UmuD2 Inhibits a Non-covalent Step during DinB-mediated Template Slippage on Homopolymeric Nucleotide Runs
Year: 2010
Type: article
Abstract: Escherichia coli DinB (DNA polymerase IV) possesses an enzyme architecture resulting in specialized lesion bypass function and the potential for creating -1 frameshifts in homopolymeric nucleotide runs. We have previously shown that the mutagenic potential of DinB is regulated by the DNA damage response protein UmuD(2). In the current study, we employ a pre-steady-state fluorescence approach to gain a mechanistic understanding of DinB regulation by UmuD(2). Our results suggest that DinB, like its mammalian and archaeal orthologs, uses a template slippage mechanism to create single base deletions on homopolymeric runs. With 2-aminopurine as a fluorescent reporter in the DNA substrate, the template slippage reaction results in a prechemistry fluorescence change that is inhibited by UmuD(2). We propose a model in which DNA templates containing homopolymeric nucleotide runs, when bound to DinB, are in an equilibrium between non-slipped and slipped conformations. UmuD(2), when bound to DinB, displaces the equilibrium in favor of the non-slipped conformation, thereby preventing frameshifting and potentially enhancing DinB activity on non-slipped substrates.
Source: Journal of Biological Chemistry
Institutions: Massachusetts Institute of Technology, Yale University
Language: English
Topic: DNA Repair Mechanisms
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1984710872