AI Article Synopsis
- The umuD gene products are crucial in how E. coli responds to DNA damage, transitioning from UmuD(2) to a modified form UmuD'(2) as part of the SOS response.
- Damage-induced interactions lead to a structural change in UmuD that allows for both mutagenic and non-mutagenic DNA synthesis.
- A specific mutation (N41D) in UmuD allows it to function as a monomer, effectively mimicking the dimeric form and contributing to DNA repair and cell viability after UV damage.
Article Abstract
The homodimeric umuD gene products play key roles in regulating the cellular response to DNA damage in Escherichia coli. UmuD(2) is composed of 139-amino acid subunits and is up-regulated as part of the SOS response. Subsequently, damage-induced RecA·ssDNA nucleoprotein filaments mediate the slow self-cleavage of the N-terminal 24-amino acid arms yielding UmuD'(2). UmuD(2) and UmuD'(2) make a number of distinct protein-protein contacts that both prevent and facilitate mutagenic translesion synthesis. Wild-type UmuD(2) and UmuD'(2) form exceptionally tight dimers in solution; however, we show that the single amino acid change N41D generates stable, active UmuD and UmuD' monomers that functionally mimic the dimeric wild-type proteins. The UmuD N41D monomer is proficient for cleavage and interacts physically with DNA polymerase IV (DinB) and the β clamp. Furthermore, the N41D variants facilitate UV-induced mutagenesis and promote overall cell viability. Taken together, these observations show that a monomeric form of UmuD retains substantial function in vivo and in vitro.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3030365 | PMC |
| http://dx.doi.org/10.1074/jbc.M110.167254 | DOI Listing |
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