ETD at Indian Institute of Science
Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.
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Studies On The Mechanisms Involved In Thymic Atrophy During Salmonella Enterica Serovar Typhimurium Infection - Deobagkar-Lele, Mukta
T lymphocytes are an essential component of the adaptive immune response and are highly versatile in function. Each T cell has a unique T cell receptor that can recognize an antigenic peptide in the context of the major his to compatibility complex (MHC) encoded molecules, thus offering a high degree of specificity to the immune response. T cells play a central role in the development of an effective host immune response and the quantitative and qualitative regulation of the T cell response is critical. T cells develop in the thymus, an important primary immune organ, where immature thymocytes undergo differentiation...
Characterization Of Structural And Non-structural Proteins Of Positive Sense, Single-stranded RNA Plant Viruses - Mathur, Chhavi
In the present thesis, two positive sense single-stranded RNA viruses have been used as models to understand the structure and function of viral-encoded proteins. One of them, Pepper Vein Banding Virus (PVBV; genus Potyvirus; family Potyviridae) is a flexuous, rod-shaped virus that encodes for a polyprotein of size ~340 kDa. The polyprotein undergoes proteolytic processing by viral-encoded proteases, of which Nuclear Inclusion-a Protease (NIa-Pro) is the major protease. It is a serine-like cysteine protease which cleaves between a Q/A or Q/S, present in the context of the heptapeptide recognition sequence. The temporal regulation of intermediates and mature proteins released by...
Glycodelin-A As The Regulator Of CD8+ T-Lymphocyte Activity : Implications In Primate Pregnancy - Soni, Chetna
The ability of our immune system to mount a response against non-self-antigens legitimates the semi-allogenic fetus as a target for maternal immune attack. Yet, in a normal pregnancy the fetus stays well protected due to the concerted action of several diverse mechanisms which either suppress the fetal allogenicity or spatio-temporally inhibit maternal immune cells’ growth and functions.
One such factor which aids in the establishment, progression and maintenance of pregnancy is the 28 kDa dimeric sialylated glycoprotein Glycodelin-A (GdA). Synthesized by the endometrium and decidua, this protein has myriad functions, the most important being that of immunosuppression. GdA is inhibitory...
Biochemical Characterization Of An Acid-Adaptive Type III DNA Methyltransferase From Helicobacter Pylori 26695 And Its Biological Significance - Banerjee, Arun
Enzyme DNA methylation is an important biochemical process that imprints DNA with additional information. DNA methylation is catalyzed by S-adenosyl-L-methionine (AdoMet)-dependent methyltraferases (MTases). Prokaryotic DNA MTases are usually components of restriction-modification(R-M) systems that enable cells to resist propagation of foreign genomes that would otherwise kill them. Based on the position methyl group transfer on the bases in DNA, MTases are classified into two groups-exocyclic or amino MTases and endocyclic or ring MTases. The amino MTases methylate exocyclic amino nitrogen to form either N6-methyladenine or n4-methycytosine. N6-methyaladenine is mostly found in the genomes of bacteria, archaea protists and fungi.
Insights Into Transcription-Repair Coupling Factor From Mycobacterium Tuberculosis - Swayam Prabha, *
Nucleotide excision repair (NER) is a highly conserved pathway involved in repair of a wide variety of structurally unrelated DNA lesions. One of the well characterized NER systems is from E. coli which involves UvrABC nucleases. NER consists of two related sub-pathways: global genomic repair (GGR), which removes lesions from the overall genome, and transcription coupled repair (TCR), which removes lesions from the transcribed strand of active genes. Bulky DNA lesions such as cyclobutane pyrimidine photodimers (CPD) induced by UV irradiation block RNA polymerase (RNAP) during transcription. In bacteria, a gene product of mfd called transcription repair coupling factor...
