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Identification of post translational modifications of human Topoiosmerase 1 in the presence of camptothecin and CHK1 inhibitor SCH900776.

ABSTRACT: Topisomerase 1 (TOP1), an essential enzyme in humans, plays a critical role in relaxation of DNA supercoils during replication and transcription. The TOP1 reaction cycle involves an obligate TOP1-DNA covalent complex intermediate (TOP1cc), which is stabilized by TOP1 poisons like camptothecin. While cellular responses to potentially genotoxic TOP1ccs are widely studied, the regulation of TOP1 catalytic cycle itself inside the cell in poorly understood. In the current study, we have demonstrated a regulatory role of the master checkpoint kinase CHK1 in regulating the TOP1 catalytic cycle inside cells. We performed an in silico prediction of CHK1 cognate sites on TOP1. In order to validate the same, we isolated catalytically engaged TOP1 from human genomic DNA, and performed mass spectrometric analysis. Our analysis revealed one previously unreported putative CHK1 cognate site to be phosphorylated on TOP1 inside cells. We further employed site directed mutagenesis, molecular and cellular assays to establish the role played by CHK1 in regulating TOP1 catalysis.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Birija Patro

LAB HEAD: Dr. Birija Sankar Patro

PROVIDER: PXD055870 | Pride | 2026-03-16

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	CPT_1UM.raw	Raw
	CPT_200NM.raw	Raw
	MULTICONSENSUS-FILE.pdResult	Other
	SCH_2H.raw	Raw
	SCH_6H.raw	Raw

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