shuo Zhang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Mingzhao Luo
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Guanqing Jia
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hui Zhi
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
- Correspondence: or
| | - Xianmin Diao
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
- Correspondence: or
| |
Collapse
|
9
|
Rozman Grinberg I, Lundin D, Sahlin M, Crona M, Berggren G, Hofer A, Sjöberg BM. A glutaredoxin domain fused to the radical-generating subunit of ribonucleotide reductase (RNR) functions as an efficient RNR reductant. J Biol Chem 2018; 293:15889-15900. [PMID: 30166338 PMCID: PMC6187632 DOI: 10.1074/jbc.ra118.004991] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/27/2018] [Indexed: 01/08/2023] Open
Abstract
Class I ribonucleotide reductase (RNR) consists of a catalytic subunit (NrdA) and a radical-generating subunit (NrdB) that together catalyze reduction of ribonucleotides to their corresponding deoxyribonucleotides. NrdB from the firmicute Facklamia ignava is a unique fusion protein with N-terminal add-ons of a glutaredoxin (Grx) domain followed by an ATP-binding domain, the ATP cone. Grx, usually encoded separately from the RNR operon, is a known RNR reductant. We show that the fused Grx domain functions as an efficient reductant of the F. ignava class I RNR via the common dithiol mechanism and, interestingly, also via a monothiol mechanism, although less efficiently. To our knowledge, a Grx that uses both of these two reaction mechanisms has not previously been observed with a native substrate. The ATP cone is in most RNRs an N-terminal domain of the catalytic subunit. It is an allosteric on/off switch promoting ribonucleotide reduction in the presence of ATP and inhibiting RNR activity in the presence of dATP. We found that dATP bound to the ATP cone of F. ignava NrdB promotes formation of tetramers that cannot form active complexes with NrdA. The ATP cone bound two dATP molecules but only one ATP molecule. F. ignava NrdB contains the recently identified radical-generating cofactor MnIII/MnIV We show that NrdA from F. ignava can form a catalytically competent RNR with the MnIII/MnIV-containing NrdB from the flavobacterium Leeuwenhoekiella blandensis In conclusion, F. ignava NrdB is fused with a Grx functioning as an RNR reductant and an ATP cone serving as an on/off switch.
Collapse
Affiliation(s)
- Inna Rozman Grinberg
- From the Department of Biochemistry and Biophysics, Stockholm University SE-10691 Stockholm, Sweden
| | - Daniel Lundin
- From the Department of Biochemistry and Biophysics, Stockholm University SE-10691 Stockholm, Sweden
| | - Margareta Sahlin
- From the Department of Biochemistry and Biophysics, Stockholm University SE-10691 Stockholm, Sweden
| | - Mikael Crona
- From the Department of Biochemistry and Biophysics, Stockholm University SE-10691 Stockholm, Sweden
- the Swedish Orphan Biovitrum AB, SE-112 76 Stockholm, Sweden
| | - Gustav Berggren
- the Department of Chemistry, Uppsala University, SE-752 36 Uppsala, Sweden, and
| | - Anders Hofer
- the Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden
| | - Britt-Marie Sjöberg
- From the Department of Biochemistry and Biophysics, Stockholm University SE-10691 Stockholm, Sweden,
| |
Collapse
|
10
|
Jin J, Kang W, Zhong C, Qin Y, Zhou R, Liu H, Xie J, Chen L, Qin Y, Zhang S. The pharmacological properties of Ophiocordyceps xuefengensis revealed by transcriptome analysis. JOURNAL OF ETHNOPHARMACOLOGY 2018; 219:195-201. [PMID: 29481852 DOI: 10.1016/j.jep.2018.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 02/02/2018] [Accepted: 02/04/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The Yao ethnic group in Xuefeng Mountains area have used Xuefeng cordyceps, the caterpillar-fungus complex of Ophiocordyceps xuefengensis, for treating a variety of diseases for long. Just like some other cordyceps, O. xuefengensis, which is identified as the sister taxon of O. sinensis in 2013, also seems to have broad pharmacological properties, not only enhancing human immunity, anti-bacteria, anti-virus, but also anti-tumor. However, investigation of the medicinal fugal species O. xuefengensis can be found only in few literature records since its pharmacological and therapeutic use is mainly in traditional Yao communities by local healers. AIM OF THE STUDY The aim of this study is to collect samples of Xuefeng cordyceps and isolate the strain of O. xuefengensis, to determine bioactive components and evaluate the anti-tumor activity, to obtain the gene expression profile of O. xuefengensis and reveal its pharmacological properties by de novo transcriptome analysis. Accordingly, we attempt to provide information and give a comprehensive understanding of this mysterious medicinal fugal species from traditional Yao communities of China. MATERIAL AND METHODS Bioactive components were determined with HPLC-DAD-Q-TOF-MS technology; in vitro anti-tumor activity against 6 cell lines was evaluated using standard MTT assay; transcriptome analysis was done by de novo sequencing; unique genes were functionally profiled basing on Gene Ontology Database and the targeted genes were examined by blast. RESULTS Trace cordycepin, an anti-tumor agent, was detected in O. xuefengensis water extract. To some extent, the raw water extract of O. xuefengensis showed in vitro anti-tumor activity, against A549, HepG2, MCF-7, PC-3 and Raji cell lines. A total of 94,858 transcripts and 49,001 unique genes were obtained, amongst, 43.4% unique genes were matched with those of O. sinensis. Not all supposed genes related to cordycepin biosynthetic pathways were found by transcriptome analysis. CONCLUSION According to the gene expression profile, O. xuefengensis is very close to medicinal fungus O. sinensis. Raw water extract of O. xuefengensis, to a certain degree, could inhibit the growth of tumor cells, indicating that this fungus could be a new resource for the exploration of anti-tumor drug.
Collapse
Affiliation(s)
- Jian Jin
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; Hunan University of Chinese Medicine, Changsha 410208, PR China
| | - Wenli Kang
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China
| | - Can Zhong
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, PR China
| | - You Qin
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; Hunan University of Chinese Medicine, Changsha 410208, PR China
| | - Rongrong Zhou
- Changchun University of Chinese Medicine, Changchun 130117, PR China
| | - Hao Liu
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; 2011 Collaboration and Innovation Center for Digital Chinese Medicine in Hunan, Changsha 410208, PR China
| | - Jing Xie
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; 2011 Collaboration and Innovation Center for Digital Chinese Medicine in Hunan, Changsha 410208, PR China
| | - Lin Chen
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; 2011 Collaboration and Innovation Center for Digital Chinese Medicine in Hunan, Changsha 410208, PR China
| | - Yuhui Qin
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; Hunan University of Chinese Medicine, Changsha 410208, PR China.
| | - Shuihan Zhang
- Institute of Chinese Materia Medica, Hunan Academy of Chinese Medicine, Changsha 410013, PR China; 2011 Collaboration and Innovation Center for Digital Chinese Medicine in Hunan, Changsha 410208, PR China.
| |
Collapse
|
11
|
Holland DO, Johnson ME. Stoichiometric balance of protein copy numbers is measurable and functionally significant in a protein-protein interaction network for yeast endocytosis. PLoS Comput Biol 2018. [PMID: 29518071 PMCID: PMC5860782 DOI: 10.1371/journal.pcbi.1006022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Stoichiometric balance, or dosage balance, implies that proteins that are subunits of obligate complexes (e.g. the ribosome) should have copy numbers expressed to match their stoichiometry in that complex. Establishing balance (or imbalance) is an important tool for inferring subunit function and assembly bottlenecks. We show here that these correlations in protein copy numbers can extend beyond complex subunits to larger protein-protein interactions networks (PPIN) involving a range of reversible binding interactions. We develop a simple method for quantifying balance in any interface-resolved PPINs based on network structure and experimentally observed protein copy numbers. By analyzing such a network for the clathrin-mediated endocytosis (CME) system in yeast, we found that the real protein copy numbers were significantly more balanced in relation to their binding partners compared to randomly sampled sets of yeast copy numbers. The observed balance is not perfect, highlighting both under and overexpressed proteins. We evaluate the potential cost and benefits of imbalance using two criteria. First, a potential cost to imbalance is that ‘leftover’ proteins without remaining functional partners are free to misinteract. We systematically quantify how this misinteraction cost is most dangerous for strong-binding protein interactions and for network topologies observed in biological PPINs. Second, a more direct consequence of imbalance is that the formation of specific functional complexes depends on relative copy numbers. We therefore construct simple kinetic models of two sub-networks in the CME network to assess multi-protein assembly of the ARP2/3 complex and a minimal, nine-protein clathrin-coated vesicle forming module. We find that the observed, imperfectly balanced copy numbers are less effective than balanced copy numbers in producing fast and complete multi-protein assemblies. However, we speculate that strategic imbalance in the vesicle forming module allows cells to tune where endocytosis occurs, providing sensitive control over cargo uptake via clathrin-coated vesicles. Protein copy numbers are often found to be stoichiometrically balanced for subunits of multi-protein complexes. Imbalance is believed to be deleterious because it lowers complex yield (the dosage balance hypothesis) and increases the risk of misinteractions, but imbalance may also provide unexplored functional benefits. We show here that the benefits of stoichiometric balance can extend to larger networks of interacting proteins. We develop a method to quantify to what degree protein networks are balanced, and apply it to two networks. We find that the clathrin-mediated endocytosis system in yeast is statistically balanced, but not perfectly so, and explore the consequences of imbalance in the form of misinteractions and endocytic function. We also show that biological networks are more robust to misinteractions than random networks when balanced, but are more sensitive to misinteractions under imbalance. This suggests evolutionary pressure for proteins to be balanced and that any conserved imbalance should occur for functional reasons. We explore one such reason in the form of bottlenecking the endocytosis process. Our method can be generalized to other networks and used to identify out-of-balance proteins. Our results provide insight into how network design, expression level regulation, and cell fitness are intertwined.
