TTAA serves as the target site for TFP3 lepidopteran transposon insertions in both nuclear polyhedrosis virus and Trichoplusia ni genomes

Abstract

We have analysed TFP3 transposable elements from five independently isolated FP mutants of the Autographa californica nuclear polyhderosis virus (AcMNPV). We also analysed genomic copies of TFP3 elements amplified from the DNAs of the Trichoplusia ni cell line (TN-368) and T. ni larvae using the polymerase chain reaction (PCR). The sequences of all the newly isolated TFP3 elements closely resemble the previously described TFP3/1 element. Each of the transposons isolated from the virus mutants duplicated a TTAA tetranucleotide target site upon insertion into the viral genome. Four of these TFP3 elements transposed into three different 'TTAA' target sites within the 25 K gene (FP locus, map units 36-37 of AcMNPV). The fifth TFP3 element inserted at a 'TTAA' site within the AcMNPV Hin dIII-E fragment. One genomic TFP3 element, amplified from the TN-368 cell line DNA by an inverse PCR method, duplicated a 'TTAA' tetranucleotide target site that is present only once in the homologous larval DNA sequence. These data suggest that mobilization of TFP3 into both viral and cellular sites is identical in specificity and mechanism.

The lepidopteran transposon vector, piggyBac , mediates germ-line transformation in the Mediterranean fruit fly

“…Studies to date have only detected piggyBac in T. ni, and other TTAA elements have been found solely in a limited number of lepidopteran species (17)(18)(19). Thus, the apparently restricted existence of piggyBac, in comparison to other short inverted terminal repeat elements such as P, hobo, and mariner, is intriguing given the present demonstration of its normal mobility in a distantly related species.…”

“…It is part of a subclass of ITR elements that are thus far found only in lepidopterans and that insert exclusively into TTAA target sites (17)(18)(19). On insertion, the target site is duplicated with excision occurring only in a precise fashion, restoring the insertion site.…”

Phantom, a New Subclass ofMutatorDNA Transposons Found in Insect Viruses and Widely Distributed in Animals

“…These HT events were caught in the act during experiments in the laboratory. More recently, a reptilian SINE was identified bioinformatically in the genome of the taterapox virus that infects mammals, revealing that HT of TEs to viruses occurs in nature (Wang and Fraser 1993;Ozers and Friesen 1996;Piskurek and Okada 2007). Interestingly, we have identified Phantom transposases and/or complete Phantom elements in two double-stranded polydsDNA viruses, Gf.…”

“…Indeed, TEs have been previously identified in viral genomes. For example, piggybac and TED were identified when they passed from the Lepidopteran host to the infectious baculovirus (Lerch and Friesen 1992;Wang and Fraser 1993). These HT events were caught in the act during experiments in the laboratory.…”

Excision and transposition of piggyBac transposable element in tobacco budworm embryos

“…PiggyBac inserts in the center of the tetranucleotide TTAA, which is duplicated upon insertion (Wang and Fraser, 1993). Upon excision, the target insertion site can be restored, leaving no footprint (Fraser et al, 1996).…”