1
|
Krishna MS, Lenka S, Sridevi B, Rao NS, Rao DN, Sarma VVSS, Mithun GG, Prakash TA, Khalap ST, Satelkar NP, Siddharth G, Fernando V. Major sources of sinking particulate organic matter in the western Bay of Bengal. Mar Environ Res 2024; 197:106480. [PMID: 38564848 DOI: 10.1016/j.marenvres.2024.106480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 03/15/2024] [Accepted: 03/26/2024] [Indexed: 04/04/2024]
Abstract
Impacts of river discharge on coastal ocean processes are multi-dimensional. Studies on sinking particle fluxes, composition and their seasonal variability in coastal oceans are very limited. In this study, we investigated the impact of river discharge on seasonal variability in sinking fluxes of total mass, biogenic and lithogenic material in a river-dominated continental margin, western coastal Bay of Bengal. Higher POC, lithogenic and total mass fluxes were found during early southwest monsoon, and are decoupled with peak river discharge and elevated primary production. It is attributed to cross-shelf transport of re-suspended surface sediments from shelf region. Peak river discharge followed by elevated chlorophyll-a suggest nutrients supply though river discharge support primary production. Elemental C:N ratios, δ13C and δ15N results likely suggest that both marine and terrestrial sources contributed to sinking POM, . Overall, higher sinking fluxes during southwest monsoon than rest of the year suggest that seasonal river discharge exerts considerable impact on sinking fluxes in the western coastal Bay of Bengal.
Collapse
Affiliation(s)
- M S Krishna
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India, 530017.
| | - Sreenu Lenka
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India, 530017
| | - B Sridevi
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India, 530017
| | - N S Rao
- ESSO-Indian National Centre for Ocean Information Services, Hyderabad, 500090, India
| | - D N Rao
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India, 530017
| | - V V S S Sarma
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India, 530017
| | - G G Mithun
- CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004
| | - T A Prakash
- CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004
| | - S T Khalap
- CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004
| | - N P Satelkar
- CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004
| | - G Siddharth
- CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004
| | - V Fernando
- CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004
| |
Collapse
|
2
|
Krishna MS, Prasad MHK, Naidu SA, Srikanth G, Reddy NPC, Sarma NS. Export of particulate organic carbon and nitrogen to the northern Indian Ocean by the monsoonal rivers of India. Environ Sci Pollut Res Int 2023; 30:125559-125569. [PMID: 37999850 DOI: 10.1007/s11356-023-30936-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 11/01/2023] [Indexed: 11/25/2023]
Abstract
This study analyses particulate organic carbon (POC) and particulate nitrogen (PN) export from Indian monsoonal rivers to the north Indian Ocean. Indian monsoonal rivers export approximately 1.2 Tg yr-1 (1Tg = 1012 g) of POC and 0.14 Tg yr-1 of PN, with about two-thirds entering the Bay of Bengal (0.8 and 0.1 Tg yr-1, respectively) and the remaining reaches to the Arabian Sea (0.4 and 0.04 Tg yr-1, respectively). Remarkably, just four rivers from northwest India's black soil-dominated regions contribute about half of the total POC and PN exports (0.64 and 0.06 Tg yr-1, respectively). This is due to substantial erosion in these catchments, resulting in suspended matter concentrations averaging 596 ± 252 mg L-1, significantly higher than catchments dominated by red sandy, red loamy and alluvial soils (54 ± 56 mg l-1). In contrast, rivers originating from catchments with heavy precipitation, a tropical wet climate, red loamy soils (with peaty and marshy characteristics), rich tropical wet evergreen and moist deciduous forests, and higher soil organic carbon content yield more POC and PN (1704 ± 383 kgC km-2 yr-1 and 261 ± 56 kgN km-2 yr-1, respectively) than the other rivers of India (951 ± 508 kgC km-2 yr-1 and 120 ± 57 kgN km-2 yr-1, respectively). These findings stress that the export flux and yield of POC and PN from the Indian monsoonal rivers are primarily influenced by the interplay of hydrological, lithological, environmental, and climatic conditions within the catchment, rather than river size. Moreover, this study highlights the significant impact of incorporating POC data from medium-sized rivers worldwide, as it reveals that yield is independent of river size. This calls for a re-evaluation of global POC export fluxes, taking into account hydrological, lithological, environmental, and climatic factors.
Collapse
Affiliation(s)
- M S Krishna
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530017, India.
| | - M H K Prasad
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530017, India
| | - S A Naidu
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530017, India
| | - G Srikanth
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530017, India
| | - N P C Reddy
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530017, India
| | - N S Sarma
- Dept of PNCO, School of Chemistry, Andhra University, Visakhapatnam, 530017, India
| |
Collapse
|
3
|
Waturuocha UW, Krishna MS, Malhotra V, Dixit NM, Saini DK. A Low-Prevalence Single-Nucleotide Polymorphism in the Sensor Kinase PhoR in Mycobacterium tuberculosis Suppresses Its Autophosphatase Activity and Reduces Pathogenic Fitness: Implications in Evolutionary Selection. Front Microbiol 2021; 12:724482. [PMID: 34512602 PMCID: PMC8424205 DOI: 10.3389/fmicb.2021.724482] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 07/30/2021] [Indexed: 12/30/2022] Open
Abstract
The genome sequencing of Mycobacterium tuberculosis, the causative organism of tuberculosis, has significantly improved our understanding of the mechanisms that drive the establishment of infection and disease progression. Several clinical strains of M. tuberculosis exhibit single-nucleotide polymorphisms (SNPs), the implications of which are only beginning to be understood. Here, we examined the impact of a specific polymorphism in PhoR, the sensor kinase of the PhoPR two-component system. Biochemical analysis revealed reduced autophosphatase/ATPase activity, which led to enhanced downstream gene expression. We complemented M. tuberculosis H37Ra with the wild-type and mutant phoPR genes and characterized the strains in a cell line infection model. We provide an explanation for the low prevalence of the SNP in clinical strains (∼1%), as the mutation causes a survival disadvantage in the host cells. The study provides a rare example of selection of a signaling node under competing evolutionary forces, wherein a biochemically superior mutation aids bacterial adaptation within-host but has low fitness for infection and hence is not selected. Our study highlights the importance of accounting for such SNPs to test therapeutic and co-therapeutic methods to combat TB.
