title: Intervening sequences in human fetal globin genes adopt left-handed Z helices.
abstract: The large intervening sequences ( IVS2 ) of three human fetal globin genes contain tracts of alternating purine-pyrimidine sequences approximately 40-60 base pairs in length which adopt left-handed Z DNA helices under the influence of negative supercoiling. The amount of negative supercoiling (approximately 0.045) required for the right- to left-handed transitions is within the physiological range. The structural aberrations between the right- and left-handed helices were mapped by sequencing the S1 nuclease cleavage sites. Two-dimensional gel electrophoretic analyses of the supercoil-induced relaxation served to characterize the type and length of left-handed structure. Furthermore, binding studies with several types of antibodies confirmed the presence of left-handed helices. Since these simple sequences appear to be hotspots for recombination and gene conversion, unusual DNA conformations may participate in genetic expression.
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000032:analysis*; D004278:DNA, Superhelical / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004720:Endonucleases / Q000378:metabolism; D005260:Female; D005319:Fetal Hemoglobin / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D009690:Nucleic Acid Conformation; D011247:Pregnancy; D015719:Single-Strand Specific DNA and RNA Endonucleases
chemical_list: D004278:DNA, Superhelical; D004247:DNA; D005319:Fetal Hemoglobin; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases