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Gopalakrishnan V, Roy U, Srivastava S, Kariya KM, Sharma S, Javedakar SM, Choudhary B, Raghavan SC. Delineating the mechanism of fragility at BCL6 breakpoint region associated with translocations in diffuse large B cell lymphoma. Cell Mol Life Sci 2024; 81:21. [PMID: 38196006 PMCID: PMC11072719 DOI: 10.1007/s00018-023-05042-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 11/05/2023] [Accepted: 11/07/2023] [Indexed: 01/11/2024]
Abstract
BCL6 translocation is one of the most common chromosomal translocations in cancer and results in its enhanced expression in germinal center B cells. It involves the fusion of BCL6 with any of its twenty-six Ig and non-Ig translocation partners associated with diffuse large B cell lymphoma (DLBCL). Despite being discovered long back, the mechanism of BCL6 fragility is largely unknown. Analysis of the translocation breakpoints in 5' UTR of BCL6 reveals the clustering of most of the breakpoints around a region termed Cluster II. In silico analysis of the breakpoint cluster sequence identified sequence motifs that could potentially fold into non-B DNA. Results revealed that the Cluster II sequence folded into overlapping hairpin structures and identified sequences that undergo base pairing at the stem region. Further, the formation of cruciform DNA blocked DNA replication. The sodium bisulfite modification assay revealed the single-strandedness of the region corresponding to hairpin DNA in both strands of the genome. Further, we report the formation of intramolecular parallel G4 and triplex DNA, at Cluster II. Taken together, our studies reveal that multiple non-canonical DNA structures exist at the BCL6 cluster II breakpoint region and contribute to the fragility leading to BCL6 translocation in DLBCL patients.
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Affiliation(s)
- Vidya Gopalakrishnan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, 560 100, India
- Department of Zoology, St. Joseph's College (Autonomous), Irinjalakuda, Kerala, 680121, India
| | - Urbi Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Shikha Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
- Department of Bioscience and Biotechnology, Banasthali Vidyapith, Tonk, Rajasthan, 304022, India
| | - Khyati M Kariya
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Shivangi Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Saniya M Javedakar
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Electronics City, Bangalore, 560 100, India.
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India.
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2
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Ferguson L, Upton HE, Pimentel SC, Mok A, Lareau LF, Collins K, Ingolia NT. Streamlined and sensitive mono- and di-ribosome profiling in yeast and human cells. Nat Methods 2023; 20:1704-1715. [PMID: 37783882 PMCID: PMC11276118 DOI: 10.1038/s41592-023-02028-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 08/23/2023] [Indexed: 10/04/2023]
Abstract
Ribosome profiling has unveiled diverse regulation and perturbations of translation through a transcriptome-wide survey of ribosome occupancy, read out by sequencing of ribosome-protected messenger RNA fragments. Generation of ribosome footprints and their conversion into sequencing libraries is technically demanding and sensitive to biases that distort the representation of physiological ribosome occupancy. We address these challenges by producing ribosome footprints with P1 nuclease rather than RNase I and replacing RNA ligation with ordered two-template relay, a single-tube protocol for sequencing library preparation that incorporates adaptors by reverse transcription. Our streamlined approach reduced sequence bias and enhanced enrichment of ribosome footprints relative to ribosomal RNA. Furthermore, P1 nuclease preserved distinct juxtaposed ribosome complexes informative about yeast and human ribosome fates during translation initiation, stalling and termination. Our optimized methods for mRNA footprint generation and capture provide a richer translatome profile with low input and fewer technical challenges.
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Affiliation(s)
- Lucas Ferguson
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- Center for Computational Biology, University of California, Berkeley, CA, USA.
| | - Heather E Upton
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Sydney C Pimentel
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Amanda Mok
- Center for Computational Biology, University of California, Berkeley, CA, USA
| | - Liana F Lareau
- Center for Computational Biology, University of California, Berkeley, CA, USA
- Department of Bioengineering, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
| | - Kathleen Collins
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA.
| | - Nicholas T Ingolia
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA.