Collapse
Affiliation(s)
- Uchenna Watson Waturuocha
- Department of Studies in Zoology, University of Mysore, Mysore, India.,Department of Molecular Reproduction Development and Genetics, Indian Institute of Science, Bengaluru, India
| | - M S Krishna
- Department of Studies in Zoology, University of Mysore, Mysore, India
| | | | - Narendra M Dixit
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, India.,Center for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
| | - Deepak Kumar Saini
- Department of Molecular Reproduction Development and Genetics, Indian Institute of Science, Bengaluru, India.,Center for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
| |
Collapse
|
4
|
Tai Tay DJ, Song Y, Peng B, Toh TB, Hooi L, Kaixin Toh DF, Hong H, Tang SJ, Han J, Gan WL, Man Chan TH, Krishna MS, Patil KM, Maraswami M, Loh TP, Dan YY, Zhou L, Bonney GK, Kah-Hoe Chow P, Chen G, Kai-Hua Chow E, Le MT, Chen L. Targeting RNA Editing of Antizyme Inhibitor 1: a Potential Oligonucleotide-Based Antisense Therapy for Cancer. Mol Ther 2021; 29:3258-3273. [PMID: 33974998 PMCID: PMC8571177 DOI: 10.1016/j.ymthe.2021.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 03/29/2021] [Accepted: 05/05/2021] [Indexed: 11/26/2022] Open
Abstract
Dysregulated adenosine-to-inosine (A-to-I) RNA editing is implicated in various cancers. However, no available RNA editing inhibitors have so far been developed to inhibit cancer-associated RNA editing events. Here, we decipher the RNA secondary structure of antizyme inhibitor 1 (AZIN1), one of the best-studied A-to-I editing targets in cancer, by locating its editing site complementary sequence (ECS) at the 3′ end of exon 12. Chemically modified antisense oligonucleotides (ASOs) that target the editing region of AZIN1 caused a substantial exon 11 skipping, whereas ECS-targeting ASOs effectively abolished AZIN1 editing without affecting splicing and translation. We demonstrate that complete 2′-O-methyl (2′-O-Me) sugar ring modification in combination with partial phosphorothioate (PS) backbone modification may be an optimal chemistry for editing inhibition. ASO3.2, which targets the ECS, specifically inhibits cancer cell viability in vitro and tumor incidence and growth in xenograft models. Our results demonstrate that this AZIN1-targeting, ASO-based therapeutics may be applicable to a wide range of tumor types.
Collapse
Affiliation(s)
- Daryl Jin Tai Tay
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Yangyang Song
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Boya Peng
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600; Department of Biomedical Sciences, School of Veterinary Medicine and Life Sciences, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Tan Boon Toh
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; The N.1 Institute for Health (N.1), 28 Medical Dr, Singapore 117456
| | - Lissa Hooi
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - HuiQi Hong
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117593
| | - Sze Jing Tang
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Jian Han
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Wei Liang Gan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Tim Hon Man Chan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Manikantha Maraswami
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Teck Peng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Yock Young Dan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Division of Gastroenterology and Hepatology, National University Health System, Singapore 119228
| | - Lei Zhou
- Division of Gastroenterology and Hepatology, National University Health System, Singapore 119228
| | - Glenn Kunnath Bonney
- Division of Hepatobiliary and Liver Transplantation Surgery, National University Health System, Singapore 119228
| | - Pierce Kah-Hoe Chow
- Division of Surgical Oncology, National Cancer Centre Singapore, Singapore 169610; Department of Hepato-Pancreato-Biliary and Transplant Surgery, Singapore General Hospital, Singapore 169608; Duke-NUS Medical School, Singapore 169857
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Edward Kai-Hua Chow
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600; The N.1 Institute for Health (N.1), 28 Medical Dr, Singapore 117456
| | - Minh Tn Le
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600; Department of Biomedical Sciences, School of Veterinary Medicine and Life Sciences, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Leilei Chen
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, 4 Medical Drive, Singapore 117594.
