1
|
Shrestha A, Hwang SY, Kunwar S, Man Kadayat T, Park S, Liu Y, Jo H, Sheen N, Seo M, Lee ES, Kwon Y. Di-indenopyridines as topoisomerase II-selective anticancer agents: Design, synthesis, and structure-activity relationships. Bioorg Med Chem 2023; 91:117403. [PMID: 37418826 DOI: 10.1016/j.bmc.2023.117403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/29/2023] [Accepted: 07/02/2023] [Indexed: 07/09/2023]
Abstract
Topoisomerases are key molecular enzymes responsible for altering DNA topology, thus they have long been considered as attractive targets for novel chemotherapeutic agents. Topoisomerase type II (Topo II) catalytic inhibitors embrace a fresh perspective meant to get beyond drawbacks caused by topo II poisons, such as cardiotoxicity and secondary malignancies. Based on previously reported 5H-indeno[1,2-b]pyridines, here we presented new twenty-three hybrid di-indenopyridines along with their topo I/IIα inhibitory and antiproliferative activity. Most of the prepared 11-phenyl-diindenopyridines showed negligible topo I inhibitory activity, showing selectivity over topo II. Among the series, we finally selected compound 17, which displayed 100 % topo IIα inhibition at 20 μM concentration and comparable antiproliferative activity against the tested cell lines. Through competitive EtBr displacement assay, cleavable complex assay, and comet assay, compound 17 was finally determined as a non-intercalative catalytic topo IIα inhibitor. The findings in this study highlight the significance of phenolic, halophenyl, thienyl, and furyl groups at the 4-position of the indane ring in the design and synthesis of di-indenopyridines as potent catalytic topo IIα inhibitors with remarkable anticancer effects.
Collapse
Affiliation(s)
- Aarajana Shrestha
- College of Pharmacy, Yeungnam University, Gyeongsan 38541, Republic of Korea; Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, KY 40508, USA
| | - Soo-Yeon Hwang
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Surendra Kunwar
- College of Pharmacy, Yeungnam University, Gyeongsan 38541, Republic of Korea
| | - Tara Man Kadayat
- College of Pharmacy, Yeungnam University, Gyeongsan 38541, Republic of Korea; Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, KY 40508, USA
| | - Seojeong Park
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Yi Liu
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Hyunji Jo
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Naeun Sheen
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Minjung Seo
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea
| | - Eung-Seok Lee
- College of Pharmacy, Yeungnam University, Gyeongsan 38541, Republic of Korea.
| | - Youngjoo Kwon
- College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750, Republic of Korea.
| |
Collapse
|
2
|
Cao N, Tan K, Zuo X, Annamalai T, Tse-Dinh YC. Mechanistic insights from structure of Mycobacterium smegmatis topoisomerase I with ssDNA bound to both N- and C-terminal domains. Nucleic Acids Res 2020; 48:4448-4462. [PMID: 32232337 PMCID: PMC7192597 DOI: 10.1093/nar/gkaa201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 02/20/2020] [Accepted: 03/18/2020] [Indexed: 12/17/2022] Open
Abstract
Type IA topoisomerases interact with G-strand and T-strand ssDNA to regulate DNA topology. However, simultaneous binding of two ssDNA segments to a type IA topoisomerase has not been observed previously. We report here the crystal structure of a type IA topoisomerase with ssDNA segments bound in opposite polarity to the N- and C-terminal domains. Titration of small ssDNA oligonucleotides to Mycobacterium smegmatis topoisomerase I with progressive C-terminal deletions showed that the C-terminal region has higher affinity for ssDNA than the N-terminal active site. This allows the C-terminal domains to capture one strand of underwound negatively supercoiled DNA substrate first and position the N-terminal domains to bind and cleave the opposite strand in the relaxation reaction. Efficiency of negative supercoiling relaxation increases with the number of domains that bind ssDNA primarily with conserved aromatic residues and possibly with assistance from polar/basic residues. A comparison of bacterial topoisomerase I structures showed that a conserved transesterification unit (N-terminal toroid structure) for cutting and rejoining of a ssDNA strand can be combined with two different types of C-terminal ssDNA binding domains to form diverse bacterial topoisomerase I enzymes that are highly efficient in their physiological role of preventing excess negative supercoiling in the genome.