Collapse
Affiliation(s)
- David O. Holland
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Margaret E. Johnson
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
| |
Collapse
|
12
|
Rozman Grinberg I, Lundin D, Hasan M, Crona M, Jonna VR, Loderer C, Sahlin M, Markova N, Borovok I, Berggren G, Hofer A, Logan DT, Sjöberg BM. Novel ATP-cone-driven allosteric regulation of ribonucleotide reductase via the radical-generating subunit. eLife 2018; 7:31529. [PMID: 29388911 PMCID: PMC5794259 DOI: 10.7554/elife.31529] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 12/23/2017] [Indexed: 12/27/2022] Open
Abstract
Ribonucleotide reductases (RNRs) are key enzymes in DNA metabolism, with allosteric mechanisms controlling substrate specificity and overall activity. In RNRs, the activity master-switch, the ATP-cone, has been found exclusively in the catalytic subunit. In two class I RNR subclasses whose catalytic subunit lacks the ATP-cone, we discovered ATP-cones in the radical-generating subunit. The ATP-cone in the Leeuwenhoekiella blandensis radical-generating subunit regulates activity via quaternary structure induced by binding of nucleotides. ATP induces enzymatically competent dimers, whereas dATP induces non-productive tetramers, resulting in different holoenzymes. The tetramer forms by interactions between ATP-cones, shown by a 2.45 Å crystal structure. We also present evidence for an MnIIIMnIV metal center. In summary, lack of an ATP-cone domain in the catalytic subunit was compensated by transfer of the domain to the radical-generating subunit. To our knowledge, this represents the first observation of transfer of an allosteric domain between components of the same enzyme complex. When a cell copies its DNA, it uses four different building blocks called deoxyribonucleotides (dNTPs). These consist of one of the four ‘bases’ (A, T, C and G), which pair up to link the two strands of DNA in the double helix, bound to a sugar and a phosphate group. If the cell contains too little or too much of one of these building blocks, an incorrect base may be inserted into the DNA. This results in a mutation, which in bacteria can cause death, and in animals may lead to cancer. The enzyme that fabricates and carefully controls the amount of each dNTP building block inside a cell is called ribonucleotide reductase. Once there are enough building blocks in a cell the enzyme is turned off. A part of the enzyme called the ATP-cone acts as an on/off switch to control this activity. The ribonucleotide reductase consists of a large component and a small component. Until now, studies of the ATP-cone have found it only in the large component of the enzyme. However, when looking through a public database of sequence data, Rozman Grinberg et al. noticed that ribonucleotide reductases in some bacteria have their ATP-cone joined to the small component. Does this ATP-cone also control the amounts of dNTP building blocks inside cells and, if so, how? Rozman Grinberg et al. studied one such ATP-cone in a ribonucleotide reductase from a bacterium (named Leeuwenhoekiella blandensis) found in the Mediterranean Sea. This revealed that when the amount of dNTP building blocks reaches a certain limit, the ATP-cone turns off the enzyme. Examining the three-dimensional structure of the enzyme using a technique called X-ray crystallography revealed that when turned off, the enzyme’s small components are glued together in pairs. This prevents them from working. Rozman Grinberg et al. also discovered that this enzyme contains a new type of metal center with two manganese ions suggesting that a new reaction mechanism may operate in this class of ribonucleotide reductase. These findings support a theory that biological on/off switches can evolve rapidly. In addition to its evolutionary and biomedical interest, understanding how the ATP-cone works might help to improve the enzymes used in industrial processes.
Collapse
Affiliation(s)
- Inna Rozman Grinberg
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Daniel Lundin
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Mahmudul Hasan
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.,Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | | | | | - Christoph Loderer
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Margareta Sahlin
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | | | - Ilya Borovok
- Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Tel Aviv-Yafo, Israel
| | - Gustav Berggren
- Department of Chemistry, Uppsala University, Uppsala, Sweden
| | - Anders Hofer
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Derek T Logan
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Britt-Marie Sjöberg
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| |
Collapse
|
13
|
Kramer GJ, Nodwell JR. Chromosome level assembly and secondary metabolite potential of the parasitic fungus Cordyceps militaris. BMC Genomics 2017; 18:912. [PMID: 29178836 PMCID: PMC5702197 DOI: 10.1186/s12864-017-4307-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/15/2017] [Indexed: 01/30/2023] Open
Abstract
Background Cordyceps militaris is an insect pathogenic fungus that is prized for its use in traditional medicine. This and other entomopathogenic fungi are understudied sources for the discovery of new bioactive molecules. In this study, PacBio SMRT long read sequencing technology was used to sequence the genome of C. militaris with a focus on the genetic potential for secondary metabolite production in the genome assembly of this fungus. Results This is first chromosome level assembly of a species in the Cordyceps genera. In this seven chromosome assembly of 33.6 Mba there were 9371 genes identified. Cordyceps militaris was determined to have the MAT 1-1-1 and MAT 1-1-2 mating type genes. Secondary metabolite analysis revealed the potential for at least 36 distinct metabolites from a variety of classes. Three of these gene clusters had homology with clusters producing desmethylbassianin, equisetin and emericellamide that had been studied in other fungi. Conclusion Our assembly and analysis has revealed that C. militaris has a wealth of gene clusters for secondary metabolite production distributed among seven chromosomes. The identification of these gene clusters will facilitate the future study and identification of the secondary metabolites produced by this entomopathogenic fungus. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-4307-0) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Glenna J Kramer
- Department of Biochemistry, University of Toronto, MaRS Centre, West Tower, 661 University Avenue, Toronto, ON, M5G 1M1, Canada
| | - Justin R Nodwell
- Department of Biochemistry, University of Toronto, MaRS Centre, West Tower, 661 University Avenue, Toronto, ON, M5G 1M1, Canada.
| |
Collapse
|
14
|
Alnajar S, Khadka B, Gupta RS. Ribonucleotide Reductases from Bifidobacteria Contain Multiple Conserved Indels Distinguishing Them from All Other Organisms: In Silico Analysis of the Possible Role of a 43 aa Bifidobacteria-Specific Insert in the Class III RNR Homolog. Front Microbiol 2017; 8:1409. [PMID: 28824557 PMCID: PMC5535262 DOI: 10.3389/fmicb.2017.01409] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/11/2017] [Indexed: 01/05/2023] Open
Abstract
Bifidobacteria comprises an important group/order of bacteria whose members have widespread usage in the food and health industry due to their health-promoting activity in the human gastrointestinal tract. However, little is known about the underlying molecular properties that are responsible for the probiotic effects of these bacteria. The enzyme ribonucleotide reductase (RNR) plays a key role in all organisms by reducing nucleoside di- or tri- phosphates into corresponding deoxyribose derivatives required for DNA synthesis, and RNR homologs belonging to classes I and III are present in either most or all Bifidobacteriales. Comparative analyses of these RNR homologs have identified several novel sequence features in the forms of conserved signature indels (CSIs) that are exclusively found in bifidobacterial RNRs. Specifically, in the large subunit of the aerobic class Ib RNR, three CSIs have been identified that are uniquely found in the Bifidobacteriales homologs. Similarly, the large subunit of the anaerobic class III RNR contains five CSIs that are also distinctive characteristics of bifidobacteria. Phylogenetic analyses indicate that these CSIs were introduced in a common ancestor of the Bifidobacteriales and retained by all descendants, likely due to their conferring advantageous functional roles. The identified CSIs in the bifidobacterial RNR homologs provide useful tools for further exploration of the novel functional aspects of these important enzymes that are exclusive to these bacteria. We also report here the results of homology modeling studies, which indicate that most of the bifidobacteria-specific CSIs are located within the surface loops of the RNRs, and of these, a large 43 amino acid insert in the class III RNR homolog forms an extension of the allosteric regulatory site known to be essential for protein function. Preliminary docking studies suggest that this large CSI may be playing a role in enhancing the stability of the RNR dimer complex. The possible significances of the identified CSIs, as well as the distribution of RNR homologs in the Bifidobacteriales, are discussed.
