M. Bibbins et al., DAB1 - A DEGENERATE RETROTRANSPOSON-LIKE ELEMENT FROM NEUROSPORA-CRASSA, MGG. Molecular & general genetics, 258(4), 1998, pp. 431-436
A repeated DNA sequence in the genome of Neurospora crassa has been id
entified as a family of degenerate retroelements. Retroelements encode
protein sequences with clear homology to the reverse transcriptase, R
Nase H and endonuclease products of the pol genes common to retrovirus
es and retrotransposons. These sequence comparisons place the N. crass
a element within the gypsy group of retrotransposons, akin to other el
ements found in filamentous fungi. However, the Neurospora element is
defective, as no flanking long terminal repeats (LTRs) could be distin
guished and the pol gene homologues contain numerous stop codons as a
result of multiple base substitutions. The base composition of the ele
ment displays significant under-representation of the dinucleotide CpA
, the preferred target site of repeat-induced point mutation (RIP). Th
e genomic sequences exhibit G:C to A:T transitions between copies whic
h are diagnostic of RIP. The degenerate retroelement has accordingly b
een designated by the acronym dab-1 (dead and buried).