Studies On The Functional Roles Of Peptidase N, A M1 Family Member, During Stress And Infection - Bhosale, Manoj
The cytosolic protein degradation pathway, performed by ATP-dependent proteases and ATP-independent peptidases, plays important roles in several cellular activities, e.g. cell division, cell cycle progression, intracellular signaling, MHC class I antigen presentation, host-pathogen interactions, etc. The roles of ATP-dependent proteases during stress and infection have been studied in great detail but the functional roles of ATP-independent peptidases are not clearly understood. In this study, the functional roles of E. coli or S. typhimurium encoded Peptidase N (PepN), an ATP-independent enzyme belonging to theM1 family of metallopeptidases, were investigated. The thesis will address four different aspects.
(i) In the first part,...
The Mechanism Of Fragility Of The BCL2 And HOX11 Breakpoint Regions During t(14;18) And t(10;14) Chromosomal Translocations In Lymphoid Cancers - Nambiar, Mridula
Haematological cancers like leukemia and lymphoma are characterized by genetic abnormalities, specifically chromosomal translocations. Analyses of the translocation breakpoint regions in patients have shown that some loci in the genome are more susceptible to breakage than others. However, very little is known about the mechanism of generation of many such chromosomal translocations. In the present study, we have attempted to understand the mechanism of fragility of three regions, which are prone to breaks during translocations in follicular lymphoma (FL) and T-cell leukemia. The t(14;18) translocation in FL is one of the most common chromosomal translocations. Most breaks on chromosome 18...
Mechanism Of RAG Action As A Structure-Specific Nuclease : Implications In Genomic Instability In Lymphoid Cells - Naik, Abani Kanta
Recombination Activating Genes (RAGs) orchestrate the process called V (D) J recombination, which enables the vertebrate adaptive immune system to specifically recognize millions of antigens. During this recombination process, V (variable), D (diversity) and J (joining) gene segments of antibody (B cell receptor) and TCR (T cell receptor) join by different possible combinations to generate antigen receptor diversity. This unique site specific recombination process is actuated by lymphoid specific proteins called RAG1 and RAG2 (RAGs or RAG complex). RAGs recognize a conserved sequence motif flanking the above subexons called Recombination Signal Sequence (RSS). There are two types of RSS known...
Characterization Of HP1369-HP1370 From Helicobacter Pylori : A Novel ε Type N6 –Adenine Methyltransferase - Chaudhary, Awanish Kumar
Helicobacter pylori is one of the most genetically diverse bacterial species that successfully colonizes at least 50% of the world population. It has been associated with humans for thousands of years and most probably evolved from ancestral gastric Helicobacter species in early mammals. One of the important characteristics of this pathogen is the degree of allelic diversity and genetic variability which helps it to adapt and colonize. Phase variation is one of the mechanisms used by H. pylori to generate variation. The presence of homopolymeric nucleotide or dinucleotide repeats in an ORF make it prone to frequent length changes as...
Exploring The Role Of Purinergic Signaling In T Cell Activation - Bhate, Monali M
Adenosine 5’ triphosphate (ATP) is a molecule central to life for its role as the
cellular energy currency, and a purine nucleotide which serves as a building block of RNA. Thus, on the backdrop of an indispensible intracellular role of ATP, its identification as an extracellular signaling molecule in early 1970s came as a surprise. A novel doctrine, termed as ‘purinergic signaling’, was thus put forth. By definition, purinergic signaling consists of
the signaling events triggered by binding of extracellular ATP- a purine nucleotide, and its breakdown products (viz., ADP, AMP, and adenosine) to their cognate receptors, which in turn are termed...