Collapse
Affiliation(s)
- Seema Alnajar
- Department of Biochemistry and Biomedical Sciences, McMaster University, HamiltonON, Canada
| | - Bijendra Khadka
- Department of Biochemistry and Biomedical Sciences, McMaster University, HamiltonON, Canada
| | - Radhey S Gupta
- Department of Biochemistry and Biomedical Sciences, McMaster University, HamiltonON, Canada
| |
Collapse
|
15
|
Alterations in cellular metabolism triggered by URA7 or GLN3 inactivation cause imbalanced dNTP pools and increased mutagenesis. Proc Natl Acad Sci U S A 2017; 114:E4442-E4451. [PMID: 28416670 DOI: 10.1073/pnas.1618714114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic DNA replication fidelity relies on the concerted action of DNA polymerase nucleotide selectivity, proofreading activity, and DNA mismatch repair (MMR). Nucleotide selectivity and proofreading are affected by the balance and concentration of deoxyribonucleotide (dNTP) pools, which are strictly regulated by ribonucleotide reductase (RNR). Mutations preventing DNA polymerase proofreading activity or MMR function cause mutator phenotypes and consequently increased cancer susceptibility. To identify genes not previously linked to high-fidelity DNA replication, we conducted a genome-wide screen in Saccharomyces cerevisiae using DNA polymerase active-site mutants as a "sensitized mutator background." Among the genes identified in our screen, three metabolism-related genes (GLN3, URA7, and SHM2) have not been previously associated to the suppression of mutations. Loss of either the transcription factor Gln3 or inactivation of the CTP synthetase Ura7 both resulted in the activation of the DNA damage response and imbalanced dNTP pools. Importantly, these dNTP imbalances are strongly mutagenic in genetic backgrounds where DNA polymerase function or MMR activity is partially compromised. Previous reports have shown that dNTP pool imbalances can be caused by mutations altering the allosteric regulation of enzymes involved in dNTP biosynthesis (e.g., RNR or dCMP deaminase). Here, we provide evidence that mutations affecting genes involved in RNR substrate production can cause dNTP imbalances, which cannot be compensated by RNR or other enzymatic activities. Moreover, Gln3 inactivation links nutrient deprivation to increased mutagenesis. Our results suggest that similar genetic interactions could drive mutator phenotypes in cancer cells.
Collapse
|
16
|
Köhler C, Koalick D, Fabricius A, Parplys AC, Borgmann K, Pospiech H, Grosse F. Cdc45 is limiting for replication initiation in humans. Cell Cycle 2017; 15:974-85. [PMID: 26919204 PMCID: PMC4889307 DOI: 10.1080/15384101.2016.1152424] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cdc45 is an essential protein that together with Mcm2-7 and GINS forms the eukaryotic replicative helicase CMG. Cdc45 seems to be rate limiting for the initial unwinding or firing of replication origins. In line with this view, Cdc45-overexpressing cells fired at least twice as many origins as control cells. However, these cells displayed an about 2-fold diminished fork elongation rate, a pronounced asymmetry of replication fork extension, and an early S phase arrest. This was accompanied by H2AX-phosphorylation and subsequent apoptosis. Unexpectedly, we did not observe increased ATR/Chk1 signaling but rather a mild ATM/Chk2 response. In addition, we detected accumulation of long stretches of single-stranded DNA, a hallmark of replication catastrophe. We conclude that increased origin firing by upregulated Cdc45 caused exhaustion of the single-strand binding protein RPA, which in consequence diminished the ATR/Chk1 response; the subsequently occurring fork breaks led to an ATM/Chk2 mediated phosphorylation of H2AX and eventually to apoptosis.
Collapse
Affiliation(s)
- Carsten Köhler
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany
| | - Dennis Koalick
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany
| | - Anja Fabricius
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany
| | - Ann Christin Parplys
- b Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Kerstin Borgmann
- b Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Helmut Pospiech
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany.,c Faculty of Biochemistry and Molecular Medicine, University of Oulu , Finland
| | - Frank Grosse
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany.,d Centre for Molecular Biomedicine, Friedrich-Schiller University , Jena , Germany
| |
Collapse
|
17
|
Kato T, Ahmad S, Park EY. Functional Analysis of Ribonucleotide Reductase from Cordyceps militaris Expressed in Escherichia coli. Appl Biochem Biotechnol 2017; 182:1307-1317. [PMID: 28074332 DOI: 10.1007/s12010-017-2400-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/03/2017] [Indexed: 01/18/2023]
Abstract
Cordyceps militaris produces cordycepin (3'-deoxyadenosine), which has various activities, including anti-oxidant, anti-tumoral, anti-viral, and anti-inflammatory. Ribonucleotide reductase (RNR) seems to be a candidate to produce cordycepin in C. militaris because RNR catalyzes the reduction of nucleotides to 2'-deoxynucleotides, whose structures are similar to that of cordycepin. However, the role of RNR has not been confirmed yet. In this study, complementary DNAs (cDNAs) of C. militaris RNR (CmRNR) large and small subunits (CmR1 and CmR2) were cloned from C. militaris NBRC9787 to investigate the function of CmRNR for its cordycepin production. C. militaris NBRC9787 began to produce cordycepin when grown in a liquid surface culture in medium composed of glucose and yeast extract for 15 days. CmR1 cDNA and CmR2 cDNA were obtained from its genomic DNA and from total RNA extracted from its mycelia after cultivation for 21 days, respectively. Recombinant CmR1 and CmR2 were expressed individually in Escherichia coli and purified. Purified recombinant CmR1 and CmR2 showed RNR activity toward adenosine diphosphate (ADP) only when two subunits were mixed but only show the reduction of ADP to 2'-deoxyADP. These results indicate that the pathway from ADP to 3'deoxyADP via CmRNR does not exist in C. militaris and cordycepin production in C. militaris may be mediated by other enzymes.
Collapse
Affiliation(s)
- Tatsuya Kato
- Laboratory of Biotechnology, Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
- Laboratory of Biotechnology, Green Chemistry Research Division, Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya Suruga-ku, Shizuoka, 422-8529, Japan
- Laboratory of Biotechnology, Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Suparmin Ahmad
- Laboratory of Biotechnology, Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan
| | - Enoch Y Park
- Laboratory of Biotechnology, Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan.
- Laboratory of Biotechnology, Green Chemistry Research Division, Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya Suruga-ku, Shizuoka, 422-8529, Japan.
- Laboratory of Biotechnology, Department of Bioscience, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan.
| |
Collapse
|
18
|
Krungkrai SR, Krungkrai J. Insights into the pyrimidine biosynthetic pathway of human malaria parasite Plasmodium falciparum as chemotherapeutic target. ASIAN PAC J TROP MED 2016; 9:525-34. [PMID: 27262062 DOI: 10.1016/j.apjtm.2016.04.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 03/16/2016] [Accepted: 04/08/2016] [Indexed: 11/25/2022] Open
Abstract
Malaria is a major cause of morbidity and mortality in humans. Artemisinins remain as the first-line treatment for Plasmodium falciparum (P. falciparum) malaria although drug resistance has already emerged and spread in Southeast Asia. Thus, to fight this disease, there is an urgent need to develop new antimalarial drugs for malaria chemotherapy. Unlike human host cells, P. falciparum cannot salvage preformed pyrimidine bases or nucleosides from the extracellular environment and relies solely on nucleotides synthesized through the de novo biosynthetic pathway. This review presents significant progress on understanding the de novo pyrimidine pathway and the functional enzymes in the human parasite P. falciparum. Current knowledge in genomics and metabolomics are described, particularly focusing on the parasite purine and pyrimidine nucleotide metabolism. These include gene annotation, characterization and molecular mechanism of the enzymes that are different from the human host pathway. Recent elucidation of the three-dimensional crystal structures and the catalytic reactions of three enzymes: dihydroorotate dehydrogenase, orotate phosphoribosyltransferase, and orotidine 5'-monophosphate decarboxylase, as well as their inhibitors are reviewed in the context of their therapeutic potential against malaria.