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3
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Kumari N, Antil H, Kumari S, Raghavan SC. Deficiency of ligase IV leads to reduced NHEJ, accumulation of DNA damage, and can sensitize cells to cancer therapeutics. Genomics 2023; 115:110731. [PMID: 37871849 DOI: 10.1016/j.ygeno.2023.110731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 09/14/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023]
Abstract
Ligase IV is a key enzyme involved during DNA double-strand breaks (DSBs) repair through nonhomologous end joining (NHEJ). However, in contrast to Ligase IV deficient mouse cells, which are embryonic lethal, Ligase IV deficient human cells, including pre-B cells, are viable. Using CRISPR-Cas9 mediated genome editing, we have generated six different LIG4 mutants in cervical cancer and normal kidney epithelial cell lines. While the LIG4 mutant cells showed a significant reduction in NHEJ, joining mediated through microhomology-mediated end joining (MMEJ) and homologous recombination (HR) were significantly high. The reduced NHEJ joining activity was restored by adding purified Ligase IV/XRCC4. Accumulation of DSBs and reduced cell viability were observed in LIG4 mutant cells. LIG4 mutant cells exhibited enhanced sensitivity towards DSB-inducing agents such as ionizing radiation (IR) and etoposide. More importantly, the LIG4 mutant of cervical cancer cells showed increased sensitivity towards FDA approved drugs such as Carboplatin, Cisplatin, Paclitaxel, Doxorubicin, and Bleomycin used for cervical cancer treatment. These drugs, in combination with IR showed enhanced cancer cell death in the background of LIG4 gene mutation. Thus, our study reveals that mutation in LIG4 results in compromised NHEJ, leading to sensitization of cervical cancer cells towards currently used cancer therapeutics.
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Affiliation(s)
- Nitu Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Himanshu Antil
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Susmita Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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4
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Foley W, Arman H, Musie GT. Homodinuclear copper(II) and zinc(II) complexes of a carboxylate-rich ligand as synthetic mimics of phosphoester hydrolase in aqueous solutions. J Inorg Biochem 2021; 225:111589. [PMID: 34530333 DOI: 10.1016/j.jinorgbio.2021.111589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/14/2021] [Accepted: 08/18/2021] [Indexed: 11/28/2022]
Abstract
The synthesis, characterization and catalytic activities of two homodinuclear Cu(II) and Zn(II) complexes of a carboxylate-rich ligand, N,N'-Bis[2-carboxybenzomethyl]-N,N' -Bis[carboxymethyl]-1,3-diaminopropan-2-ol (H5ccdp) ligand towards the hydrolysis of (p-nitrophenyl phosphate) (PNPP) and bis(p-nitrophenyl) phosphate (BNPP) substrates in aqueous systems are described. Kinetic investigations were carried out using UV-Vis spectrophotometric techniques at 25 °C and 37 °C and different pH (7-10) conditions. The kinetic studies revealed that the turnover rate (kcat) values among the PNPP hydrolysis systems, the highest and the lowest kcat values were displayed by [Cu2(ccdp)(μ-OAc)]2- at 2.34 × 10-6 s-1 (pH 8 and 37 °C) and 2.13 × 10-8 s-1 (pH 8 and 25 °C), respectively. However, similar comparisons among the BNPP hydrolysis revealed that highest and the lowest kcat values were displayed by [Zn2(ccdp)(μ-OAc)]2- at 4.64 × 10-8 s-1 (pH 9 and 37 °C) and 2.38 × 10-9 (pH 9 and 25 °C). Significantly enough, the catalyst-substrate adduct species containing a metal bound PNPP and BNPP have been detected by ESI-MS techniques. Additionally, a PNPP-bound copper complex has been isolated and crystalized using single crystal X-ray diffraction technique. Based on the structural and activity information obtained in this study, reaction mechanisms for the hydrolysis of PNPP have been proposed.
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Affiliation(s)
- William Foley
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Hadi Arman
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Ghezai T Musie
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States.