| |
Collapse
|
5
|
Yang L, Toh DFK, Krishna MS, Zhong Z, Liu Y, Wang S, Gong Y, Chen G. Tertiary Base Triple Formation in the SRV-1 Frameshifting Pseudoknot Stabilizes Secondary Structure Components. Biochemistry 2020; 59:4429-4438. [PMID: 33166472 DOI: 10.1021/acs.biochem.0c00611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Minor-groove base triples formed between stem 1 and loop 2 of the simian retrovirus type 1 (SRV-1) mRNA frameshifting pseudoknot are essential in stimulating -1 ribosomal frameshifting. How tertiary base triple formation affects the local stabilities of secondary structures (stem 1 and stem 2) and thus ribosomal frameshifting efficiency is not well understood. We made a short peptide nucleic acid (PNA) that is expected to invade stem 1 of the SRV-1 pseudoknot by PNA-RNA duplex formation to mimic the stem 1 unwinding process by a translating ribosome. In addition, we used a PNA for invading stem 2 in the SRV-1 pseudoknot. Our nondenaturing polyacrylamide gel electrophoresis data for the binding of PNA to the SRV-1 pseudoknot and mutants reveal that mutations in loop 2 disrupting base triple formation between loop 2 and stem 1 in the SRV-1 pseudoknot result in enhanced invasion by both PNAs. Our data suggest that tertiary stem 1-loop 2 base triple interactions in the SRV-1 pseudoknot can stabilize both of the secondary structural components, stem 1 and stem 2. Stem 2 stability is thus coupled to the structural stability of stem 1-loop 2 base triples, mediated through a long-range effect. The apparent dissociation constants of both PNAs are positively correlated with the pseudoknot mechanical stabilities and frameshifting efficiencies. The relatively simple PNA local invasion experiment may be used to characterize the energetic contribution of tertiary interactions and ligand binding in many other RNA and DNA structures.
Collapse
Affiliation(s)
- Lixia Yang
- School of Life Science and Technology, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China.,School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), No. 2001 Longxiang Boulevard, Longgang District, Shenzhen, Guangdong 518172, P. R. China.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhensheng Zhong
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, P. R. China
| | - Yiyao Liu
- School of Life Science and Technology, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China
| | - Shaomeng Wang
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China
| | - Yubin Gong
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu, Sichuan 610054, P. R. China
| | - Gang Chen
- School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), No. 2001 Longxiang Boulevard, Longgang District, Shenzhen, Guangdong 518172, P. R. China.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| |
Collapse
|
6
|
Sarma VVSS, Krishna MS, Srinivas TNR. Sources of organic matter and tracing of nutrient pollution in the coastal Bay of Bengal. Mar Pollut Bull 2020; 159:111477. [PMID: 32750595 DOI: 10.1016/j.marpolbul.2020.111477] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 07/10/2020] [Accepted: 07/11/2020] [Indexed: 05/06/2023]
Abstract
Stable isotopic composition of carbon (δ13CPOM) and nitrogen (δ15NPOM) in the particulate organic matter (POM) is used to identify sources of organic carbon and nutrients using monthly time-series observation in the coastal Bay of Bengal (BoB). The hydrographic structure indicates that the coastal BoB is influenced by coastal upwelling during March-May, advection of peninsular river discharge during June to September and glacial (Ganges) river discharge during October to December due to reversing of East India Coastal Currents (EICC). C/N ratios in POM were mostly higher values than Redfield ratio in the study region indicating possible contribution of terrestrial origin. Enriched δ13CPOM were found during March-May associated with coastal upwelling indicating major contribution of POM from the in situ production while lower values were noticed during June to September followed by October to December indicating influence of terrestrial sources. δ15NPOM displayed strong inverse relation with salinity and linear relation with Chl-a suggesting that anthropogenic nutrients from the land increased coastal phytoplankton biomass. δ15NPOM linearly decreased with increase in distance from the coast and reached to the typical offshore value of 6-6.5‰ indicating that terrestrial nutrients influence was spread up to a distance of 15 to 20 km from the coast in the study region. Our study suggested that coastal waters are influenced by terrestrial/anthropogenic nutrients and its impact can be noticed up to 15 to 20 km from the coast and its impact on Biodiversity Beyond National Jurisdiction may be negligible than hitherto hypothesized.
Collapse
Affiliation(s)
- V V S S Sarma
- CSIR-National Institute of Oceanography, Regional Centre, 176 Lawsons Bay Colony, Visakhapatnam 530017, India; Academy of Scientific and Innovative Research (AcSIR), Dona Paula, Goa, India.
| | - M S Krishna
- CSIR-National Institute of Oceanography, Regional Centre, 176 Lawsons Bay Colony, Visakhapatnam 530017, India
| | - T N R Srinivas
- CSIR-National Institute of Oceanography, Regional Centre, 176 Lawsons Bay Colony, Visakhapatnam 530017, India
| |
Collapse
|
7
|
Krishna MS, Wang Z, Zheng L, Bowry J, Ong AAL, Mu Y, Prabakaran M, Chen G. Incorporating G-C Pair-Recognizing Guanidinium into PNAs for Sequence and Structure Specific Recognition of dsRNAs over dsDNAs and ssRNAs. Biochemistry 2019; 58:3777-3788. [PMID: 31424191 DOI: 10.1021/acs.biochem.9b00608] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Recognition of RNAs under physiological conditions is important for the development of chemical probes and therapeutic ligands. Nucleobase-modified dsRNA-binding PNAs (dbPNAs) are promising for the recognition of dsRNAs in a sequence and structure specific manner under near-physiological conditions. Guanidinium is often present in proteins and small molecules for the recognition of G bases in nucleic acids, in cell-penetrating carriers, and in bioactive drug molecules, which might be due to the fact that guanidinium is amphiphilic and has unique hydrogen bonding and stacking properties. We hypothesized that a simple guanidinium moiety can be directly incorporated into PNAs to facilitate enhanced molecular recognition of G-C pairs in dsRNAs and improved bioactivity. We grafted a guanidinium moiety directly into a PNA monomer (designated as R) using a two-carbon linker as guided by computational modeling studies. The synthetic scheme of the PNA R monomer is relatively simple compared to that of the previously reported L monomer. We incorporated the R residue into various dbPNAs for binding studies. dbPNAs incorporated with R residues are excellent in sequence specifically recognizing G-C pairs in dsRNAs over dsDNA and ssRNAs. We demonstrated that the R residue is compatible with unmodified T and C and previously developed modified L and Q residues in dbPNAs for targeting model dsRNAs, the influenza A viral panhandle duplex structure, and the HIV-1 frameshift site RNA hairpin. Furthermore, R residues enhance the cellular uptake of PNAs.