Collapse
Affiliation(s)
- Sudaratana R Krungkrai
- Unit of Biochemistry, Department of Medical Science, Faculty of Science, Rangsit University, Pathumthani 12000, Thailand
| | - Jerapan Krungkrai
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
| |
Collapse
|
19
|
Butterfield CN, Tao L, Chacón KN, Spiro TG, Blackburn NJ, Casey WH, Britt RD, Tebo BM. Multicopper manganese oxidase accessory proteins bind Cu and heme. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1853-1859. [PMID: 26327317 DOI: 10.1016/j.bbapap.2015.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/24/2015] [Accepted: 08/27/2015] [Indexed: 10/23/2022]
Abstract
Multicopper oxidases (MCOs) catalyze the oxidation of a diverse group of metal ions and organic substrates by successive single-electron transfers to O2 via four bound Cu ions. MnxG, which catalyzes MnO2 mineralization by oxidizing both Mn(II) and Mn(III), is unique among multicopper oxidases in that it carries out two energetically distinct electron transfers and is tightly bound to accessory proteins. There are two of these, MnxE and MnxF, both approximately 12kDa. Although their sequences are similar to those found in the genomes of several Mn-oxidizing Bacillus species, they are dissimilar to those of proteins with known function. Here, MnxE and MnxF are co-expressed independent of MnxG and are found to oligomerize into a higher order stoichiometry, likely a hexamer. They bind copper and heme, which have been characterized by electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), and UV-visible (UV-vis) spectrophotometry. Cu is found in two distinct type 2 (T2) copper centers, one of which appears to be novel; heme is bound as a low-spin species, implying coordination by two axial ligands. MnxE and MnxF do not oxidize Mn in the absence of MnxG and are the first accessory proteins to be required by an MCO. This may indicate that Cu and heme play roles in electron transfer and/or Cu trafficking.
Collapse
Affiliation(s)
- Cristina N Butterfield
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University, Portland, OR 97239, United States
| | - Lizhi Tao
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Kelly N Chacón
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University, Portland, OR 97239, United States
| | - Thomas G Spiro
- Department of Chemistry, University of Washington, Seattle, WA 98195, United States
| | - Ninian J Blackburn
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University, Portland, OR 97239, United States
| | - William H Casey
- Department of Geology, University of California, Davis, CA 95616, United States
| | - R David Britt
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Bradley M Tebo
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University, Portland, OR 97239, United States.
| |
Collapse
|
20
|
Martín Sánchez C, Pérez Martín JM, Jin JS, Dávalos A, Zhang W, de la Peña G, Martínez-Botas J, Rodríguez-Acebes S, Suárez Y, Hazen MJ, Gómez-Coronado D, Busto R, Cheng YC, Lasunción MA. Disruption of the mevalonate pathway induces dNTP depletion and DNA damage. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1240-53. [PMID: 26055626 DOI: 10.1016/j.bbalip.2015.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/23/2015] [Accepted: 06/01/2015] [Indexed: 12/21/2022]
Abstract
The mevalonate pathway is tightly linked to cell division. Mevalonate derived non-sterol isoprenoids and cholesterol are essential for cell cycle progression and mitosis completion respectively. In the present work, we studied the effects of fluoromevalonate, a competitive inhibitor of mevalonate diphosphate decarboxylase, on cell proliferation and cell cycle progression in both HL-60 and MOLT-4 cells. This enzyme catalyzes the synthesis of isopentenyl diphosphate, the first isoprenoid in the cholesterol biosynthesis pathway, consuming ATP at the same time. Inhibition of mevalonate diphosphate decarboxylase was followed by a rapid accumulation of mevalonate diphosphate and the reduction of ATP concentrations, while the cell content of cholesterol was barely affected. Strikingly, mevalonate diphosphate decarboxylase inhibition also resulted in the depletion of dNTP pools, which has never been reported before. These effects were accompanied by inhibition of cell proliferation and cell cycle arrest at S phase, together with the appearance of γ-H2AX foci and Chk1 activation. Inhibition of Chk1 in cells treated with fluoromevalonate resulted in premature entry into mitosis and massive cell death, indicating that the inhibition of mevalonate diphosphate decarboxylase triggered a DNA damage response. Notably, the supply of exogenously deoxyribonucleosides abolished γ-H2AX formation and prevented the effects of mevalonate diphosphate decarboxylase inhibition on DNA replication and cell growth. The results indicate that dNTP pool depletion caused by mevalonate diphosphate decarboxylase inhibition hampered DNA replication with subsequent DNA damage, which may have important consequences for replication stress and genomic instability.
Collapse
Affiliation(s)
- Covadonga Martín Sánchez
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRyCIS, 28034 Madrid, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Spain.
| | - José Manuel Pérez Martín
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - Jong-Sik Jin
- Department of Pharmacology, Section of Medical Oncology, Yale School of Medicine, New Haven, CT 06520, USA; Department of Oriental Medicine Resources, College of Environmental & Bioresource Sciences, Chonbuk National University, Jeonju, Jeonbuk, Republic of Korea.
| | - Alberto Dávalos
- Laboratory of Functional Foods, IMDEA-Food, 28036 Madrid, Spain.
| | - Wei Zhang
- State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macau, China.
| | - Gema de la Peña
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRyCIS, 28034 Madrid, Spain.
| | - Javier Martínez-Botas
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRyCIS, 28034 Madrid, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Spain.
| | - Sara Rodríguez-Acebes
- DNA Replication Group, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain.
| | - Yajaira Suárez
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Department of Pathology and the Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - María José Hazen
- Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - Diego Gómez-Coronado
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRyCIS, 28034 Madrid, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Spain.
| | - Rebeca Busto
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRyCIS, 28034 Madrid, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Spain.
| | - Yung-Chi Cheng
- Department of Pharmacology, Section of Medical Oncology, Yale School of Medicine, New Haven, CT 06520, USA.
| | - Miguel A Lasunción
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal, IRyCIS, 28034 Madrid, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Spain.
| |
Collapse
|
21
|
Ostrer L, Hamann BL, Khodursky A. Perturbed states of the bacterial chromosome: a thymineless death case study. Front Microbiol 2015; 6:363. [PMID: 25964781 PMCID: PMC4408854 DOI: 10.3389/fmicb.2015.00363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/10/2015] [Indexed: 11/24/2022] Open
Abstract
Spatial patterns of transcriptional activity in the living genome of Escherichia coli represent one of the more peculiar aspects of the E. coli chromosome biology. Spatial transcriptional correlations can be observed throughout the chromosome, and their formation depends on the state of replication in the cell. The condition of thymine starvation leading to thymineless death (TLD) is at the "cross-roads" of replication and transcription. According to a current view, e.g., (Cagliero et al., 2014), one of the cellular objectives is to segregate the processes of transcription and replication in time and space. An ultimate segregation would take place when one process is inhibited and another is not, as it happens during thymine starvation, which results in numerous molecular and physiological abnormalities associated with TLD. One of such abnormalities is the loss of spatial correlations in the vicinity of the origin of replication. We review the transcriptional consequences of replication inhibition by thymine starvation in a context of the state of DNA template in the starved cells and opine about a possible significance of normal physiological coupling between the processes of replication and transcription.
Collapse
Affiliation(s)
| | | | - Arkady Khodursky
- Department of Biochemistry, Molecular Biology and Biophysics, Biotechnology Institute, University of Minnesota, St. Paul, MN, USA
| |
Collapse
|
22
|
Maslowska KH, Makiela-Dzbenska K, Fijalkowska IJ, Schaaper RM. Suppression of the E. coli SOS response by dNTP pool changes. Nucleic Acids Res 2015; 43:4109-20. [PMID: 25824947 PMCID: PMC4417155 DOI: 10.1093/nar/gkv217] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/02/2015] [Indexed: 11/30/2022] Open
Abstract
The Escherichia coli SOS system is a well-established model for the cellular response to DNA damage. Control of SOS depends largely on the RecA protein. When RecA is activated by single-stranded DNA in the presence of a nucleotide triphosphate cofactor, it mediates cleavage of the LexA repressor, leading to expression of the 30+-member SOS regulon. RecA activation generally requires the introduction of DNA damage. However, certain recA mutants, like recA730, bypass this requirement and display constitutive SOS expression as well as a spontaneous (SOS) mutator effect. Presently, we investigated the possible interaction between SOS and the cellular deoxynucleoside triphosphate (dNTP) pools. We found that dNTP pool changes caused by deficiencies in the ndk or dcd genes, encoding nucleoside diphosphate kinase and dCTP deaminase, respectively, had a strongly suppressive effect on constitutive SOS expression in recA730 strains. The suppression of the recA730 mutator effect was alleviated in a lexA-deficient background. Overall, the findings suggest a model in which the dNTP alterations in the ndk and dcd strains interfere with the activation of RecA, thereby preventing LexA cleavage and SOS induction.