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Ray U, Sharma S, Kapoor I, Kumari S, Gopalakrishnan V, Vartak SV, Kumari N, Varshney U, Raghavan SC. G4 DNA present at human telomeric DNA contributes toward reduced sensitivity to γ-radiation induced oxidative damage, but not bulky adduct formation. Int J Radiat Biol 2021; 97:1166-1180. [PMID: 34259614 DOI: 10.1080/09553002.2021.1955997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/11/2021] [Accepted: 06/23/2021] [Indexed: 12/15/2022]
Abstract
PURPOSE DNA, the hereditary material of a human cell generally exists as Watson-Crick base paired double-stranded B-DNA. Studies suggest that DNA can also exist in non-B forms, such as four stranded G-quadruplexes (G4 DNA). Recently, our studies revealed that the regions of DNA that can fold into G-quadruplex structures are less sensitive to ionizing radiation (IR) compared to B-DNA. Importantly, we reported that the planar G-quartet of a G4 structure is shielded from radiation induced DNA breaks, while the single- and double-stranded DNA regions remained susceptible. Thus, in the present study, we investigate whether telomeric repeat DNA present at the end of telomere, known to fold into G4 DNA can protect from radiation induced damages including strand breaks, oxidation of purines and bulky adduct formation on DNA. MATERIALS AND METHODS For plasmid irradiation assay, plasmids containing human telomeric repeat DNA sequence TTAGGG (0.8 kb or 1.8 kb) were irradiated with increasing doses of IR along with appropriate control plasmids and products were resolved on 1% agarose gel. Radioprotection was evaluated based on extent of conversion of supercoiled to nicked or linear forms of the DNA following irradiation. Formation of G-quadruplex structure on supercoiled DNA was evaluated based on circular dichroism (CD) spectroscopy studies. Cleavage of radiation induced oxidative damage and extent of formation of nicks was further evaluated using base and nucleotide excision repair proteins. RESULTS Results from CD studies showed that the plasmid DNA harboring human telomeric repeats (TTAGGG) can fold into G-quadruplex DNA structures. Further, results showed that human telomeric repeat sequence when present on a plasmid can protect the plasmid DNA against IR induced DNA strand breaks, unlike control plasmids bearing random DNA sequence. CONCLUSIONS Human telomeric repeat sequence when present on plasmids can fold into G-quadruplex DNA structures, and can protect the DNA against IR induced DNA strand breaks and oxidative damage. These results in conjunction with our previous studies suggest that telomeric repeat sequence imparts less sensitivity to IR and thus telomeres of chromosomes are protected from radiation.
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Affiliation(s)
- Ujjayinee Ray
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Shivangi Sharma
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Indu Kapoor
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Susmita Kumari
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Vidya Gopalakrishnan
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
- Department of Zoology, St. Joseph's College, Irinjalakuda, India
| | - Supriya V Vartak
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Nitu Kumari
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bengaluru, India
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6
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Javadekar SM, Yadav R, Raghavan SC. DNA structural basis for fragility at peak III of BCL2 major breakpoint region associated with t(14;18) translocation. Biochim Biophys Acta Gen Subj 2017; 1862:649-659. [PMID: 29246583 DOI: 10.1016/j.bbagen.2017.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/23/2017] [Accepted: 12/07/2017] [Indexed: 12/23/2022]
Abstract
Maintaining genome integrity is crucial for normal cellular functions. DNA double-strand breaks (DSBs), when unrepaired, can potentiate chromosomal translocations. t(14;18) translocation involving BCL2 gene on chromosome 18 and IgH loci at chromosome 14, could lead to follicular lymphoma. Molecular basis for fragility of translocation breakpoint regions is an active area of investigation. Previously, formation of non-B DNA structures like G-quadruplex, triplex, B/A transition were investigated at peak I of BCL2 major breakpoint region (MBR); however, it is less understood at peak III. In vitro gel shift assays show faster mobility for MBR peak III sequences, unlike controls. CD studies of peak III sequences reveal a spectral pattern different from B-DNA. Although complementary C-rich stretches exhibit single-strandedness, corresponding guanine-rich sequences do not show DMS protection, ruling out G-quadruplex and triplex DNA. Extrachromosomal assay indicates that peak III halts transcription, unlike its mutated version. Taken together, multiple lines of evidence suggest formation of potential cruciform DNA structure at MBR peak III, which was also supported by in silico studies. Thus, our study reveals formation of non-B DNA structure which could be a basis for fragility at BCL2 breakpoint regions, eventually leading to chromosomal translocations.
