Analysis of genome sequences is enabling identification of numerous novel characteristics that provide valuable means for genetic and biochemical studies. Of these characteristics, Conserved Signature Indels (CSIs) in proteins which are specific for a given group of organisms have proven particularly useful for evolutionary and biochemical studies. My research work focused on using comparative genomics techniques to identify a large number of CSIs which are distinctive characteristics of fungi and other important groups of organisms. These CSIs were utilized to understand the evolutionary relationships among different proteins (species), and also regarding their structural features and functional significance. Based on multiple CSIs that I have identified for the PIP4K/PIP5K family of proteins, different isozymes of these proteins and also their subfamilies can now be reliably distinguished in molecular terms. Further, the species distribution of CSIs in the PIP4K/PIP5K proteins and phylogenetic analyses of these protein sequences, my work provides important insights into the evolutionary history of this protein family. The functional significance of one of the CSI in the PIP5K proteins, specific for the Saccharomycetaceae family of fungi, was also investigated. The results from structural analysis and molecular dynamics (MD) simulation studies show that this 8 aa CSI plays an important role in facilitating the binding of fungal PIP5K protein to the membrane surface. In other work, we identified multiple highly-specific CSIs in the phosphoketolase (PK) proteins, which clearly distinguish the bifunctional form of PK found in bifidobacteria from its homologs (monofunctional) found in other organisms. Structural analyses and docking studies with these proteins indicate that the CSIs in bifidobacterial PK, which are located on the subunit interface, play a role in the formation/stabilization of the protein dimer. We have also identified 2 large CSIs in SecA proteins that are uniquely found in thermophilic species from two different phyla of bacteria. Detailed bioinformatics analyses on one of these CSIs show that a number of residues from this CSI, through their interaction with a conserved network of water molecules, play a role in stabilizing the binding of ADP/ATP to the SecA protein at high temperature. My work also involved developing an integrated software pipeline for homology modeling of proteins and analyzing the location of CSIs in protein structures. Overall, my thesis work establishes the usefulness of CSIs in protein sequences as valuable means for genetic, biochemical, structural and evolutionary studies. / Dissertation / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25115 |
| Date | January 2019 |
| Creators | Khadka, Bijendra |
| Contributors | Gupta, Radhey S., Biochemistry and Biomedical Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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