Collapse
Affiliation(s)
- Katarzyna H Maslowska
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106, Warsaw, Poland
| | | | - Iwona J Fijalkowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106, Warsaw, Poland
| | - Roel M Schaaper
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| |
Collapse
|
23
|
Barry BA. Reaction dynamics and proton coupled electron transfer: studies of tyrosine-based charge transfer in natural and biomimetic systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:46-54. [PMID: 25260243 DOI: 10.1016/j.bbabio.2014.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/27/2014] [Accepted: 09/10/2014] [Indexed: 11/25/2022]
Abstract
In bioenergetic reactions, electrons are transferred long distances via a hopping mechanism. In photosynthesis and DNA synthesis, the aromatic amino acid residue, tyrosine, functions as an intermediate that is transiently oxidized and reduced during long distance electron transfer. At physiological pH values, oxidation of tyrosine is associated with a deprotonation of the phenolic oxygen, giving rise to a proton coupled electron transfer (PCET) reaction. Tyrosine-based PCET reactions are important in photosystem II, which carries out the light-induced oxidation of water, and in ribonucleotide reductase, which reduces ribonucleotides to form deoxynucleotides. Photosystem II contains two redox-active tyrosines, YD (Y160 in the D2 polypeptide) and YZ (Y161 in the D1 polypeptide). YD forms a light-induced stable radical, while YZ functions as an essential charge relay, oxidizing the catalytic Mn₄CaO₅ cluster on each of four photo-oxidation reactions. In Escherichia coli class 1a RNR, the β2 subunit contains the radical initiator, Y122O•, which is reversibly reduced and oxidized in long range electron transfer with the α2 subunit. In the isolated E. coli β2 subunit, Y122O• is a stable radical, but Y122O• is activated for rapid PCET in an α2β2 substrate/effector complex. Recent results concerning the structure and function of YD, YZ, and Y122 are reviewed here. Comparison is made to recent results derived from bioengineered proteins and biomimetic compounds, in which tyrosine-based charge transfer mechanisms have been investigated. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
Collapse
Affiliation(s)
- Bridgette A Barry
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| |
Collapse
|
24
|
Offenbacher AR, Watson RA, Pagba CV, Barry BA. Redox-dependent structural coupling between the α2 and β2 subunits in E. coli ribonucleotide reductase. J Phys Chem B 2014; 118:2993-3004. [PMID: 24606240 DOI: 10.1021/jp501121d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ribonucleotide reductase (RNR) catalyzes the production of deoxyribonucleotides in all cells. In E. coli class Ia RNR, a transient α2β2 complex forms when a ribonucleotide substrate, such as CDP, binds to the α2 subunit. A tyrosyl radical (Y122O•)-diferric cofactor in β2 initiates substrate reduction in α2 via a long-distance, proton-coupled electron transfer (PCET) process. Here, we use reaction-induced FT-IR spectroscopy to describe the α2β2 structural landscapes, which are associated with dATP and hydroxyurea (HU) inhibition. Spectra were acquired after mixing E. coli α2 and β2 with a substrate, CDP, and the allosteric effector, ATP. Isotopic chimeras, (13)Cα2β2 and α2(13)Cβ2, were used to define subunit-specific structural changes. Mixing of α2 and β2 under turnover conditions yielded amide I (C═O) and II (CN/NH) bands, derived from each subunit. The addition of the inhibitor, dATP, resulted in a decreased contribution from amide I bands, attributable to β strands and disordered structures. Significantly, HU-mediated reduction of Y122O• was associated with structural changes in α2, as well as β2. To define the spectral contributions of Y122O•/Y122OH in the quaternary complex, (2)H4 labeling of β2 tyrosines and HU editing were performed. The bands of Y122O•, Y122OH, and D84, a unidentate ligand to the diferric cluster, previously identified in isolated β2, were observed in the α2β2 complex. These spectra also provide evidence for a conformational rearrangement at an additional β2 tyrosine(s), Yx, in the α2β2/CDP/ATP complex. This study illustrates the utility of reaction-induced FT-IR spectroscopy in the study of complex enzymes.
Collapse
Affiliation(s)
- Adam R Offenbacher
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | | | | | | |
Collapse
|
25
|
Monecke T, Buschmann J, Neumann P, Wahle E, Ficner R. Crystal structures of the novel cytosolic 5'-nucleotidase IIIB explain its preference for m7GMP. PLoS One 2014; 9:e90915. [PMID: 24603684 PMCID: PMC3946280 DOI: 10.1371/journal.pone.0090915] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 02/04/2014] [Indexed: 12/13/2022] Open
Abstract
5′-nucleotidases catalyze the hydrolytic dephosphorylation of nucleoside monophosphates. As catabolic enzymes they contribute significantly to the regulation of cellular nucleotide levels; misregulation of nucleotide metabolism and nucleotidase deficiencies are associated with a number of diseases. The seven human 5′-nucleotidases differ with respect to substrate specificity and cellular localization. Recently, the novel cytosolic 5′-nucleotidase III-like protein, or cN-IIIB, has been characterized in human and Drosophila. cN-IIIB exhibits a strong substrate preference for the modified nucleotide 7-methylguanosine monophosphate but the structural reason for this preference was unknown. Here, we present crystal structures of cN-IIIB from Drosophila melanogaster bound to the reaction products 7-methylguanosine or cytidine. The structural data reveal that the cytosine- and 7-methylguanine moieties of the products are stacked between two aromatic residues in a coplanar but off-centered position. 7-methylguanosine is specifically bound through π-π interactions and distinguished from unmodified guanosine by additional cation-π coulomb interactions between the aromatic side chains and the positively charged 7-methylguanine. Notably, the base is further stabilized by T-shaped edge-to-face stacking of an additional tryptophan packing perpendicularly against the purine ring and forming, together with the other aromates, an aromatic slot. The structural data in combination with site-directed mutagenesis experiments reveal the molecular basis for the broad substrate specificity of cN-IIIB but also explain the substrate preference for 7-methylguanosine monophosphate. Analyzing the substrate specificities of cN-IIIB and the main pyrimidine 5′-nucleotidase cN-IIIA by mutagenesis studies, we show that cN-IIIA dephosphorylates the purine m7GMP as well, hence redefining its substrate spectrum. Docking calculations with cN-IIIA and m7GMP as well as biochemical data reveal that Asn69 does not generally exclude the turnover of purine substrates thus correcting previous suggestions.
Collapse
Affiliation(s)
- Thomas Monecke
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Göttingen, Germany
- * E-mail:
| | - Juliane Buschmann
- Institut für Biochemie und Biotechnologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Piotr Neumann
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Elmar Wahle
- Institut für Biochemie und Biotechnologie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Göttingen, Germany
| |
Collapse
|
26
|
Xiang L, Li Y, Zhu Y, Luo H, Li C, Xu X, Sun C, Song J, Shi L, He L, Sun W, Chen S. Transcriptome analysis of the Ophiocordyceps sinensis fruiting body reveals putative genes involved in fruiting body development and cordycepin biosynthesis. Genomics 2014; 103:154-9. [PMID: 24440419 DOI: 10.1016/j.ygeno.2014.01.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 11/09/2013] [Accepted: 01/07/2014] [Indexed: 12/20/2022]
Abstract
Ophiocordyceps sinensis is a highly valuable and popular medicinal fungus used as a tonic and roborant for thousands of years in traditional Asian medicine. However, unsustainable harvesting practices have endangered this species and very little is known about its developmental programming, its biochemistry and genetics. To begin to address this, the transcriptome of the medicinal O. sinensis fruiting body was analyzed by high-throughput. In this O. sinensis 454-EST dataset, four mating type genes and 121 genes that may be involved in fruiting body development, especially in signal transduction and transcription regulation, were discovered. Moreover, a model was developed for the synthesis of the primary medicinal compound, cordycepin, and the putative biosynthetic enzymes identified. This transcriptome dataset provides a significant new resource for gene discovery in O. sinensis and dissection of its valuable biosynthetic and developmental pathways.