Production Of Anticancer Drug Taxol And Its Precursor Baccatin III By Fusarium Solani And Their Apoptotic Activity On Human Cancer Cell Lines - Chakravarthi, B V S K
Taxol (generic name paclitaxel), a plant‐derived antineoplastic agent, was
originally isolated from the bark of the Pacific yew, Taxus brevifolia. Obtaining
taxol from this source requires destruction of trees. It has been used alone or in
combination with other chemotherapeutic agents for the treatment of breast,
ovarian as well as many other types of cancer, including non‐small cell lung
carcinoma, prostate, head and neck cancer, and lymphoma, as well as AIDSrelated
Kaposi’s sarcoma. The mode of action of taxol against a number of human cancer cells is by preventing the depolymerization of tubulin during cell division. This molecule increases microtubule stability in the cell and induces...
Processing Of DNA Recombination And Replication Intermediates By Mycobacterium Tuberculosis RuvA And RuvB Proteins - Khanduja, Jasbeer Singh
Homologous recombination (HR) is a highly conserved cellular process involved in the
maintenance of chromosomal integrity and generation of genetic diversity. Biochemical and genetic studies have suggested that HR is crucial for repair of damaged DNA arising from various endogenous or exogenous assaults on the genome of any organism. Further, HR is vital to repair fatal DNA damage during DNA replication. An instructive example of cross-talk between the processes of DNA recombination and replication can be construed in the processing of replication/recombination/repair intermediates. The impediment(s) to the progression of DNA replication fork is one of the underlying causes for increased genome...
Insights Into The Mechanism Of Polyprotein Processing Of Sesbania Mosaic Virus And Characterization Of The Polyprotein Domains - Nair, Smita
1. Viruses are obligate parasites that hijack the host cell machinery to synthesize
their own gene products and for their propagation. In order to establish a
successful viral infection, viruses have evolved different strategies to evade
host check points. Further more, their success also relies in employing varied
strategies to express maximum number of functional proteins from their small
constrained genome. Polyprotein processing is a widely used strategy of
expression by many plant viruses. With limited information available on this
aspect for sobemoviruses, the present study was undertaken.
2. The present thesis deals with the mechanism of Sesbania mosaic virus (SeMV) polyprotein processing and functional characterization of the...
Molecular Cloning And Characterization Of A Calcium-Depdendent Protein Kinase Isoform ScCPK1 From Swainsona Canescens - Srideshikan, S M
Plants are constantly exposed to pathogens and various environmental stresses, such as cold, salinity and drought. Plants normally respond rapidly to these biotic and abiotic stresses. Efficient perception of biotic and abiotic stresses and cell programmed signaling mechanisms for appropriate responses are important for growth and survival of plants. Calcium is an important second messenger in signaling pathways that respond to environmental stresses, pathogen attack as well as hormonal stimuli (For review, see DeFalco et al., 2010; Reddy and Reddy, 2004; Sanders et al., 2002). The transient increase of cytosolic free calcium concentration has been shown in a variety of...
Biochemical Characterization Of Heat Shock Protein 90 From Plasmodium Falciparum - Pallavi, Rani
Molecular chaperones are a group of proteins which maintain cellular homeostasis by assisting de novo protein folding and their refolding to native state after destabilization due to external stress. They are also known as heat shock proteins as they were first discovered as a response to heat stress. It is now well established that the function of this group of proteins is not only restricted to protein homeostasis but also extends to diverse cellular processes such signal transduction, development and differentiation.
Heat shock protein 90 (Hsp90) is one of the most abundant molecular chaperones that is highly conserved from prokaryotes...
Helicobacter Pylori Restriction-Modification Systems : Possible Roles Beyond Genome Protection - Kumar, Ritesh
Helicobacter pylori is one of the most potential and successful human pathogen which colonizes atleast 50% of world population. One of the important characteristics of this pathogen is the degree of allelic diversity and genetic variability which helps it to adapt and colonize. Phase variation is one of the mechanisms used by Helicobacter pylori to generate variation, where presence of homopolymeric nucleotide or dinucleotide repeats in an ORF make it prone to frequent length changes as a consequence of slipped strand mispairing mediated mutagenesis.
An important feature of H. pylori biology is the presence of a large number of Restriction-Modification (R-M)...