Number of DNA repair enzymes and frequency of damaged bases excised

Range ~10^5 repair enzymes/cell: Excised damaged bases are 1 every 10^6 bp
Organism Bacteria Escherichia coli
Reference Pollak AJ, Chin AT, Reich NO. Distinct facilitated diffusion mechanisms by E. coli Type II restriction endonucleases. Biochemistry. 2014 Nov 18 53(45):7028-37. doi: 10.1021/bi501110r. p.7034 right column 2nd paragraphPubMed ID25350874
Primary Source [12] Friedman, Joshua I. & Stivers, James T. Detection of Damaged DNA Bases by DNA Glycosylase Enzymes. Biochemistry (2010), 49 (24), 4957-4967 doi: 10.1021/bi100593a. [15] Hedglin, Mark O'Brien, Patrick J. Hopping Enables a DNA Repair Glycosylase To Search Both Strands and Bypass a Bound Protein. ACS Chemical Biology (2010), 5 (4), 427-436 doi: 10.1021/cb1000185.PubMed ID20469926, 20201599
Comments P.7034 right column 2nd paragraph: "Repair enzymes have high cellular copy numbers (∼10^5) and excise damaged bases that are very rare (1 every 10^6 bp)(primary sources). Therefore, in vivo processive catalysis is unlikely, and a scenario where each enzyme is confined to shorter stretches of genomic DNA seems probable. Furthermore, Dam readily skips sites (methylation marks separated by 1 kb are sufficient for mismatch repair, whereas each site is typically separated by only ∼250 bp), whereas the repair of each target by UNG [uracil DNA glycosylase] is more critical, and rigorous and repetitive searching of local regions is necessary. Biological context is clearly connected to the combination of translocation mechanisms that a particular protein will use, and [investigators'] study here reveals this for two closely related enzymes."
Entered by Uri M
ID 113298