Scholastic record: (https://scholar.google.co.in/citations?user=fef1gNUAAAAJ&hl=en)
Fellowships and Awards
Genomic Instability and Diseases
Replication of DNA strands during each cell division is a prerequisite and critical for proper function of any genome. It is critical not only because of the necessity to duplicate the genetic content, but also because faulty DNA synthesis renders spontaneous mutation, genome rearrangement, and breaks in DNA; and these are the ingredients of genomic instability. Genomic instability is directly associated with cell death, tumorogenesis and development of an array of complex diseases in humans; also virulence and multidrug resistance in pathogens. DNA polymerases (Pol) are the enzymes required for DNA synthesis virtually in all DNA transaction pathways; and malfunction or absence of these has been shown to be associated with diseases in humans. Therefore, we are accentuating to analyze functions of eukaryotic pols in following areas.
I) Genetic and biochemical studies in S. cerevisiae have indicated that the highly accurate and processive genomic DNA replication is carried out by the coordinated action of Polα-primase, Polδ and Polε. A number of mutants of Pol3 (catalytic subunit of Polδ) and Pol2 (catalytic subunit of Polε) causing mutagenesis have been genetically characterized; however, the biochemical basis and mechanism have not been yet investigated. In depth analysis of such mutants will unravel the mechanism and novel factors involved in mutagenesis in yeast and carcinogenesis in humans; and results obtained will be a basis to identify possible target molecules (/sites) for cancer therapy.
II) DNA replication does not proceed smoothly; as it encounters both DNA lesions and non-B form of DNA structures that must be by-passed to prevent collapsing of replication fork. Discoveries and subsequent studies on DNA pols which can replicate past an array of DNA damages with a very high degree of specificity in yeast and human have broadened our understandings on the mechanism of replication of damaged DNA (Trans-lesion DNA synthesis, TLS). However, these groups of pols synthesize undamaged DNA with low fidelity and efficiency; and thereby, often generate mutations. How does a cell manage to select the right polymerase for a specific function?
III) Candida albicans, an opportunistic pathogen, which can asymptomatically colonizes humans can cause severe infection in immunocompromised people or when the microbiome is imbalanced. Available evidences suggest that genomic instability in the form of mutations and chromosomal aberrations is a common occurrence in pathogenic and drug resistant clinical isolates of C. albicans, and is believed to be one of the critical determinants of its virulence. We hypothesize that mutagenesis due to replication defects not only it will adopt Candida albicans to survive against the odds of host defense mechanism but also mutations in certain genes would activate pathways of morphological transition and multidrug resistance. Thus we are engaged in characterizing DNA polymerases from C. albicans to decipher its role in DNA replication, mutagenesis and its association with morphogenesis and multidrug resistance. We are also exploring the role of human microbiota in onset of oncogenesis and cancer proliferation. Recently, we have shown that PCNA, the sliding clamp of DNA replication is functionally different from S. cerevisiae which can be effectively targeted against candidasis (Manohar et. al., BMC-Microbiology, 2015). Our studies on Pol eta (Rad30), a Y-family DNA polymerase that promotes efficient bypass of UV-induced cyclobutane pyrimidine dimers and cisplatin adducts, from C. albicans (Satpati et al., 2017, Manohar et al., 2018) revealed that the roles of CaPolh in genome stability, genotoxins induced filamentation and azole drug tolerance are due to its TLS activities; whereas its TLS independent functions play a pivotal role in serum induced morphogenesis and amphotericin B resistance. Polh deficient C. albicans did not exhibit any hyphal development in the presence of genotoxins like UV and cisplatin, and non-genotoxic serum. Further, we are extending our study to compare the fate of Poleta-proficient and deficient strains of C. albicans in macrophage invasion and virulence in various genetic backgrounds of mice models to explore the strain as a potential live attenuated fungal vaccine .
Peer reviewed publications:
Prashant Khandagale (DBT -JRF) : DNA Replication in human
Shraddheya Kumar Patel (ILS -JRF): Deciphering role of DNA polymerase delta in C. albicans pathogenesis
Premlata Kumari (Inspire -JRF): Deciphering role of transcription factors in genotoxins induced C. albicans morphogenesis
Satya Ranjan Sahu (CSIR-JRF): TLS-mutasome complex and candidiasis
Bhabasha Gyanadeep (UGC-JRF): Nucleotide metabolism in Fungi
Jugal Kishore Sahu (CSIR-JRF): Human DNA polymerase theta
Doureiradju Peroumal, Ph. D. (DBT Project- RA): Virulence and pathogenicity of C. albicans
Sitendra Prasad Panda
Kodavati Manohar, Ph. D. (Graduated from the Laboratory in the year 2018)Ph. D. Thesis “Characterization of DNA polymerase eta ( (Polη/Rad30) from pathogenic yeast Candida albicans: Role in genome stability, morphogenesis and multidrug resistance”*
(* Currently Pursuing Post-doctoral training at University of Nebraska, USA)
Amrita Dalei (Lab. Technician – 2013-2018)
Shreenath Nayak, Ph.D. (DBT-RA; from the year 2013-2016)
Jawed Alam, Ph.D. (CSIR-RA)
Mousumi Sajjan (Summer project 2018,OUAT, BBSR)
Riya Gupta (IAS Fellow 2017, )
Ravi Kumar (IAS Fellow 2016, NIT, Durgapur)
M. Suresh (IAS Fellow 2015)
1. “Understanding the role of DNA polymerase eta dependent trans-lesion DNA synthesis in pathogenicity of Candida albicans”. Funded by DBT (2116-2019)
2. “Deciphering the role of DNA polymerase delta dependent mutagenesis in morphogenesis, multidrug resistance and fungal pathogenesis of C. albicans.” Funded by SERB-DST (2016-2019)
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