Collapse
Affiliation(s)
- Nan Cao
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Kemin Tan
- Structural Biology Center, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Xiaobing Zuo
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Thirunavukkarasu Annamalai
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| | - Yuk-Ching Tse-Dinh
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
- Biomolecular Sciences Institute, Florida International University, 11200 SW 8 St, Miami, FL 33199, USA
| |
Collapse
|
3
|
Abstract
The double-helical structure of genomic DNA is both elegant and functional in that it serves both to protect vulnerable DNA bases and to facilitate DNA replication and compaction. However, these design advantages come at the cost of having to evolve and maintain a cellular machinery that can manipulate a long polymeric molecule that readily becomes topologically entangled whenever it has to be opened for translation, replication, or repair. If such a machinery fails to eliminate detrimental topological entanglements, utilization of the information stored in the DNA double helix is compromised. As a consequence, the use of B-form DNA as the carrier of genetic information must have co-evolved with a means to manipulate its complex topology. This duty is performed by DNA topoisomerases, which therefore are, unsurprisingly, ubiquitous in all kingdoms of life. In this review, we focus on how DNA topoisomerases catalyze their impressive range of DNA-conjuring tricks, with a particular emphasis on DNA topoisomerase III (TOP3). Once thought to be the most unremarkable of topoisomerases, the many lives of these type IA topoisomerases are now being progressively revealed. This research interest is driven by a realization that their substrate versatility and their ability to engage in intimate collaborations with translocases and other DNA-processing enzymes are far more extensive and impressive than was thought hitherto. This, coupled with the recent associations of TOP3s with developmental and neurological pathologies in humans, is clearly making us reconsider their undeserved reputation as being unexceptional enzymes.
Collapse
Affiliation(s)
- Anna H Bizard
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| |
Collapse
|
4
|
Szafran MJ, Strzałka A, Jakimowicz D. A highly processive actinobacterial topoisomerase I - thoughts on Streptomyces' demand for an enzyme with a unique C-terminal domain. MICROBIOLOGY-SGM 2019; 166:120-128. [PMID: 31390324 PMCID: PMC7398561 DOI: 10.1099/mic.0.000841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Topoisomerase I (TopA) is an essential enzyme that is required to remove excess negative supercoils from chromosomal DNA. Actinobacteria encode unusual TopA homologues with a unique C-terminal domain that contains lysine repeats and confers high enzyme processivity. Interestingly, the longest stretch of lysine repeats was identified in TopA from Streptomyces, environmental bacteria that undergo complex differentiation and produce a plethora of secondary metabolites. In this review, we aim to discuss potential advantages of the lysine repeats in Streptomyces TopA. We speculate that the chromosome organization, transcriptional regulation and lifestyle of these species demand a highly processive but also fine-tuneable relaxase. We hypothesize that the unique TopA provides flexible control of chromosomal topology and globally regulates gene expression.
Collapse
Affiliation(s)
- Marcin J Szafran
- Laboratory of Molecular Microbiology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Agnieszka Strzałka
- Laboratory of Molecular Microbiology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Dagmara Jakimowicz
- Laboratory of Molecular Microbiology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| |
Collapse
|
5
|
Hevener K, Verstak TA, Lutat KE, Riggsbee DL, Mooney JW. Recent developments in topoisomerase-targeted cancer chemotherapy. Acta Pharm Sin B 2018; 8:844-861. [PMID: 30505655 PMCID: PMC6251812 DOI: 10.1016/j.apsb.2018.07.008] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 07/18/2018] [Accepted: 07/18/2018] [Indexed: 12/17/2022] Open
Abstract
The DNA topoisomerase enzymes are essential to cell function and are found ubiquitously in all domains of life. The various topoisomerase enzymes perform a wide range of functions related to the maintenance of DNA topology during DNA replication, and transcription are the targets of a wide range of antimicrobial and cancer chemotherapeutic agents. Natural product-derived agents, such as the camptothecin, anthracycline, and podophyllotoxin drugs, have seen broad use in the treatment of many types of cancer. Selective targeting of the topoisomerase enzymes for cancer treatment continues to be a highly active area of basic and clinical research. The focus of this review will be to summarize the current state of the art with respect to clinically used topoisomerase inhibitors for targeted cancer treatment and to discuss the pharmacology and chemistry of promising new topoisomerase inhibitors in clinical and pre-clinical development.