Collapse
Affiliation(s)
- Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhenzhang Wang
- Temasek Life Science Laboratory, 1 Research Link, National University of Singapore , Singapore 117604
| | - Liangzhen Zheng
- School of Biological Sciences , Nanyang Technological University , Singapore 637551
| | - Jogesh Bowry
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371.,Department of Chemistry , University of Southampton , Southampton SO17 1BJ , U.K
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Yuguang Mu
- School of Biological Sciences , Nanyang Technological University , Singapore 637551
| | - Mookkan Prabakaran
- Temasek Life Science Laboratory, 1 Research Link, National University of Singapore , Singapore 117604
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| |
Collapse
|
8
|
Ong AAL, Toh DFK, Krishna MS, Patil KM, Okamura K, Chen G. Incorporating 2-Thiouracil into Short Double-Stranded RNA-Binding Peptide Nucleic Acids for Enhanced Recognition of A-U Pairs and for Targeting a MicroRNA Hairpin Precursor. Biochemistry 2019; 58:3444-3453. [PMID: 31318532 DOI: 10.1021/acs.biochem.9b00521] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chemically modified short peptide nucleic acids (PNAs) recognize RNA duplexes under near physiological conditions by major-groove PNA·RNA-RNA triplex formation and show great promise for the development of RNA-targeting probes and therapeutics. Thymine (T) and uracil (U) are often incorporated into PNAs to recognize A-U pairs through major-groove T·A-U and U·A-U base triple formation. Incorporation of a modified nucleobase, 2-thiouracil (s2U), into triplex-forming oligonucleotides stabilizes both DNA and RNA triplexes. Thiolation of uracil causes a decrease in the dehydration energy penalty for triplex formation as well as a decrease in the pKa of the N3 atom, which may result in improved hydrogen bonding in addition to enhanced base stacking interactions, similar to the previously reported thiolation effect of pseudoisocytosine (J to L substitution). Here, we incorporated s2U into short PNAs, followed by binding studies of a series of s2U-modified PNAs. We demonstrated by nondenaturing polyacrylamide gel electrophoresis and thermal melting experiments that s2U and L incorporated into dsRNA-binding PNAs (dbPNAs) enhance the recognition of A-U and G-C pairs, respectively, in RNA duplexes in a position-independent manner, with no appreciable binding to the DNA duplex. Combining s2U and L modifications in dbPNAs facilitates enhanced recognition of dsRNAs and maintains selective binding to dsRNAs over ssRNAs. We further demonstrated through a cell-free assay the application of the s2U- and L-modified dbPNAs (8-mer, with a molecular mass of ∼2.3 kDa) in the inhibition of the pre-microRNA-198 maturation in a substrate-specific manner. Thus, s2U-modified dbPNAs may be generally useful for the enhanced and selective recognition of RNA duplexes and for the regulation of RNA functions.
Collapse
Affiliation(s)
- Alan Ann Lerk Ong
- NTU Institute for Health Technologies (HeathTech NTU), Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , Singapore 637553.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Katsutomo Okamura
- Division of Biological Sciences , Nara Institute of Science and Technology , 8916-5 Takayama , Ikoma , Nara 630-0192 , Japan
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| |
Collapse
|
9
|
Krishna MS, Toh DFK, Meng Z, Ong AAL, Wang Z, Lu Y, Xia K, Prabakaran M, Chen G. Sequence- And Structure-Specific Probing of RNAs by Short Nucleobase-Modified dsRNA-Binding PNAs Incorporating a Fluorescent Light-up Uracil Analog. Anal Chem 2019; 91:5331-5338. [PMID: 30873827 DOI: 10.1021/acs.analchem.9b00280] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
RNAs are emerging as important biomarkers and therapeutic targets. The strategy of directly targeting double-stranded RNA (dsRNA) by triplex-formation is relatively underexplored mainly due to the weak binding at physiological conditions for the traditional triplex-forming oligonucleotides (TFOs). Compared to DNA and RNA, peptide nucleic acids (PNAs) are chemically stable and have a neutral peptide-like backbone, and thus, they show significantly enhanced binding to natural nucleic acids. We have successfully developed nucleobase-modified dsRNA-binding PNAs (dbPNAs) to facilitate structure-specific and selective recognition of dsRNA over single-stranded RNA (ssRNA) and dsDNA regions at near-physiological conditions. The triplex formation strategy facilitates the targeting of not only the sequence but also the secondary structure of RNA. Here, we report the development of novel dbPNA-based fluorescent light-up probes through the incorporation of A-U pair-recognizing 5-benzothiophene uracil (btU). The incorporation of btU into dbPNAs does not affect the binding affinity toward dsRNAs significantly, in most cases, as evidenced by our nondenaturing gel shift assay data. The blue fluorescence emission intensity of btU-modified dbPNAs is sequence- and structure-specifically enhanced by dsRNAs, including the influenza viral RNA panhandle duplex and HIV-1-1 ribosomal frameshift-inducing RNA hairpin, but not ssRNAs or DNAs, at 200 mM NaCl, pH 7.5. Thus, dbPNAs incorporating btU-modified and other further modified fluorescent nucleobases will be useful biochemical tools for probing and detecting RNA structures, interactions, and functions.
