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dc.contributor.advisorSuguna, K
dc.contributor.authorBhandari, Spraha
dc.date.accessioned2018-12-02T04:22:05Z
dc.date.available2018-12-02T04:22:05Z
dc.date.submitted2017
dc.identifier.urihttps://etd.iisc.ac.in/handle/2005/4175
dc.description.abstractSmall Heat Shock Proteins (sHSP) are ATP-independent molecular chaperones that exhibit diversity in structure, function and mode of action. They are present ubiquitously in all kingdoms of life. They function mainly by preventing the aggregation of non-native and destabilised proteins during stress as well as normal conditions. Their subunit molecular weight ranges from 12 kDa to 42 kDa and exist as higher order oligomers in their resting or native state. Structurally, these proteins have a tripartite domain organization with a structured α-crystallin domain (ACD) at the centre flanked by variable and flexible N-terminal domain and C-terminus. The protomers associate into dimers, which further assemble into higher order structures. The N-termini is longer than the C-termini, harbour sites for post-translational modifications, usually found buried within the oligomer and are required for substrate recognition and binding. The C-termini on the otherhand, harbour a conserved motif, called the I-X-I motif which facilitate formation of higher order structures. The thesis reports the structural and functional characterisation of three sHSPs (M1, M2 and M3) and their deletion constructs from Mycobacterium marinum M. In mycobacteria, these proteins are immunodominant antigens and are also used as biomarkers for disease identification. All the three proteins formed oligomers of different stoichiometry as determined through Size exclusion chromatography-Multi angle light scattering (SEC-MALS) experiments. Lysozyme aggregation assay was performed for assessing the ATP-independent molecular chaperone activity of these proteins. M1 and M3 were observed to be active while M2 was inactive. From the three sHSPs, one of the proteins, M3, crystallised and hence was taken up for structural investigations. The protein crystallised in different conditions and the structure was determined using data from a Se-Met derivative (Se-SAD) and molecular replacement (MR) phasing in space groups I23 (at 2.8 Å and 2.0 Å resolution, respectively) and C2221 (3.75 Å). The structure was a dodecamer with a cage-like architecture, exhibiting a 23 symmetry. The dodecameric assembly was observed to be hydrophobic inside and hydrophilic outside. The I-X-I mode of interaction, as observed in other sHSP structures, formed the dimer-dimer association and stabilized the cage. Electron micrographs collected for M3 protein, further confirmed that the structure reported was a dodecamer in solution. Further, on comparison of the high resolution sHSP structure of M3 with other reported structures, a similar arrangement of trimers was observed. This is the first report of a high resolution sHSP crystal structure from mycobacteria.en_US
dc.language.isoen_USen_US
dc.relation.ispartofseriesG28667;
dc.rightsI grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertationen_US
dc.subjectsHSPsen_US
dc.subjectBacterial Small Heat Shock Proteinen_US
dc.subjectM. marinumen_US
dc.subjectSmall Heat Shock Proteinsen_US
dc.subjectM. marinum sHSPen_US
dc.subjectMycobacterium marinum Men_US
dc.subjectsHSPen_US
dc.subject.classificationMolecular Biophysicsen_US
dc.subject.classificationsHSPen_US
dc.titleStructural and Functional Characterisation of Small Heat Shock Protiens from Mycobacterium Marinum Men_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.grantorIndian Institute of Scienceen_US
dc.degree.disciplineFaculty of Scienceen_US


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