Collapse
Affiliation(s)
- Li Xiang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Ying Li
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Yingjie Zhu
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Hongmei Luo
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Chunfang Li
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Xiaolan Xu
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Chao Sun
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Jingyuan Song
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Linchun Shi
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Liu He
- National Engineering Laboratory for Breeding of Endangered Medicinal Materials, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100094, China
| | - Wei Sun
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Shilin Chen
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China.
| |
Collapse
|
27
|
Vejrup-Hansen R, Fleck O, Landvad K, Fahnøe U, Broendum SS, Schreurs AS, Kragelund BB, Carr AM, Holmberg C, Nielsen O. Spd2 assists Spd1 in modulation of RNR architecture but does not regulate deoxynucleotide pools. J Cell Sci 2014; 127:2460-70. [DOI: 10.1242/jcs.139816] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In yeasts, small intrinsically disordered proteins (IDPs) modulate ribonucleotide reductase (RNR) activity to ensure an optimal supply of dNTPs for DNA synthesis. The S. pombe Spd1 protein can directly inhibit the large RNR subunit (R1), import the small subunit (R2) into the nucleus and induce an architectural change in the R1-R2 holocomplex. Here, we report the characterization of Spd2, a protein with homology to Spd1. We show that Spd2 is a CRL4Cdt2 controlled IDP that functions together with Spd1 in the DNA damage response and in modulation of RNR architecture. However, Spd2 does not regulate dNTP pools and R2 nuclear import. Furthermore, deletion of spd2 only weakly suppresses the Rad3ATR checkpoint dependency of CRL4Cdt2 mutants. However, when we raised intracellular dNTP pools by inactivation of RNR feedback inhibition, deletion of spd2 could suppress the checkpoint dependency of CRL4Cdt2 mutant cells to the same extent as spd1. Collectively, these observations suggest that Spd1 on its own regulates dNTP pools, while it together with Spd2 modulates RNR architecture and sensitizes cells to DNA damage.
Collapse
|
28
|
Hypermutability and error catastrophe due to defects in ribonucleotide reductase. Proc Natl Acad Sci U S A 2013; 110:18596-601. [PMID: 24167285 DOI: 10.1073/pnas.1310849110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The enzyme ribonucleotide reductase (RNR) plays a critical role in the production of deoxynucleoside-5'-triphosphates (dNTPs), the building blocks for DNA synthesis and replication. The levels of the cellular dNTPs are tightly controlled, in large part through allosteric control of RNR. One important reason for controlling the dNTPs relates to their ability to affect the fidelity of DNA replication and, hence, the cellular mutation rate. We have previously isolated a set of mutants of Escherichia coli RNR that are characterized by altered dNTP pools and increased mutation rates (mutator mutants). Here, we show that one particular set of RNR mutants, carrying alterations at the enzyme's allosteric specificity site, is characterized by relatively modest dNTP pool deviations but exceptionally strong mutator phenotypes, when measured in a mutational forward assay (>1,000-fold increases). We provide evidence indicating that this high mutability is due to a saturation of the DNA mismatch repair system, leading to hypermutability and error catastrophe. The results indicate that, surprisingly, even modest deviations of the cellular dNTP pools, particularly when the pool deviations promote particular types of replication errors, can have dramatic consequences for mutation rates.
Collapse
|
29
|
McKethan BL, Spiro S. Cooperative and allosterically controlled nucleotide binding regulates the DNA binding activity of NrdR. Mol Microbiol 2013; 90:278-89. [PMID: 23941567 DOI: 10.1111/mmi.12364] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2013] [Indexed: 11/29/2022]
Abstract
Ribonucleotide reductases (RNRs) are required for the synthesis of deoxyribonucleoside triphosphates (dNTPs) from ribonucleotides. In Escherichia coli, regulation of RNR expression is co-ordinated with the cell cycle, and involves several regulatory proteins. One of these, NrdR, has recently been shown to regulate all three nrd operons that encode RNR isoenzymes. Repression by NrdR is believed to be stimulated by elevated dNTPs, although there is no direct evidence for this model. Here, we sought to elucidate the mechanism by which NrdR regulates nrd expression according to the abundance of (d)NTPs. We determined that ATP and dATP bind to NrdR in a negatively cooperative fashion, such that neither can fully occupy the protein. Both nucleotides also appear to act as positive heterotropic effectors, since the binding of one stimulates binding of the other. Nucleotide binding stimulates self-association of NrdR, with tri- and diphosphates stimulating oligomerization more effectively than monophosphates. As-prepared NrdR contains (deoxy)nucleoside monophosphates, diphosphates and triphosphates, and its DNA binding activity is inhibited by triphosphates and diphosphates but not by monophosphates. We propose a model in which NrdR selectively binds (deoxy)nucleoside triphosphates, which are hydrolysed to their monophosphate counterparts in order to regulate DNA binding.
Collapse
Affiliation(s)
- Brandon L McKethan
- Department of Molecular and Cell Biology, The University of Texas at Dallas, 800 W Campbell Road, Richardson, TX, 75080, USA
| | | |
Collapse
|
30
|
Tomter AB, Zoppellaro G, Andersen NH, Hersleth HP, Hammerstad M, Røhr ÅK, Sandvik GK, Strand KR, Nilsson GE, Bell CB, Barra AL, Blasco E, Le Pape L, Solomon EI, Andersson KK. Ribonucleotide reductase class I with different radical generating clusters. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.05.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
31
|
Buschmann J, Moritz B, Jeske M, Lilie H, Schierhorn A, Wahle E. Identification of Drosophila and human 7-methyl GMP-specific nucleotidases. J Biol Chem 2012; 288:2441-51. [PMID: 23223233 DOI: 10.1074/jbc.m112.426700] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Turnover of mRNA releases, in addition to the four regular nucleoside monophosphates, the methylated cap nucleotide in the form of 7-methylguanosine monophosphate (m(7)GMP) or diphosphate (m(7)GDP). The existence of pathways to eliminate the modified nucleotide seems likely, as its incorporation into nucleic acids is undesirable. Here we describe a novel 5' nucleotidase from Drosophila that cleaves m(7)GMP to 7-methylguanosine and inorganic phosphate. The enzyme, encoded by the predicted gene CG3362, also efficiently dephosphorylates CMP, although with lower apparent affinity; UMP and the purine nucleotides are poor substrates. The enzyme is inhibited by elevated concentrations of AMP and also cleaves m(7)GDP to the nucleoside and two inorganic phosphates, albeit less efficiently. CG3362 has equivalent sequence similarity to two human enzymes, cytosolic nucleotidase III (cNIII) and the previously uncharacterized cytosolic nucleotidase III-like (cNIII-like). We show that cNIII-like also displays 5' nucleotidase activity with a high affinity for m(7)GMP. CMP is a slightly better substrate but again with a higher K(m). The activity of cNIII-like is stimulated by phosphate. In contrast to cNIII-like, cNIII and human cytosolic nucleotidase II do not accept m(7)GMP as a substrate. We suggest that the m(7)G-specific nucleotidases protect cells against undesired salvage of m(7)GMP and its incorporation into nucleic acids.
Collapse
Affiliation(s)
- Juliane Buschmann
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany
| | | | | | | | | | | |
Collapse
|
32
|
Panjkovich A, Daura X. Exploiting protein flexibility to predict the location of allosteric sites. BMC Bioinformatics 2012; 13:273. [PMID: 23095452 PMCID: PMC3562710 DOI: 10.1186/1471-2105-13-273] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 10/17/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Allostery is one of the most powerful and common ways of regulation of protein activity. However, for most allosteric proteins identified to date the mechanistic details of allosteric modulation are not yet well understood. Uncovering common mechanistic patterns underlying allostery would allow not only a better academic understanding of the phenomena, but it would also streamline the design of novel therapeutic solutions. This relatively unexplored therapeutic potential and the putative advantages of allosteric drugs over classical active-site inhibitors fuel the attention allosteric-drug research is receiving at present. A first step to harness the regulatory potential and versatility of allosteric sites, in the context of drug-discovery and design, would be to detect or predict their presence and location. In this article, we describe a simple computational approach, based on the effect allosteric ligands exert on protein flexibility upon binding, to predict the existence and position of allosteric sites on a given protein structure. RESULTS By querying the literature and a recently available database of allosteric sites, we gathered 213 allosteric proteins with structural information that we further filtered into a non-redundant set of 91 proteins. We performed normal-mode analysis and observed significant changes in protein flexibility upon allosteric-ligand binding in 70% of the cases. These results agree with the current view that allosteric mechanisms are in many cases governed by changes in protein dynamics caused by ligand binding. Furthermore, we implemented an approach that achieves 65% positive predictive value in identifying allosteric sites within the set of predicted cavities of a protein (stricter parameters set, 0.22 sensitivity), by combining the current analysis on dynamics with previous results on structural conservation of allosteric sites. We also analyzed four biological examples in detail, revealing that this simple coarse-grained methodology is able to capture the effects triggered by allosteric ligands already described in the literature. CONCLUSIONS We introduce a simple computational approach to predict the presence and position of allosteric sites in a protein based on the analysis of changes in protein normal modes upon the binding of a coarse-grained ligand at predicted cavities. Its performance has been demonstrated using a newly curated non-redundant set of 91 proteins with reported allosteric properties. The software developed in this work is available upon request from the authors.