Collapse
Affiliation(s)
- Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Zhenyu Meng
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Zhenzhang Wang
- Temasek Life Science Laboratory , 1 Research Link, National University of Singapore , 117604 , Singapore
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Kelin Xia
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Mookkan Prabakaran
- Temasek Life Science Laboratory , 1 Research Link, National University of Singapore , 117604 , Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| |
Collapse
|
10
|
Ong AAL, Toh DFK, Patil KM, Meng Z, Yuan Z, Krishna MS, Devi G, Haruehanroengra P, Lu Y, Xia K, Okamura K, Sheng J, Chen G. General Recognition of U-G, U-A, and C-G Pairs by Double-Stranded RNA-Binding PNAs Incorporated with an Artificial Nucleobase. Biochemistry 2019; 58:1319-1331. [PMID: 30775913 DOI: 10.1021/acs.biochem.8b01313] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Chemically modified peptide nucleic acids (PNAs) show great promise in the recognition of RNA duplexes by major-groove PNA·RNA-RNA triplex formation. Triplex formation is favored for RNA duplexes with a purine tract within one of the RNA duplex strands, and is severely destabilized if the purine tract is interrupted by pyrimidine residues. Here, we report the synthesis of a PNA monomer incorporated with an artificial nucleobase S, followed by the binding studies of a series of S-modified PNAs. Our data suggest that an S residue incorporated into short 8-mer dsRNA-binding PNAs (dbPNAs) can recognize internal Watson-Crick C-G and U-A, and wobble U-G base pairs (but not G-C, A-U, and G-U pairs) in RNA duplexes. The short S-modified PNAs show no appreciable binding to DNA duplexes or single-stranded RNAs. Interestingly, replacement of the C residue in an S·C-G triple with a 5-methyl C results in the disruption of the triplex, probably due to a steric clash between S and 5-methyl C. Previously reported PNA E base shows recognition of U-A and A-U pairs, but not a U-G pair. Thus, S-modified dbPNAs may be uniquely useful for the general recognition of RNA U-G, U-A, and C-G pairs. Shortening the succinyl linker of our PNA S monomer by one carbon atom to have a malonyl linker causes a severe destabilization of triplex formation. Our experimental and modeling data indicate that part of the succinyl moiety in a PNA S monomer may serve to expand the S base forming stacking interactions with adjacent PNA bases.
Collapse
Affiliation(s)
- Alan Ann Lerk Ong
- NTU Institute for Health Technologies (HeathTech NTU), Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , Singapore 637553.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhenyu Meng
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhen Yuan
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Gitali Devi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Phensinee Haruehanroengra
- Department of Chemistry and The RNA Institute , University at Albany, State University of New York , 1400 Washington Avenue , Albany , New York 12222 , United States
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kelin Xia
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Katsutomo Okamura
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore , Singapore , 117604.,School of Biological Sciences , Nanyang Technological University , 60 Nanyang Drive , Singapore , 639798
| | - Jia Sheng
- Department of Chemistry and The RNA Institute , University at Albany, State University of New York , 1400 Washington Avenue , Albany , New York 12222 , United States
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| |
Collapse
|
11
|
Kesy J, Patil KM, Kumar SR, Shu Z, Yong HY, Zimmermann L, Ong AAL, Toh DFK, Krishna MS, Yang L, Decout JL, Luo D, Prabakaran M, Chen G, Kierzek E. A Short Chemically Modified dsRNA-Binding PNA (dbPNA) Inhibits Influenza Viral Replication by Targeting Viral RNA Panhandle Structure. Bioconjug Chem 2019; 30:931-943. [PMID: 30721034 DOI: 10.1021/acs.bioconjchem.9b00039] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
RNAs play critical roles in diverse catalytic and regulatory biological processes and are emerging as important disease biomarkers and therapeutic targets. Thus, developing chemical compounds for targeting any desired RNA structures has great potential in biomedical applications. The viral and cellular RNA sequence and structure databases lay the groundwork for developing RNA-binding chemical ligands through the recognition of both RNA sequence and RNA structure. Influenza A virion consists of eight segments of negative-strand viral RNA (vRNA), all of which contain a highly conserved panhandle duplex structure formed between the first 13 nucleotides at the 5' end and the last 12 nucleotides at the 3' end. Here, we report our binding and cell culture anti-influenza assays of a short 10-mer chemically modified double-stranded RNA (dsRNA)-binding peptide nucleic acid (PNA) designed to bind to the panhandle duplex structure through novel major-groove PNA·RNA2 triplex formation. We demonstrated that incorporation of chemically modified PNA residues thio-pseudoisocytosine (L) and guanidine-modified 5-methyl cytosine (Q) previously developed by us facilitates the sequence-specific recognition of Watson-Crick G-C and C-G pairs, respectively, at physiologically relevant conditions. Significantly, the chemically modified dsRNA-binding PNA (dbPNA) shows selective binding to the dsRNA region in panhandle structure over a single-stranded RNA (ssRNA) and a dsDNA containing the same sequence. The panhandle structure is not accessible to traditional antisense DNA or RNA with a similar length. Conjugation of the dbPNA with an aminosugar neamine enhances the cellular uptake. We observed that 2-5 μM dbPNA-neamine conjugate results in a significant reduction of viral replication. In addition, the 10-mer dbPNA inhibits innate immune receptor RIG-I binding to panhandle structure and thus RIG-I ATPase activity. These findings would provide the foundation for developing novel dbPNAs for the detection of influenza viral RNAs and therapeutics with optimal antiviral and immunomodulatory activities.
