title: Inhibition of DNA synthesis facilitates expansion of low-complexity repeats: is strand slippage stimulated by transient local depletion of specific dNTPs?
abstract: Simple DNA repeats (trinucleotide repeats, micro- and minisatellites) are prone to expansion/contraction via formation of secondary structures during DNA synthesis. Such structures both inhibit replication forks and create opportunities for template-primer slippage, making these repeats unstable. Certain aspects of simple repeat instability, however, suggest additional mechanisms of replication inhibition dependent on the primary DNA sequence, rather than on secondary structure formation. I argue that expanded simple repeats, due to their lower DNA complexity, should transiently inhibit DNA synthesis by locally depleting specific DNA precursors. Such transient inhibition would promote formation of secondary structures and would stabilize these structures, facilitating strand slippage. Thus, replication problems at simple repeats could be explained by potentiated toxicity, where the secondary structure-driven repeat instability is enhanced by DNA polymerase stalling at the low complexity template DNA.
authors: Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA. kuzminov@life.illinois.edu
authors: Andrei
authors: A
authors: Kuzminov
mesh_terms: D004247:DNA / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D017931:DNA Primers; D004261:DNA Replication / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D003854:Deoxyribonucleotides / Q000378:metabolism*; D053842:Microsatellite Instability; D018895:Microsatellite Repeats; D018598:Minisatellite Repeats; D009690:Nucleic Acid Conformation; D013698:Templates, Genetic; D018911:Trinucleotide Repeats
chemical_list: D017931:DNA Primers; D003854:Deoxyribonucleotides; D004247:DNA; D004259:DNA-Directed DNA Polymerase