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Affiliation(s)
- Saniya M Javadekar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Rakhee Yadav
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
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7
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Das K, Srivastava M, Raghavan SC. GNG Motifs Can Replace a GGG Stretch during G-Quadruplex Formation in a Context Dependent Manner. PLoS One 2016; 11:e0158794. [PMID: 27414642 PMCID: PMC4945072 DOI: 10.1371/journal.pone.0158794] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/22/2016] [Indexed: 12/13/2022] Open
Abstract
G-quadruplexes are one of the most commonly studied non-B DNA structures. Generally, these structures are formed using a minimum of 4, three guanine tracts, with connecting loops ranging from one to seven. Recent studies have reported deviation from this general convention. One such deviation is the involvement of bulges in the guanine tracts. In this study, guanines along with bulges, also referred to as GNG motifs have been extensively studied using recently reported HOX11 breakpoint fragile region I as a model template. By strategic mutagenesis approach we show that the contribution from continuous G-tracts may be dispensible during G-quadruplex formation when such motifs are flanked by GNGs. Importantly, the positioning and number of GNG/GNGNG can also influence the formation of G-quadruplexes. Further, we assessed three genomic regions from HIF1 alpha, VEGF and SHOX gene for G-quadruplex formation using GNG motifs. We show that HIF1 alpha sequence harbouring GNG motifs can fold into intramolecular G-quadruplex. In contrast, GNG motifs in mutant VEGF sequence could not participate in structure formation, suggesting that the usage of GNG is context dependent. Importantly, we show that when two continuous stretches of guanines are flanked by two independent GNG motifs in a naturally occurring sequence (SHOX), it can fold into an intramolecular G-quadruplex. Finally, we show the specific binding of G-quadruplex binding protein, Nucleolin and G-quadruplex antibody, BG4 to SHOX G-quadruplex. Overall, our study provides novel insights into the role of GNG motifs in G-quadruplex structure formation which may have both physiological and pathological implications.
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Affiliation(s)
- Kohal Das
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Mrinal Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
- * E-mail:
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8
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Raveendran D, Raghavan SC. Biochemical Characterization of Nonamer Binding Domain of RAG1 Reveals its Thymine Preference with Respect to Length and Position. Sci Rep 2016; 6:19091. [PMID: 26742581 PMCID: PMC4705477 DOI: 10.1038/srep19091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/20/2015] [Indexed: 12/15/2022] Open
Abstract
RAG complex consisting of RAG1 and RAG2 is a site-specific endonuclease responsible for the generation of antigen receptor diversity. It cleaves recombination signal sequence (RSS), comprising of conserved heptamer and nonamer. Nonamer binding domain (NBD) of RAG1 plays a central role in the recognition of RSS. To investigate the DNA binding properties of the domain, NBD of murine RAG1 was cloned, expressed and purified. Electrophoretic mobility shift assays showed that NBD binds with high affinity to nonamer in the context of 12/23 RSS or heteroduplex DNA. NBD binding was specific to thymines when single stranded DNA containing poly A, C, G or T were used. Biolayer interferometry studies showed that poly T binding to NBD was robust and comparable to that of 12RSS. More than 23 nt was essential for NBD binding at homothymidine stretches. On a double-stranded DNA, NBD could bind to A:T stretches, but not G:C or random sequences. Although NBD is indispensable for sequence specific activity of RAGs, external supplementation of purified nonamer binding domain to NBD deleted cRAG1/cRAG2 did not restore its activity, suggesting that the overall domain architecture of RAG1 is important. Therefore, we define the sequence requirements of NBD binding to DNA.