Collapse
Affiliation(s)
- Julita Kesy
- Institute of Bioorganic Chemistry, Polish Academy of Sciences , Noskowskiego 12/14 , 61-704 Poznan , Poland
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | | | - Zhiyu Shu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Hui Yee Yong
- Lee Kong Chian School of Medicine , Nanyang Technological University , EMB 03-07, 59 Nanyang Drive , 636921 , Singapore.,NTU Institute of Structural Biology , Nanyang Technological University , EMB 06-01, 59 Nanyang Drive , 636921 , Singapore.,School of Biological Sciences , Nanyang Technological University , 60 Nanyang Drive , 636921 , Singapore
| | - Louis Zimmermann
- Département de Pharmacochimie Moléculaire , University Grenoble Alpes, CNRS, ICMG FR 2607, UMR 5063 , 470 Rue de la Chimie , F-38041 Grenoble , France
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Lixia Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Jean-Luc Decout
- Département de Pharmacochimie Moléculaire , University Grenoble Alpes, CNRS, ICMG FR 2607, UMR 5063 , 470 Rue de la Chimie , F-38041 Grenoble , France
| | - Dahai Luo
- Lee Kong Chian School of Medicine , Nanyang Technological University , EMB 03-07, 59 Nanyang Drive , 636921 , Singapore.,NTU Institute of Structural Biology , Nanyang Technological University , EMB 06-01, 59 Nanyang Drive , 636921 , Singapore
| | - Mookkan Prabakaran
- Temasek Life Science Laboratory, 1 Research Link , National University of Singapore , 117604 , Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Elzbieta Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences , Noskowskiego 12/14 , 61-704 Poznan , Poland
| |
Collapse
|
12
|
Patil KM, Toh DFK, Yuan Z, Meng Z, Shu Z, Zhang H, Ong A, Krishna MS, Lu L, Lu Y, Chen G. Incorporating uracil and 5-halouracils into short peptide nucleic acids for enhanced recognition of A-U pairs in dsRNAs. Nucleic Acids Res 2018; 46:7506-7521. [PMID: 30011039 PMCID: PMC6125629 DOI: 10.1093/nar/gky631] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 06/09/2018] [Accepted: 07/03/2018] [Indexed: 01/16/2023] Open
Abstract
Double-stranded RNA (dsRNA) structures form triplexes and RNA-protein complexes through binding to single-stranded RNA (ssRNA) regions and proteins, respectively, for diverse biological functions. Hence, targeting dsRNAs through major-groove triplex formation is a promising strategy for the development of chemical probes and potential therapeutics. Short (e.g., 6-10 mer) chemically-modified Peptide Nucleic Acids (PNAs) have been developed that bind to dsRNAs sequence specifically at physiological conditions. For example, a PNA incorporating a modified base thio-pseudoisocytosine (L) has an enhanced recognition of a G-C pair in an RNA duplex through major-groove L·G-C base triple formation at physiological pH, with reduced pH dependence as observed for C+·G-C base triple formation. Currently, an unmodified T base is often incorporated into PNAs to recognize a Watson-Crick A-U pair through major-groove T·A-U base triple formation. A substitution of the 5-methyl group in T by hydrogen and halogen atoms (F, Cl, Br, and I) causes a decrease of the pKa of N3 nitrogen atom, which may result in improved hydrogen bonding in addition to enhanced base stacking interactions. Here, we synthesized a series of PNAs incorporating uracil and halouracils, followed by binding studies by non-denaturing polyacrylamide gel electrophoresis, circular dichroism, and thermal melting. Our results suggest that replacing T with uracil and halouracils may enhance the recognition of an A-U pair by PNA·RNA2 triplex formation in a sequence-dependent manner, underscoring the importance of local stacking interactions. Incorporating bromouracils and chlorouracils into a PNA results in a significantly reduced pH dependence of triplex formation even for PNAs containing C bases, likely due to an upshift of the apparent pKa of N3 atoms of C bases. Thus, halogenation and other chemical modifications may be utilized to enhance hydrogen bonding of the adjacent base triples and thus triplex formation. Furthermore, our experimental and computational modelling data suggest that PNA·RNA2 triplexes may be stabilized by incorporating a BrUL step but not an LBrU step, in dsRNA-binding PNAs.
