Understanding the defence mechanism of CRISPR-Cas subtype I-C of Leptospira interrogans

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dc.contributor.authorAnand, Vineet
dc.date.accessioned2024-12-13T10:06:11Z
dc.date.available2024-12-13T10:06:11Z
dc.date.issued2024
dc.descriptionSupervisor: Kumar, Manish
dc.description.abstractLeptospira interrogans is a bacterium that causes Leptospirosis. However, its pathogenicity is poorly understood due to the lack of effective conventional genetic manipulation tools. L. interrogans serovar (sv.) Copenhageni encodes two CRISPR-Cas systems - I-B and I-C in its genome. The presence of the CRISPR-Cas system in the genome of pathogenic Leptospira has been hypothesized as the reason for low success in genetic manipulation and, hence, deciphering its virulent gene function. The CRISPR-Cas I-B locus in L. interrogans has been extensively studied. However, CRISPR-Cas I-C lacks an array element, making it an interesting subject to investigate its Cas protein's role in CRISPR biology. The CRISPR-Cas I-C locus encodes all sets of proteins required for adaptation (LinCas1C, LinCas2C, and LinCas4C), maturation (LinCas5C), and interference (LinCas7C, LinCas8C, LinCas3C, and LinCas3Cʹ). Moreover, the genes encoding these proteins are transcriptionally active. The nucleotide sequence and encoded amino acids of the cas genes show low sequence similarity with subtype I-B and are phylogenetically distantly related. The adaptation Cas protein (LinCas1C, LinCas2C, and LinCas4C) exhibits metal-ion-dependent DNase and metal-ion-independent RNase activity under in vitro conditions. However, neither rLinCas1C nor LinCas2C demonstrates any activity towards small DNA oligos, except for rLinCas4C. The crystal structure analysis of rLinCas2C shows that it adopts a dimeric conformation, and each subunit exhibits the characteristic ferredoxin fold. The crystal structure of rLinCas2C indicates its existence in a catalytically inactive conformational state. The substitution mutation of active site residues (Tyr7, Asp8, Arg33, and Phe39) of rLinCas2C with Ala and deletion mutation of RNA recognition loop (Asp60, Lys62, Thr63, and Asp64) resulted in compromised DNase activity.
dc.identifier.otherROLL NO.166106104
dc.identifier.urihttps://gyan.iitg.ac.in/handle/123456789/2763
dc.language.isoen
dc.relation.ispartofseriesTH-3470
dc.titleUnderstanding the defence mechanism of CRISPR-Cas subtype I-C of Leptospira interrogans
dc.typeThesis
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