Unusual structures of TTTA repeats in icaC gene of Staphylococcus aureus.
One and two TTTA repeat expansions have been found in the coding region of icaC gene of Staphylococcus aureus variants which influence the expression of IcaC protein and alter the phenotype. Yet, the mechanism of these small-size TTTA repeat expansions remains unclear. In this study, we performed high-resolution nuclear magnetic resonance spectroscopic studies on TTTA repeats. Our results show that a DNA sequence containing three TTTA repeats can fold into dumbbell structures with a 3' or 5'-overhang. Exchange of these dumbbells makes the sequence behave like a 2-nt TT mini-loop at 25°C. The occurrence of these mini-loop and dumbbell structures in the nascent strand during DNA replication provides possible mechanistic pathways which account for one and two repeat expansions.
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Pei
P
Guo
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong. Electronic address: lams@cuhk.edu.hk.
Sik Lok
SL
Lam
D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D042622:DNA Repeat Expansion; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry* / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005798:Genes, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism
D018829:Adhesins, Bacterial; D004269:DNA, Bacterial; D020033:Protein Isoforms; D021122:Protein Subunits
DNA structure; Nuclear magnetic resonance; Slipped strand mispairing; Staphylococcus aureus; TTTA repeat expansion