Collapse
Affiliation(s)
- Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhen Yuan
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhenyu Meng
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhiyu Shu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Haiping Zhang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| |
Collapse
|
13
|
Puah RY, Jia H, Maraswami M, Toh DFK, Ero R, Yang L, Patil KM, Ong AAL, Krishna MS, Sun R, Tong C, Huang M, Chen X, Loh TP, Gao YG, Liu DX, Chen G. Selective Binding to mRNA Duplex Regions by Chemically Modified Peptide Nucleic Acids Stimulates Ribosomal Frameshifting. Biochemistry 2017; 57:149-159. [PMID: 29116759 DOI: 10.1021/acs.biochem.7b00744] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Minus-one programmed ribosomal frameshifting (-1 PRF) allows the precise maintenance of the ratio between viral proteins and is involved in the regulation of the half-lives of cellular mRNAs. Minus-one ribosomal frameshifting is activated by several stimulatory elements such as a heptameric slippery sequence (X XXY YYZ) and an mRNA secondary structure (hairpin or pseudoknot) that is positioned 2-8 nucleotides downstream from the slippery site. Upon -1 RF, the ribosomal reading frame is shifted from the normal zero frame to the -1 frame with the heptameric slippery sequence decoded as XXX YYY Z instead of X XXY YYZ. Our research group has developed chemically modified peptide nucleic acid (PNA) L and Q monomers to recognize G-C and C-G Watson-Crick base pairs, respectively, through major-groove parallel PNA·RNA-RNA triplex formation. L- and Q-incorporated PNAs show selective binding to double-stranded RNAs (dsRNAs) over single-stranded RNAs (ssRNAs). The sequence specificity and structural selectivity of L- and Q-modified PNAs may allow the precise targeting of desired viral and cellular RNA structures, and thus may serve as valuable biological tools for mechanistic studies and potential therapeutics for fighting diseases. Here, for the first time, we demonstrate by cell-free in vitro translation assays using rabbit reticulocyte lysate that the dsRNA-specific chemically modified PNAs targeting model mRNA hairpins stimulate -1 RF (from 2% to 32%). An unmodified control PNA, however, shows nonspecific inhibition of translation. Our results suggest that the modified dsRNA-binding PNAs may be advantageous for targeting structured RNAs.
Collapse
Affiliation(s)
| | | | | | | | - Rya Ero
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551
| | | | | | | | | | | | | | - Mei Huang
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551
| | | | | | - Yong-Gui Gao
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551
| | - Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551.,Guangdong Province Key Laboratory Microbial Signals & Disease Co, and Integrative Microbiology Research Centre, South China Agricultural University , Guangzhou 510642, Guangdong, People's Republic of China
| | | |
Collapse
|
14
|
Suneel V, Vethamony P, Naik BG, Krishna MS, Jadhav L. Identifying the source of tar balls deposited along the beaches of Goa in 2013 and comparing with historical data collected along the West Coast of India. Sci Total Environ 2015; 527-528:313-321. [PMID: 25965045 DOI: 10.1016/j.scitotenv.2015.04.102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/25/2015] [Accepted: 04/27/2015] [Indexed: 06/04/2023]
Abstract
Deposition of oil residues, also known as tar balls, is a seasonal phenomenon, and it occurs only in the southwest monsoon season along the west coast of India. This has become a serious environmental issue, as Goa is a global tourist destination. The present work aims at identifying the source oil of the tar balls that consistently depositing along the Goa coast using multi-marker fingerprint technique. In this context, the tar ball samples collected in May 2013 from 9 beaches of Goa coast and crude oils from different oil fields and grounded ship were subject to multi-marker analyses such as n-alkanes, pentacyclic terpanes, regular steranes, compound specific isotope analysis (CSIA) and principle component analysis (PCA). The n-alkane weathering index shows that samples have been weathered to various degrees, and the status of weathering is moderate. Since the international tanker route passes closer to the west coast of India (WCI), it is generally presumed that tanker wash is the source of the tar balls. We found that 2010/2011 tar balls are as tanker wash, but the present study demonstrates that the Bombay High (BH) oil fields can also contribute to oil contamination (tar balls) along ≈ 650 km stretch of the WCI, running from Gujarat in the north to Goa in the south. The simulated trajectories show that all the particles released in April traveled in the southeast direction, and by May, they reached the Goa coast with the influence of circulation of Indian monsoon system.
Collapse
Affiliation(s)
- V Suneel
- CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India.
| | - P Vethamony
- CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India.
| | - B G Naik
- CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India.
| | - M S Krishna
- CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530 017, India.
| | | |
Collapse
|
15
|
Verma A, Krishna MS. To report a case of unilateral proliferative retinopathy following noncerebral malaria with Plasmodium falciparum in Southern India. Indian J Ophthalmol 2015; 63:63-6. [PMID: 25686067 PMCID: PMC4363962 DOI: 10.4103/0301-4738.151475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The retinopathy in association with malaria fever described so far includes retinal hemorrhages, vessel changes, retinal discoloration/whitening and papilledema. Malaria retinopathy has been mostly described in severe cases, associated with Plasmodium falciparum, correlating the patho-physiology of retinal and cerebral manifestations. We report an unusual case of proliferative retinopathy as a manifestation of malaria fever, caused by P. falciparum with no cerebral involvement. The patient had features of unilateral retinal vascular occlusion with proliferative changes and vitreous hemorrhage. To the best of our knowledge, such a case has never been reported so far in the literature. This report highlights the possible occurrence of severe proliferative changes associated with malaria fever, which if diagnosed early can prevent possible blindness.