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Affiliation(s)
- Deepthi Raveendran
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012, India
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9
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A non-B DNA can replace heptamer of V(D)J recombination when present along with a nonamer: implications in chromosomal translocations and cancer. Biochem J 2013; 448:115-25. [PMID: 22891626 DOI: 10.1042/bj20121031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The RAG (recombination-activating gene) complex is responsible for the generation of antigen receptor diversity by acting as a sequence-specific nuclease. Recent studies have shown that it also acts as a structure-specific nuclease. However, little is known about the factors regulating this activity at the genomic level. We show in the present study that the proximity of a V(D)J nonamer to heteroduplex DNA significantly increases RAG cleavage and binding efficiencies at physiological concentrations of MgCl(2). The position of the nonamer with respect to heteroduplex DNA was important, but not orientation. A spacer length of 18 bp between the nonamer and mismatch was optimal for RAG-mediated DNA cleavage. Mutations to the sequence of the nonamer and deletion of the nonamer-binding domain of RAG1 reinforced the role of the nonamer in the enhancement in RAG cleavage. Interestingly, partial mutation of the nonamer did not significantly reduce RAG cleavage on heteroduplex DNA, suggesting that even cryptic nonamers were sufficient to enhance RAG cleavage. More importantly, we show that the fragile region involved in chromosomal translocations associated with BCL2 (B-cell lymphoma 2) can be cleaved by RAGs following a nonamer-dependent mechanism. Hence our results from the present study suggest that a non-B DNA can replace the heptamer of RSS (recombination signal sequence) when present adjacent to nonamers, explaining the generation of certain chromosomal translocations in lymphoid malignancies.
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Ko CY, Lai YL, Liu WY, Lin CH, Chen YT, Chen LFO, Lin TY, Shaw JF. Arabidopsis ENDO2: its catalytic role and requirement of N-glycosylation for function. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:5169-5179. [PMID: 22506810 DOI: 10.1021/jf300945c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Arabidopsis thaliana At1g68290 gene encoding an endonuclease was isolated and designated ENDO2, which was cloned into a binary vector to overexpress ENDO2 with a C-terminal 6 × His-tag in A. thaliana. Our Arabidopsis transgenic lines harboring 35SP::ENDO2 produced stable active enzyme with high yield. The protein was affinity purified from transgenic plants, and its identity was confirmed by liquid chromatography-mass spectrometry and automatic Edman degradation. ENDO2 enzyme digests RNA, ssDNA, and dsDNA, with a substrate preference for ssDNA and RNA. The activity toward ssDNA (361.7 U/mg) is greater than its dsDNase activity (14.1 U/mg) at neutral pH. ENDO2 effectively cleaves mismatch regions in heteroduplex DNA containing single base pair mismatches or insertion/deletion bases and can be applied to high-throughput detection of single base mutation. Our data also validated that the removal of sugar groups from ENDO2 strongly affects its enzymatic stability and activity.
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Affiliation(s)
- Chia-Yun Ko
- Institute of Bioinformatics and Structural Biology, National Tsing Hua University , Hsinchu, 30013, Taiwan
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Chiruvella KK, Sebastian R, Sharma S, Karande AA, Choudhary B, Raghavan SC. Time-Dependent Predominance of Nonhomologous DNA End-Joining Pathways during Embryonic Development in Mice. J Mol Biol 2012; 417:197-211. [DOI: 10.1016/j.jmb.2012.01.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 01/18/2012] [Accepted: 01/20/2012] [Indexed: 12/26/2022]
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12
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Naik AK, Raghavan SC. Differential reaction kinetics, cleavage complex formation, and nonamer binding domain dependence dictate the structure-specific and sequence-specific nuclease activity of RAGs. J Mol Biol 2011; 415:475-88. [PMID: 22119487 DOI: 10.1016/j.jmb.2011.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/27/2011] [Accepted: 11/01/2011] [Indexed: 11/28/2022]
Abstract
During V(D)J recombination, RAG (recombination-activating gene) complex cleaves DNA based on sequence specificity. Besides its physiological function, RAG has been shown to act as a structure-specific nuclease. Recently, we showed that the presence of cytosine within the single-stranded region of heteroduplex DNA is important when RAGs cleave on DNA structures. In the present study, we report that heteroduplex DNA containing a bubble region can be cleaved efficiently when present along with a recombination signal sequence (RSS) in cis or trans configuration. The sequence of the bubble region influences RAG cleavage at RSS when present in cis. We also find that the kinetics of RAG cleavage differs between RSS and bubble, wherein RSS cleavage reaches maximum efficiency faster than bubble cleavage. In addition, unlike RSS, RAG cleavage at bubbles does not lead to cleavage complex formation. Finally, we show that the "nonamer binding region," which regulates RAG cleavage on RSS, is not important during RAG activity in non-B DNA structures. Therefore, in the current study, we identify the possible mechanism by which RAG cleavage is regulated when it acts as a structure-specific nuclease.