Collapse
Affiliation(s)
- Alejandro Panjkovich
- Institute of Biotechnology and Biomedicine, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
| | | |
Collapse
|
33
|
Ribonucleotide reductase activity is coupled to DNA synthesis via proliferating cell nuclear antigen. Curr Biol 2012; 22:720-6. [PMID: 22464192 DOI: 10.1016/j.cub.2012.02.070] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 02/06/2012] [Accepted: 02/29/2012] [Indexed: 11/24/2022]
Abstract
Synthesis of deoxynucleoside triphosphates (dNTPs) is required for both DNA replication and DNA repair and is catalyzed by ribonucleotide reductases (RNR), which convert ribonucleotides to their deoxy forms [1, 2]. Maintaining the correct levels of dNTPs for DNA synthesis is important for minimizing the mutation rate [3-7], and this is achieved by tight regulation of RNR [2, 8, 9]. In fission yeast, RNR is regulated in part by a small protein inhibitor, Spd1, which is degraded in S phase and after DNA damage to allow upregulation of dNTP supply [10-12]. Spd1 degradation is mediated by the activity of the CRL4(Cdt2) ubiquitin ligase complex [5, 13, 14]. This has been reported to be dependent on modulation of Cdt2 levels, which are cell cycle regulated, peaking in S phase, and which also increase after DNA damage in a checkpoint-dependent manner [7, 13]. We show here that Cdt2 level fluctuations are not sufficient to regulate Spd1 proteolysis and that the key step in this event is the interaction of Spd1 with the polymerase processivity factor proliferating cell nuclear antigen (PCNA), complexed onto DNA. This mechanism thus provides a direct link between DNA synthesis and RNR regulation.
Collapse
|
34
|
Hodzic J, Giovannetti E, Diosdado B, Calvo BD, Adema AD, Peters GJ. Regulation of deoxycytidine kinase expression and sensitivity to gemcitabine by micro-RNA 330 and promoter methylation in cancer cells. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2012; 30:1214-22. [PMID: 22132977 DOI: 10.1080/15257770.2011.629271] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Deoxycytidine kinase (dCK) is essential for phosphorylation of natural deoxynucleosides and analogs, such as gemcitabine and cytarabine, two widely used anticancer compounds. Regulation of dCK is complex, including Ser-74 phosphorylation. We hypothesized that dCK could be regulated by two additional mechanisms: micro-RNA (miRNA) and promoter methylation. Methylation-specific PCR (MSP) revealed methylation of the 3' GC box in three out of six cancer cell lines. The 3' GC box is located at the dCK promoter region. The methylation status was related to dCK mRNA expression. TargetScan and miRanda prediction algorithms revealed several possible miRNAs targeting dCK and identified miR-330 (micro-RNA 330) as the one conserved between the human, the chimpanzee, and the rhesus monkey genomes. Expression of miR-330 in various colon and lung cancer cell lines, as measured by QRT-PCR, varied five-fold between samples and correlated with in-vitro gemcitabine resistance (R = 0.82, p = 0.04). Exposure to gemcitabine also appeared to influence miR-330 levels in these cell lines. Furthermore, in our cell line panel, miR-330 expression negatively correlated with dCK mRNA expression (R = 0.74), suggesting a role of miR-330 in post-transcriptional regulation of dCK. In conclusion, the 3' GC box and miR-330 may regulate dCK expression in cancer cells.
Collapse
Affiliation(s)
- Jasmina Hodzic
- Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands
| | | | | | | | | | | |
Collapse
|
35
|
Ahluwalia D, Bienstock RJ, Schaaper RM. Novel mutator mutants of E. coli nrdAB ribonucleotide reductase: insight into allosteric regulation and control of mutation rates. DNA Repair (Amst) 2012; 11:480-7. [PMID: 22417940 DOI: 10.1016/j.dnarep.2012.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Revised: 01/30/2012] [Accepted: 02/10/2012] [Indexed: 10/28/2022]
Abstract
Ribonucleotide reductase (RNR) is the enzyme critically responsible for the production of the 5'-deoxynucleoside-triphosphates (dNTPs), the direct precursors for DNA synthesis. The dNTP levels are tightly controlled to permit high efficiency and fidelity of DNA synthesis. Much of this control occurs at the level of the RNR by feedback processes, but a detailed understanding of these mechanisms is still lacking. Using a genetic approach in the bacterium Escherichia coli, a paradigm for the class Ia RNRs, we isolated 23 novel RNR mutants displaying elevated mutation rates along with altered dNTP levels. The responsible amino-acid substitutions in RNR reside in three different regions: (i) the (d)ATP-binding activity domain, (ii) a novel region in the small subunit adjacent to the activity domain, and (iii) the dNTP-binding specificity site, several of which are associated with different dNTP pool alterations and different mutational outcomes. These mutants provide new insight into the precise mechanisms by which RNR is regulated and how dNTP pool disturbances resulting from defects in RNR can lead to increased mutation.
Collapse
Affiliation(s)
- Deepti Ahluwalia
- Laboratory of Molecular Genetics, National Institute of Environmental and Health Sciences, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | | | | |
Collapse
|
36
|
Defects in purine nucleotide metabolism lead to substantial incorporation of xanthine and hypoxanthine into DNA and RNA. Proc Natl Acad Sci U S A 2012; 109:2319-24. [PMID: 22308425 DOI: 10.1073/pnas.1118455109] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Deamination of nucleobases in DNA and RNA results in the formation of xanthine (X), hypoxanthine (I), oxanine, and uracil, all of which are miscoding and mutagenic in DNA and can interfere with RNA editing and function. Among many forms of nucleic acid damage, deamination arises from several unrelated mechanisms, including hydrolysis, nitrosative chemistry, and deaminase enzymes. Here we present a fourth mechanism contributing to the burden of nucleobase deamination: incorporation of hypoxanthine and xanthine into DNA and RNA caused by defects in purine nucleotide metabolism. Using Escherichia coli and Saccharomyces cerevisiae with defined mutations in purine metabolism in conjunction with analytical methods for quantifying deaminated nucleobases in DNA and RNA, we observed large increases (up to 600-fold) in hypoxanthine in both DNA and RNA in cells unable to convert IMP to XMP or AMP (IMP dehydrogenase, guaB; adenylosuccinate synthetase, purA, and ADE12), and unable to remove dITP/ITP and dXTP/XTP from the nucleotide pool (dITP/XTP pyrophosphohydrolase, rdgB and HAM1). Conversely, modest changes in xanthine levels were observed in RNA (but not DNA) from E. coli lacking purA and rdgB and the enzyme converting XMP to GMP (GMP synthetase, guaA). These observations suggest that disturbances in purine metabolism caused by known genetic polymorphisms could increase the burden of mutagenic deaminated nucleobases in DNA and interfere with gene expression and RNA function, a situation possibly exacerbated by the nitrosative stress of concurrent inflammation. The results also suggest a mechanistic basis for the pathophysiology of human inborn errors of purine nucleotide metabolism.
Collapse
|
37
|
Abstract
The Monod-Wyman-Changeux (MWC) model was conceived in 1965 to account for the signal transduction and cooperative properties of bacterial regulatory enzymes and hemoglobin. It was soon extended to pharmacological receptors for neurotransmitters and other macromolecular entities involved in intracellular and intercellular communications. Five decades later, the two main hypotheses of the model are reexamined on the basis of a variety of regulatory proteins with known X-ray structures: (a) Regulatory proteins possess an oligomeric structure with symmetry properties, and (b) the allosteric interactions between topographically distinct sites are mediated by a conformational transition established between a few preestablished states with conservation of symmetry and ligand-directed conformational selection. Several well-documented examples are adequately represented by the MWC model, yet a few possible exceptions are noted. New questions are raised concerning the dynamics of the allosteric transitions and more complex supramolecular ensembles.
Collapse
Affiliation(s)
- Jean-Pierre Changeux
- Collège de France & Institut Pasteur, URA CNRS 2182, Paris Cedex 15 75724, France.
| |
Collapse
|
38
|
Huang SW, Tzeng HF. Simultaneous determination of deoxycytidine diphosphate and deoxycytidine triphosphate by capillary electrophoresis with transient isotachophoretic stacking: a sensitive monitoring method for ribonucleotide reductase activity. Electrophoresis 2011; 33:536-42. [PMID: 22212996 DOI: 10.1002/elps.201100474] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Revised: 09/28/2011] [Accepted: 10/07/2011] [Indexed: 01/12/2023]
Abstract
A simple and rapid capillary electrophoretic method was developed for simultaneous determination of sub-micromolar 2'-deoxycytidine 5'-diphosphate (dCDP) and 2'-deoxycytidine 5'-triphosphate (dCTP) levels in enzyme assays without using radioactively labeled substrates. The separation was performed at 25°C using MES in the BGE as the terminating ion, the chloride ions in the sample buffer as the leading ion, and PEG 4000 in the BGE as the EOF suppressor for sample stacking by transient isotachophoresis (tITP). Several parameters affecting the separation were investigated, including the pH of the BGE, the concentration of sodium chloride in the sample buffer, and the concentrations of MES and PEG 4000 in the running buffer. Good separation with high separation efficiency was achieved within 6 min under optimal conditions. In comparison with the simple CZE method, the present tITP-CZE method enabled a 150-fold increase in the injection time without any decrease in resolution and the sensitivity was enhanced up to two orders of magnitude with the new method. The linear range of the method was 0.1-10 μM for dCDP and dCTP. The limits of detection of dCDP and dCTP were 85 and 73 nM, respectively. The proposed method was successfully applied for the activity assay of ribonucleotide reductase from Hep G2 and Sf9 cells.
