Flavin-Induced Oligomerization in Escherichia coli Adaptive Response Protein AidB
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Drennan_Flavin-induced.pdf
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Author(s)
Hamill, Michael J.
Jost, Marco
Wong, Cintyu
Elliott, Sean J.
Drennan, Catherine L
Date Issued
October 2011
Journal
Biochemistry
Publisher
American Chemical Society (ACS)
Citation
Hamill, Michael J. et al. “Flavin-Induced Oligomerization in Escherichia Coli Adaptive Response Protein AidB.” Biochemistry 50.46 (2011): 10159–10169. Copyright 2011 American Chemical Society.
Version
Final published version
Abstract
The process known as “adaptive response” allows Escherichia coli to respond to small doses of DNA-methylating agents by upregulating the expression of four proteins. While the role of three of these proteins in mitigating DNA damage is well understood, the function of AidB is less clear. Although AidB is a flavoprotein, no catalytic role has been established for the bound cofactor. Here we investigate the possibility that flavin plays a structural role in the assembly of the AidB tetramer. We report the generation and biophysical characterization of deflavinated AidB and of an AidB mutant that has greatly reduced affinity for flavin adenine dinucleotide (FAD). Using fluorescence quenching and analytical ultracentrifugation, we find that apo AidB has a high affinity for FAD, as indicated by an apparent dissociation constant of 402.1 ± 35.1 nM, and that binding of substoichiometric amounts of FAD triggers a transition in the AidB oligomeric state. In particular, deflavinated AidB is dimeric, whereas the addition of FAD yields a tetramer. We further investigate the dimerization and tetramerization interfaces of AidB by determining a 2.8 Å resolution crystal structure in space group P32 that contains three intact tetramers in the asymmetric unit. Taken together, our findings provide strong evidence that FAD plays a structural role in the formation of tetrameric AidB.
MIT Department
Massachusetts Institute of Technology. Department of Biology
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/bi201340t
