title: Rolling replication of short DNA circles.
abstract: Natural genes and proteins often contain tandemly repeated sequence motifs that dramatically increase physiological specificity and activity. Given the selective value of such repeats, it is likely that several different mechanisms have been responsible for their generation. One mechanism that has been shown to generate relatively long tandem repeats (in the kilobase range) is rolling circle replication. In this communication, we demonstrate that rolling circle synthesis in a simple enzymatic system can produce tandem repeats of monomers as short as 34 bp. In addition to suggesting possible origins for natural tandem repeats, these observations provide a facile means for constructing libraries of repeated motifs for use in "in vitro evolution" experiments designed to select molecules with defined biological or chemical properties.
authors.affiliation: Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21210, USA.
authors.forename: A
authors.initials: A
authors.lastname: Fire
authors.forename: S Q
authors.initials: SQ
authors.lastname: Xu
mesh_terms: D001483:Base Sequence; D005075:Biological Evolution; D011088:DNA Ligases / Q000378:metabolism; D004256:DNA Polymerase I / Q000378:metabolism*; D004261:DNA Replication; D004270:DNA, Circular / Q000096:biosynthesis* / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D004270:DNA, Circular; D009838:Oligodeoxyribonucleotides; D004256:DNA Polymerase I; D011088:DNA Ligases