Collapse
Affiliation(s)
- Aditya Verma
- Sri Bhagwan Mahavir Vitreoretinal Services, Medical Research Foundation, Sankara Nethralaya, Nungambakkam, Chennai - 600 006, Tamil Nadu, India
| | | |
Collapse
|
16
|
Moorthy JN, Natarajan P, Krishna MS, Nagarajaiah H, Venugopalan P. Isomorphous three-component crystals (pseudopolymorphs of binary cocrystals) based on lattice inclusion of guests with a sterically-rigidified tetraarylpyrene host. CrystEngComm 2015. [DOI: 10.1039/c5ce00243e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
17
|
Rezaei A, Krishna MS, Santhosh H, Jayaramu S. Preliminary studies: the effect of temperature on the accessory gland in Drosophila melanogaster. Egyptian Academic Journal of Biological Sciences A, Entomology 2012. [DOI: 10.21608/eajbsa.2012.14910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
|
18
|
Hegde SN, Chethan BK, Krishna MS. Mating success of males with and without wing patch in Drosophila biarmipes. Indian J Exp Biol 2005; 43:902-9. [PMID: 16235725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Some males of D. biarmipes--synonym of D. rajasekari and D. raychaudhuri have a black patch on the wing. The patch extends from the apical margin of wing to the third longitudinal vein. Field and laboratory studies have been carried out in D. biarmipes to study role of male's wing patch in mating success. The field study shows that nature favors D. biarmipes males with patch. Although males without patch mated, males with patch have higher mating success suggesting the role of wing patch during courtship. Further, among mating males, males with patch had longer wings than males without patch. During courtship, males with patch oriented and mated faster; performed courtship acts such as tapping, scissoring, vibration, licking and twist dance more times than males without patch in both competitive and non-competitive situations. The results indicate that there is a casual relationship between the presence of wing patch, mating speed and success. Also there is a correlation between presence of wing patch, size of the flies and mating success.
Collapse
Affiliation(s)
- S N Hegde
- Drosophila Stock Center, Department of Studies in Zoology, University of Mysore, Manasagangothri, Mysore 570 006, India.
| | | | | |
Collapse
|
19
|
Hegde SN, Naseerulla MK, Krishna MS. Variability of morphological traits in Drosophila bipectinata complex. Indian J Exp Biol 2000; 38:797-806. [PMID: 12557913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Phenotypic or morphological differences among different populations and sexual dimorphism in certain metric traits were analysed in D. bipectinata complex. It was noticed that different populations of D. bipectinata species group harbour large amount of variation for these characters. In all the populations, morphometric characters such as lengths of femur, tibia and wing length, wing width, number of sternopleural bristles and bristles on epandrium varied significantly among populations. The study indicates that the morphological variations are due to the interplay of genetic and environmental endowments. Further, females had significantly larger values, for lengths of femur, tibia and wing length, wing width and sternopleural bristles.
Collapse
Affiliation(s)
- S N Hegde
- Drosophila Stock Centre, Department of Studies in Zoology, University of Mysore, Manasagangothri, Mysore 570 006, India
| | | | | |
Collapse
|
20
|
Hegde SN, Krishna MS. Bottleneck effect on intra- and interspecific competition in Drosophila malerkotliana. Indian J Exp Biol 1999; 37:359-64. [PMID: 10641172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Intra and interspecific competition experiments involving control and bottleneck lines of monomorphic and polymorphic populations of D.malerkotliana with D.nasuta nasuta have been carried out. Productivity and population size were evaluated in these lines. The results show that control line had higher relative fitness and adaptedness (productivity and population size) under both intra and interspecific competition than their respective bottleneck lines and D.nasuta nasuta. This indicates that bottlenecks have an effect on competition in D.malerkotliana. The consequence of such competition studies using control and bottleneck lines of D.malerkotliana and D.nasuta nasuta is discussed.
Collapse
Affiliation(s)
- S N Hegde
- Drosophila Stock Centre, Department of Studies in Zoology, University of Mysore, Manasagangothri, India
| | | |
Collapse
|
21
|
Krishna MS, Hegde SN. Body size, mating success and advantage of large flies in Drosophila bipectinata species complex. Indian J Exp Biol 1997; 35:1341-7. [PMID: 9567772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mating success of large and small flies of Drosophila malerkotliana and D. bipectinata was studied using multiple, male and female choice methods. In multiple choice method the large male mated with large female and small male paired with small female. In female choice method, large male was successful in mating with female irrespective of its size while in male choice method, preferential mating occurred between large male and large female as well as small male and small female. The consequence of such non-random mating in the presence of male rivarly and preferential mating has been discussed.
Collapse
Affiliation(s)
- M S Krishna
- Department of Studies in Zoology, University of Mysore Manasagangotri, India
| | | |
Collapse
|
22
|
Abstract
The relationships between wing size, locomotor activity, mating latency, courtship pattern and mating success (total number of pairs mated in a given time unit) were studied in pairs of Drosophila malerkotlianaMating latency was negatively correlated with wing length and with locomotor activity while wing length and locomotor activity were positively related. In trios of a female and a long-winged and a short-winged male, long-winged males mated more successfully than short-winged males. In trios of a male and a long-winged and a short-winged female, long-winged males mated with long-winged females, and short-winged males with short-winged females. In addition, in pairs of long-winged/short-winged flies, long-winged flies courted and mated more successfully than short-winged flies.
Collapse
Affiliation(s)
- SN Hegde
- Department of Studies in Zoology, University of Mysore
| | | |
Collapse
|
23
|
Hegde SN, Krishna MS. Effect of bottlenecks on incipient sexual isolation, mating activity and fertility in Drosophila malerkotliana. Indian J Exp Biol 1996; 34:440-3. [PMID: 9063077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Effect of bottleneck sizes, on sexual isolation, mating speed and fertility were studied in D. malerkotliana established from natural population. After 10 generations of laboratory breeding, flies showed incipient sexual isolation between control line and some bottleneck lines and also between bottleneck lines. These findings do not fully agree with the general assumption that the establishment of bottlenecks accelerates speciation. The courtship latency and mating speed increases with increasing size of bottlenecks whereas copulation duration and fertility decreases with increasing bottleneck size. There was no sign of rebounding in fitness with in 10 generations as observed by Bryant et al. in house flies.
Collapse
Affiliation(s)
- S N Hegde
- Department of Studies in Zoology, University of Mysore, India
| | | |
Collapse
|