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Affiliation(s)
- Abani Kanta Naik
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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13
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Sharma S, Choudhary B, Raghavan SC. Efficiency of nonhomologous DNA end joining varies among somatic tissues, despite similarity in mechanism. Cell Mol Life Sci 2011; 68:661-76. [PMID: 20680388 PMCID: PMC11114952 DOI: 10.1007/s00018-010-0472-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 07/07/2010] [Accepted: 07/16/2010] [Indexed: 01/09/2023]
Abstract
Failure to repair DNA double-strand breaks (DSBs) can lead to cell death or cancer. Although nonhomologous end joining (NHEJ) has been studied extensively in mammals, little is known about it in primary tissues. Using oligomeric DNA mimicking endogenous DSBs, NHEJ in cell-free extracts of rat tissues were studied. Results show that efficiency of NHEJ is highest in lungs compared to other somatic tissues. DSBs with compatible and blunt ends joined without modifications, while noncompatible ends joined with minimal alterations in lungs and testes. Thymus exhibited elevated joining, followed by brain and spleen, which could be correlated with NHEJ gene expression. However, NHEJ efficiency was poor in terminally differentiated organs like heart, kidney and liver. Strikingly, NHEJ junctions from these tissues also showed extensive deletions and insertions. Hence, for the first time, we show that despite mode of joining being generally comparable, efficiency of NHEJ varies among primary tissues of mammals.
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Affiliation(s)
- Sheetal Sharma
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012 India
| | - Bibha Choudhary
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012 India
- Manipal Institute of Regenerative Medicine, Manipal University, Bangalore, 560 071 India
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560 012 India
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14
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Liao RZ, Yu JG, Himo F. Phosphate mono- and diesterase activities of the trinuclear zinc enzyme nuclease P1--insights from quantum chemical calculations. Inorg Chem 2010; 49:6883-8. [PMID: 20604512 DOI: 10.1021/ic100266n] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nuclease P1 is a trinuclear zinc enzyme that catalyzes the hydrolysis of single-stranded DNA and RNA. Density functional calculations are used to elucidate the reaction mechanism of this enzyme with a model of the active site designed on the basis of the X-ray crystal structure. 2-Tetrahydrofuranyl phosphate and methyl 2-tetrahydrofuranyl phosphate substrates are used to explore the phosphomonoesterase and phosphodiesterase activities of this enzyme, respectively. The calculations reveal that for both activities, a bridging hydroxide performs an in-line attack on the phosphorus center, resulting in inversion of the configuration. Simultaneously, the P-O bond is cleaved, and Zn2 stabilizes the negative charge of the leaving alkoxide anion and assists its departure. All three zinc ions, together with Arg48, provide electrostatic stabilization to the penta-coordinated transition state, thereby lowering the reaction barrier.
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Affiliation(s)
- Rong-Zhen Liao
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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Underwood JG, Uzilov AV, Katzman S, Onodera CS, Mainzer JE, Mathews DH, Lowe TM, Salama SR, Haussler D. FragSeq: transcriptome-wide RNA structure probing using high-throughput sequencing. Nat Methods 2010; 7:995-1001. [PMID: 21057495 PMCID: PMC3247016 DOI: 10.1038/nmeth.1529] [Citation(s) in RCA: 242] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 10/13/2010] [Indexed: 01/07/2023]
Abstract
Previous efforts to determine structures of non-coding RNA (ncRNA) probed only one RNA at a time with enzymes and chemicals, using gel electrophoresis to identify reactive positions. To accelerate RNA structure inference, we have developed FragSeq, a high-throughput RNA structure probing method that uses high-throughput RNA sequencing on fragments generated by nuclease P1, which specifically cleaves single stranded nucleic acids. In experiments probing the entire mouse nuclear transcriptome, we show that we can accurately and simultaneously map single-stranded regions (ssRNA) in multiple ncRNAs with known structure. We carried out probing in two cell types to demonstrate reproducibility. We also identified and experimentally validated structured regions in ncRNAs never previously probed.
