Molecular dissection of Helicobacter pylori Topoisomerase I reveals an additional active site in the carboxyl terminus of the enzyme

Kondekar, SM and Gunjal, GV and Pablo Radicella, J and Rao, DN (2020) Molecular dissection of Helicobacter pylori Topoisomerase I reveals an additional active site in the carboxyl terminus of the enzyme. In: DNA Repair, 91-92 (102853).

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Abstract

DNA topoisomerases play a crucial role in maintaining DNA superhelicity, thereby regulating various cellular processes. Unlike most other species, the human pathogen Helicobacter pylori has only two topoisomerases, Topoisomerase I and DNA gyrase, the physiological roles of which remain to be explored. Interestingly, there is enormous variability among the C-terminal domains (CTDs) of Topoisomerase I across bacteria. H. pylori Topoisomerase I (HpTopoI) CTD harbors four zinc finger motifs (ZFs). We show here that sequential deletion of the third and/or fourth ZFs had only a marginal effect on the HpTopoI activity, while deletion of the second, third and fourth ZFs severely reduced DNA relaxation activity. Deletion of all ZFs drastically hampered DNA binding and thus abolished DNA relaxation. Surprisingly, mutagenesis of the annotated active site tyrosine residue (Y297 F) did not abrogate the enzyme activity and HpTopoI CTD alone (spanning the four ZFs) showed DNA relaxation activity. Additionally, a covalent linkage between the DNA and HpTopoI CTD was identified. The capacity of HpTopoI CTD to complement Escherichia coli topA mutant strains further supported the in vitro observations. Collectively these results imply that not all ZFs are dispensable for HpTopoI activity and unveil the presence of additional non-canonical catalytic site(s) within the enzyme. © 2020 Elsevier B.V.

Item Type:	Journal Article
Publication:	DNA Repair
Publisher:	Elsevier B.V.
Additional Information:	Copyright of this article belongs to Elsevier B.V.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	31 Mar 2021 11:44
Last Modified:	31 Mar 2021 11:44
URI:	http://eprints.iisc.ac.in/id/eprint/65585

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