Collapse
Affiliation(s)
- KirkE. Hevener
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | | | | | | |
Collapse
|
6
|
Strzalka A, Szafran MJ, Strick T, Jakimowicz D. C-terminal lysine repeats in Streptomyces topoisomerase I stabilize the enzyme-DNA complex and confer high enzyme processivity. Nucleic Acids Res 2017; 45:11908-11924. [PMID: 28981718 PMCID: PMC5714199 DOI: 10.1093/nar/gkx827] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/06/2017] [Indexed: 12/12/2022] Open
Abstract
Streptomyces topoisomerase I (TopA) exhibits exceptionally high processivity. The enzyme, as other actinobacterial topoisomerases I, differs from its bacterial homologs in its C-terminal domain (CTD). Here, bioinformatics analyses established that the presence of lysine repeats is a characteristic feature of actinobacterial TopA CTDs. Streptomyces TopA contains the longest stretch of lysine repeats, which terminate with acidic amino acids. DNA-binding studies revealed that the lysine repeats stabilized the TopA–DNA complex, while single-molecule experiments showed that their elimination impaired enzyme processivity. Streptomyces coelicolor TopA processivity could not be restored by fusion of its N-terminal domain (NTD) with the Escherichia coli TopA CTD. The hybrid protein could not re-establish the distribution of multiple chromosomal copies in Streptomyces hyphae impaired by TopA depletion. We expected that the highest TopA processivity would be required during the growth of multigenomic sporogenic hyphae, and indeed, the elimination of lysine repeats from TopA disturbed sporulation. We speculate that the interaction of the lysine repeats with DNA allows the stabilization of the enzyme–DNA complex, which is additionally enhanced by acidic C-terminal amino acids. The complex stabilization, which may be particularly important for GC-rich chromosomes, enables high enzyme processivity. The high processivity of TopA allows rapid topological changes in multiple chromosomal copies during Streptomyces sporulation.
Collapse
Affiliation(s)
- Agnieszka Strzalka
- Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14A, 50-383 Wroclaw, Poland
| | - Marcin J Szafran
- Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14A, 50-383 Wroclaw, Poland
| | - Terence Strick
- Institut Jacques Monod, CNRS UMR 7592, University Paris Diderot, Sorbonne Paris Cite, F-75205 Paris, France
| | - Dagmara Jakimowicz
- Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14A, 50-383 Wroclaw, Poland
| |
Collapse
|
7
|
Advances in the Chemistry of Natural and Semisynthetic Topoisomerase I/II Inhibitors. STUDIES IN NATURAL PRODUCTS CHEMISTRY 2017. [DOI: 10.1016/b978-0-444-63929-5.00002-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
|
8
|
Ravishankar S, Ambady A, Awasthy D, Mudugal NV, Menasinakai S, Jatheendranath S, Guptha S, Sharma S, Balakrishnan G, Nandishaiah R, Ramachandran V, Eyermann CJ, Reck F, Rudrapatna S, Sambandamurthy VK, Sharma UK. Genetic and chemical validation identifies Mycobacterium tuberculosis topoisomerase I as an attractive anti-tubercular target. Tuberculosis (Edinb) 2015; 95:589-98. [PMID: 26073894 DOI: 10.1016/j.tube.2015.05.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 04/30/2015] [Accepted: 05/13/2015] [Indexed: 12/21/2022]
Abstract
DNA topoisomerases perform the essential function of maintaining DNA topology in prokaryotes. DNA gyrase, an essential enzyme that introduces negative supercoils, is a clinically validated target. However, topoisomerase I (Topo I), an enzyme responsible for DNA relaxation has received less attention as an antibacterial target, probably due to the ambiguity over its essentiality in many organisms. The Mycobacterium tuberculosis genome harbors a single topA gene with no obvious redundancy in its function suggesting an essential role. The topA gene could be inactivated only in the presence of a complementing copy of the gene in M. tuberculosis. Furthermore, down-regulation of topA in a genetically engineered strain of M. tuberculosis resulted in loss of bacterial viability which correlated with a concomitant depletion of intracellular Topo I levels. The topA knockdown strain of M. tuberculosis failed to establish infection in a murine model of TB and was cleared from lungs in two months post infection. Phenotypic screening of a Topo I overexpression strain led to the identification of an inhibitor, thereby providing chemical validation of this target. Thus, our work confirms the attractiveness of Topo I as an anti-mycobacterial target.