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Affiliation(s)
- Jason G Underwood
- Howard Hughes Medical Institute, University of California Santa Cruz, Santa Cruz, California, USA
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16
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Nambiar M, Goldsmith G, Moorthy BT, Lieber MR, Joshi MV, Choudhary B, Hosur RV, Raghavan SC. Formation of a G-quadruplex at the BCL2 major breakpoint region of the t(14;18) translocation in follicular lymphoma. Nucleic Acids Res 2010; 39:936-48. [PMID: 20880994 PMCID: PMC3035451 DOI: 10.1093/nar/gkq824] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The t(14;18) translocation in follicular lymphoma is one of the most common chromosomal translocations. Most breaks on chromosome 18 are located at the 3′-UTR of the BCL2 gene and are mainly clustered in the major breakpoint region (MBR). Recently, we found that the BCL2 MBR has a non-B DNA character in genomic DNA. Here, we show that single-stranded DNA modeled from the template strand of the BCL2 MBR, forms secondary structures that migrate faster on native PAGE in the presence of potassium, due to the formation of intramolecular G-quadruplexes. Circular dichroism shows evidence for a parallel orientation for G-quadruplex structures in the template strand of the BCL2 MBR. Mutagenesis and the DMS modification assay confirm the presence of three guanine tetrads in the structure. 1H nuclear magnetic resonance studies further confirm the formation of an intramolecular G-quadruplex and a representative model has been built based on all of the experimental evidence. We also provide data consistent with the possible formation of a G-quadruplex structure at the BCL2 MBR within mammalian cells. In summary, these important features could contribute to the single-stranded character at the BCL2 MBR, thereby contributing to chromosomal fragility.
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Affiliation(s)
- Mridula Nambiar
- Department of Biochemistry, Indian Institute of Science, Bangalore-560 012, India
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17
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Liao RZ, Yu JG, Himo F. Reaction Mechanism of the Trinuclear Zinc Enzyme Phospholipase C: A Density Functional Theory Study. J Phys Chem B 2010; 114:2533-40. [PMID: 20121060 DOI: 10.1021/jp910992f] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Rong-Zhen Liao
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden, and College of Chemistry, Beijing Normal University, Beijing, 100875, People’s Republic of China
| | - Jian-Guo Yu
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden, and College of Chemistry, Beijing Normal University, Beijing, 100875, People’s Republic of China
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden, and College of Chemistry, Beijing Normal University, Beijing, 100875, People’s Republic of China
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18
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Naik AK, Lieber MR, Raghavan SC. Cytosines, but not purines, determine recombination activating gene (RAG)-induced breaks on heteroduplex DNA structures: implications for genomic instability. J Biol Chem 2010; 285:7587-97. [PMID: 20051517 DOI: 10.1074/jbc.m109.089631] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The sequence specificity of the recombination activating gene (RAG) complex during V(D)J recombination has been well studied. RAGs can also act as structure-specific nuclease; however, little is known about the mechanism of its action. Here, we show that in addition to DNA structure, sequence dictates the pattern and efficiency of RAG cleavage on altered DNA structures. Cytosine nucleotides are preferentially nicked by RAGs when present at single-stranded regions of heteroduplex DNA. Although unpaired thymine nucleotides are also nicked, the efficiency is many fold weaker. Induction of single- or double-strand breaks by RAGs depends on the position of cytosines and whether it is present on one or both of the strands. Interestingly, RAGs are unable to induce breaks when adenine or guanine nucleotides are present at single-strand regions. The nucleotide present immediately next to the bubble sequence could also affect RAG cleavage. Hence, we propose "C((d))C((S))C((S))" (d, double-stranded; s, single-stranded) as a consensus sequence for RAG-induced breaks at single-/double-strand DNA transitions. Such a consensus sequence motif is useful for explaining RAG cleavage on other types of DNA structures described in the literature. Therefore, the mechanism of RAG cleavage described here could explain facets of chromosomal rearrangements specific to lymphoid tissues leading to genomic instability.
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Affiliation(s)
- Abani Kanta Naik
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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19
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Lou X, Xiao Y, Wang Y, Mao H, Zhao J. Label-Free Colorimetric Screening of Nuclease Activity and Substrates by Using Unmodified Gold Nanoparticles. Chembiochem 2009; 10:1973-7. [DOI: 10.1002/cbic.200900355] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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