The ability to form intrastrand tetraplexes is an evolutionarily conserved feature of the 3' end of L1 retrotransposons.
Mammalian genomes contain many thousands of members of a family of retrotransponsons known as L1 (or LINE-1) elements. These elements lack long terminal repeats (LTRs), and are thought to use a retroposition mechanism than differs from that of retroviruses and other LTR-containing retroelements. In order to define those regions of the L1 element that may be important for L1 retroposition, we examined the 3' untranslated regions (UTRs) of L1 elements from a diverse group of mammals. We show that while the 3' UTRs of L1 elements from different species share little if any sequence homology, they all contain a G-rich polypurine tract of variable length and sequence which can form one or more intrastrand tetraplexes. This conservation over the 100 Myr since the mammalian radiation suggests that either the G-rich motif itself or a conserved structure such as the tetraplex that can be formed by this motif is a significant structural feature of L1 elements and may play a role in their propagation.
Howell
R
R
Section on Genomic Structure and Function, National Institute of Diabetes, and Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Usdin
K
K
D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D019143:Evolution, Molecular; D006801:Humans; D006860:Hydrogen Bonding; D008322:Mammals / Q000235:genetics; D051379:Mice; D008956:Models, Chemical; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D011817:Rabbits; D018626:Retroelements; D012689:Sequence Homology, Nucleic Acid; D012788:Shrews / Q000235:genetics
D017931:DNA Primers; D018626:Retroelements; D004247:DNA