Collapse
Affiliation(s)
- Sudha Ravishankar
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India.
| | - Anisha Ambady
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Disha Awasthy
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | | | | | - Supreeth Guptha
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | - Sreevalli Sharma
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | - Radha Nandishaiah
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | - Charles J Eyermann
- AstraZeneca Infection, Innovative Medicines, 35 Gatehouse Drive, Waltham, MA 02451, United States
| | - Folkert Reck
- AstraZeneca Infection, Innovative Medicines, 35 Gatehouse Drive, Waltham, MA 02451, United States
| | - Suresh Rudrapatna
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| | | | - Umender K Sharma
- AstraZeneca India Pvt. Ltd., Bellary Road, Hebbal, Bangalore 560024, India
| |
Collapse
|
9
|
Ghosh S, Mallick B, Nagaraja V. Direct regulation of topoisomerase activity by a nucleoid-associated protein. Nucleic Acids Res 2014; 42:11156-65. [PMID: 25200077 PMCID: PMC4176182 DOI: 10.1093/nar/gku804] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The topological homeostasis of bacterial chromosomes is maintained by the balance between compaction and the topological organization of genomes. Two classes of proteins play major roles in chromosome organization: the nucleoid-associated proteins (NAPs) and topoisomerases. The NAPs bind DNA to compact the chromosome, whereas topoisomerases catalytically remove or introduce supercoils into the genome. We demonstrate that HU, a major NAP of Mycobacterium tuberculosis specifically stimulates the DNA relaxation ability of mycobacterial topoisomerase I (TopoI) at lower concentrations but interferes at higher concentrations. A direct physical interaction between M. tuberculosis HU (MtHU) and TopoI is necessary for enhancing enzyme activity both in vitro and in vivo. The interaction is between the amino terminal domain of MtHU and the carboxyl terminal domain of TopoI. Binding of MtHU did not affect the two catalytic trans-esterification steps but enhanced the DNA strand passage, requisite for the completion of DNA relaxation, a new mechanism for the regulation of topoisomerase activity. An interaction-deficient mutant of MtHU was compromised in enhancing the strand passage activity. The species-specific physical and functional cooperation between MtHU and TopoI may be the key to achieve the DNA relaxation levels needed to maintain the optimal superhelical density of mycobacterial genomes.
Collapse
Affiliation(s)
- Soumitra Ghosh
- Department of Microbiology and Cell biology, Indian Institute of Science, Bangalore 560012, India
| | - Bratati Mallick
- Department of Microbiology and Cell biology, Indian Institute of Science, Bangalore 560012, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell biology, Indian Institute of Science, Bangalore 560012, India Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| |
Collapse
|
10
|
Dezhenkova LG, Tsvetkov VB, Shtil AA. Topoisomerase I and II inhibitors: chemical structure, mechanisms of action and role in cancer chemotherapy. RUSSIAN CHEMICAL REVIEWS 2014. [DOI: 10.1070/rc2014v083n01abeh004363] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
11
|
Sakai Y, Ogawa N, Shimomura Y, Fujii T. A 2,4-dichlorophenoxyacetic acid degradation plasmid pM7012 discloses distribution of an unclassified megaplasmid group across bacterial species. MICROBIOLOGY-SGM 2014; 160:525-536. [PMID: 24440834 DOI: 10.1099/mic.0.074369-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Analysis of the complete nucleotide sequence of plasmid pM7012 from 2,4-dichlorophenoxyacetic-acid (2,4-D)-degrading bacterium Burkholderia sp. M701 revealed that the plasmid had 582 142 bp, with 541 putative protein-coding sequences and 39 putative tRNA genes for the transport of the standard 20 aa. pM7012 contains sequences homologous to the regions involved in conjugal transfer and plasmid maintenance found in plasmids byi_2p from Burkholderia sp. YI23 and pBVIE01 from Burkholderia sp. G4. No relaxase gene was found in any of these plasmids, although genes for a type IV secretion system and type IV coupling proteins were identified. Plasmids with no relaxase gene have been classified as non-mobile plasmids. However, nucleotide sequences with a high level of similarity to the genes for plasmid transfer, plasmid maintenance, 2,4-D degradation and arsenic resistance contained on pM7012 were also detected in eight other megaplasmids (~600 or 900 kb) found in seven Burkholderia strains and a strain of Cupriavidus, which were isolated as 2,4-D-degrading bacteria in Japan and the United States. These results suggested that the 2,4-D degradation megaplasmids related to pM7012 are mobile and distributed across various bacterial species worldwide, and that the plasmid group could be distinguished from known mobile plasmid groups.