Collapse
Affiliation(s)
- Shi-Wei Huang
- Department of Applied Chemistry, National Chi Nan University, Puli, Nantou County, Taiwan
| | | |
Collapse
|
39
|
Manzerova J, Krymov V, Gerfen GJ. Investigating the intermediates in the reaction of ribonucleoside triphosphate reductase from Lactobacillus leichmannii: An application of HF EPR-RFQ technology. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 213:32-45. [PMID: 21944735 DOI: 10.1016/j.jmr.2011.08.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 08/23/2011] [Indexed: 05/31/2023]
Abstract
In this investigation high-frequency electron paramagnetic resonance spectroscopy (HFEPR) in conjunction with innovative rapid freeze-quench (RFQ) technology is employed to study the exchange-coupled thiyl radical-cob(II)alamin system in ribonucleotide reductase from a prokaryote Lactobacillus leichmannii. The size of the exchange coupling (Jex) and the values of the thiyl radical g tensor are refined, while confirming the previously determined (Gerfen et al. (1996) [20]) distance between the paramagnets. Conclusions relevant to ribonucleotide reductase catalysis and the architecture of the active site are presented. A key part of this work has been the development of a unique RFQ apparatus for the preparation of millisecond quench time RFQ samples which can be packed into small (0.5 mm ID) sample tubes used for CW and pulsed HFEPR--lack of this ability has heretofore precluded such studies. The technology is compatible with a broad range of spectroscopic techniques and can be readily adopted by other laboratories.
Collapse
Affiliation(s)
- Julia Manzerova
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, United States
| | | | | |
Collapse
|
40
|
Zheng P, Xia Y, Xiao G, Xiong C, Hu X, Zhang S, Zheng H, Huang Y, Zhou Y, Wang S, Zhao GP, Liu X, St Leger RJ, Wang C. Genome sequence of the insect pathogenic fungus Cordyceps militaris, a valued traditional Chinese medicine. Genome Biol 2011; 12:R116. [PMID: 22112802 PMCID: PMC3334602 DOI: 10.1186/gb-2011-12-11-r116] [Citation(s) in RCA: 280] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 11/10/2011] [Accepted: 11/23/2011] [Indexed: 01/10/2023] Open
Abstract
Background Species in the ascomycete fungal genus Cordyceps have been proposed to be the teleomorphs of Metarhizium species. The latter have been widely used as insect biocontrol agents. Cordyceps species are highly prized for use in traditional Chinese medicines, but the genes responsible for biosynthesis of bioactive components, insect pathogenicity and the control of sexuality and fruiting have not been determined. Results Here, we report the genome sequence of the type species Cordyceps militaris. Phylogenomic analysis suggests that different species in the Cordyceps/Metarhizium genera have evolved into insect pathogens independently of each other, and that their similar large secretomes and gene family expansions are due to convergent evolution. However, relative to other fungi, including Metarhizium spp., many protein families are reduced in C. militaris, which suggests a more restricted ecology. Consistent with its long track record of safe usage as a medicine, the Cordyceps genome does not contain genes for known human mycotoxins. We establish that C. militaris is sexually heterothallic but, very unusually, fruiting can occur without an opposite mating-type partner. Transcriptional profiling indicates that fruiting involves induction of the Zn2Cys6-type transcription factors and MAPK pathway; unlike other fungi, however, the PKA pathway is not activated. Conclusions The data offer a better understanding of Cordyceps biology and will facilitate the exploitation of medicinal compounds produced by the fungus.
Collapse
Affiliation(s)
- Peng Zheng
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Changeux JP, Edelstein S. Conformational selection or induced fit? 50 years of debate resolved. F1000 BIOLOGY REPORTS 2011; 3:19. [PMID: 21941598 PMCID: PMC3169905 DOI: 10.3410/b3-19] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Exactly 50 years ago, biochemists raised the question of the mechanism of the conformational change that mediates “allosteric” interactions between regulatory sites and biologically active sites in regulatory/receptor proteins. Do the different conformations involved already exist spontaneously in the absence of the regulatory ligands (Monod-Wyman-Changeux), such that the complementary protein conformation would be selected to mediate signal transduction, or do particular ligands induce the receptor to adopt the conformation best suited to them (Koshland-Nemethy-Filmer—induced fit)? This is not just a central question for biophysics, it also has enormous importance for drug design. Recent advances in techniques have allowed detailed experimental and theoretical comparisons with the formal models of both scenarios. Also, it has been shown that mutated receptors can adopt constitutively active confirmations in the absence of ligand. There have also been demonstrations that the atomic resolution structures of the same protein are essentially the same whether ligand is bound or not. These and other advances in past decades have produced a situation where the vast majority of the data using different categories of regulatory proteins (including regulatory enzymes, ligand-gated ion channels, G protein-coupled receptors, and nuclear receptors) support the conformational selection scheme of signal transduction.
Collapse
Affiliation(s)
- Jean-Pierre Changeux
- Collège de France and Institut PasteurCNRS URA 2182, 25 rue du Dr Roux, 75015 ParisFrance
| | - Stuart Edelstein
- European Bioinformatics Institute and University of GenevaWellcome Trust Genome Campus, Hinxton, CB10 1SDUK
| |
Collapse
|
42
|
Abstract
Dr. Arne Holmgren (Ph.D., 1968) is recognized here as a redox pioneer, because he has published at least one article on redox biology that has been cited over 1000 times and has published at least 10 articles, each cited over 100 times. He is widely known for his seminal discoveries and in-depth studies of thioredoxins, thioredoxin reductases, and glutaredoxins. Dr. Holmgren, active throughout his career at Karolinska Institutet, Sweden, has led the field of research about these classes of proteins for more than 45 years, continuously building upon his sequence determination of Escherichia coli thioredoxin in the late 1960s and discovery of the thioredoxin fold in the 1970s. He discovered and named glutaredoxin and he determined the structure and function of several members of these glutathione-dependent disulfide oxidoreductases. He still continues to broaden the frontiers of knowledge of thioredoxin and glutaredoxin systems. The thioredoxin fold is today recognized as one of the most common protein folds and the intriguing complexity of redox systems, redox signaling, and redox control of cellular function is constantly increasing. The legacy of Dr. Holmgren's research is therefore highly relevant and important also in the context of present science. In a tribute to his work, questions need to be addressed toward the physiological importance of redox signaling and the impact of glutaredoxin and thioredoxin systems on health and disease. Dr. Holmgren helped lay the foundation for the redox biology field and opened new vistas in the process. He is truly a redox pioneer.
Collapse
Affiliation(s)
- Elias S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
| |
Collapse
|
43
|
|
44
|
Peracchi A, Mozzarelli A. Exploring and exploiting allostery: Models, evolution, and drug targeting. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:922-33. [PMID: 21035570 DOI: 10.1016/j.bbapap.2010.10.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 10/19/2010] [Accepted: 10/20/2010] [Indexed: 12/11/2022]
Abstract
The concept of allostery was elaborated almost 50years ago by Monod and coworkers to provide a framework for interpreting experimental studies on the regulation of protein function. In essence, binding of a ligand at an allosteric site affects the function at a distant site exploiting protein flexibility and reshaping protein energy landscape. Both monomeric and oligomeric proteins can be allosteric. In the past decades, the behavior of allosteric systems has been analyzed in many investigations while general theoretical models and variations thereof have been steadily proposed to interpret the experimental data. Allostery has been established as a fundamental mechanism of regulation in all organisms, governing a variety of processes that range from metabolic control to receptor function and from ligand transport to cell motility. A number of studies have shed light on how evolutionary pressures have favored and molded the development of allosteric features in specific macromolecular systems. The widespread occurrence of allostery has been recently exploited for the development and design of allosteric drugs that bind to either physiological or non-physiological allosteric sites leading to gain of function or loss of function. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
Collapse
Affiliation(s)
- Alessio Peracchi
- Department of Biochemistry and Molecular Biology, University of Parma, Parma, Italy.
| | | |
Collapse
|
45
|
Affiliation(s)
- Britt-Marie Sjöberg
- Department of Molecular Biology and Functional Genomics, Stockholm University, SE-10691 Stockholm, Sweden.
| |
Collapse
|