Collapse
Affiliation(s)
- Yoriko Sakai
- Environmental Biofunction Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan
| | - Naoto Ogawa
- Faculty of Agriculture, Shizuoka University, 836 Ohya, Surugaku, Shizuoka 422-8529, Japan
| | - Yumi Shimomura
- Environmental Biofunction Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan
| | - Takeshi Fujii
- Environmental Biofunction Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan
| |
Collapse
|
12
|
Topoisomerase I (TopA) is recruited to ParB complexes and is required for proper chromosome organization during Streptomyces coelicolor sporulation. J Bacteriol 2013; 195:4445-55. [PMID: 23913317 DOI: 10.1128/jb.00798-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Streptomyces species are bacteria that resemble filamentous fungi in their hyphal mode of growth and sporulation. In Streptomyces coelicolor, the conversion of multigenomic aerial hyphae into chains of unigenomic spores requires synchronized septation accompanied by segregation of tens of chromosomes into prespore compartments. The chromosome segregation is dependent on ParB protein, which assembles into an array of nucleoprotein complexes in the aerial hyphae. Here, we report that nucleoprotein ParB complexes are bound in vitro and in vivo by topoisomerase I, TopA, which is the only topoisomerase I homolog found in S. coelicolor. TopA cannot be eliminated, and its depletion inhibits growth and blocks sporulation. Surprisingly, sporulation in the TopA-depleted strain could be partially restored by deletion of parB. Furthermore, the formation of regularly spaced ParB complexes, which is a prerequisite for proper chromosome segregation and septation during the development of aerial hyphae, has been found to depend on TopA. We hypothesize that TopA is recruited to ParB complexes during sporulation, and its activity is required to resolve segregating chromosomes.
Collapse
|
13
|
Hong R. Secalonic acid D as a novel DNA topoisomerase I inhibitor from marine lichen-derived fungus Gliocladium sp. T31. PHARMACEUTICAL BIOLOGY 2011; 49:796-799. [PMID: 21495809 DOI: 10.3109/13880209.2010.548817] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
CONTEXT DNA topoisomerase I (topo I) is an essential enzyme which regulates the conformational changes in DNA topology by cleaving and rejoining DNA strands during normal cell growth. The inhibitors of topo I represent a major class of anticancer drugs. In our projects to isolate new anticancer agents from marine-derived fungi, secalonic acid D (SAD) with inhibitory activity on topo I was isolated from the fermentation broth of marine lichen-derived fungus Gliocladium sp. T31, which was collected from marine sediments in South Pole. OBJECTIVE The inhibitory activity of SAD on topo I was investigated for the first time. MATERIALS AND METHODS The inhibitory effect of SAD on topo I was determined via in vitro supercoil relaxation assays and electrophoretic mobility shift assay (EMSA) using plasmid substrate, pBR322. RESULTS SAD displays a considerable inhibition on topo I in a dose-dependent manner with the minimum inhibitory concentration (MIC) of 0.4 µM. Unlike the prototypic DNA topo I poison camptothecin (CPT), SAD inhibits the binding of topo I to DNA but does not induce the formation of topo I-DNA covalent complexes. DISCUSSION AND CONCLUSION SAD is an excellent topo I inhibitor and thus a significantly potential anticancer candidate.
Collapse
Affiliation(s)
- Ren Hong
- Beijing Key Laboratory of Plant Resource Research and Development, College of Chemical and Environmental Engineering, Beijing Technology and Business University, Beijing, China.
| |
Collapse
|