Molecular cloning of the Drosophila Fanconi anaernia gene FANCD2 cDNA

Fanconi anaemia(FA)is a rare disease characterized by chromosome instability and cancer susceptibility. With the exception of FANCD2, none of the Fanconi anaemia genes are conserved in evolution, limiting the study of the Fanconi anaernia pathway in genetically tractable models. Here we report the cloning and sequencing of a Drosophila full length cDNA homologous to human FANCD2 (dmFANCD2) as a first step in using Drosophila in Fanconi anaemia research. dmFANCD2 is composed of 14 exons coding for a protein of 1478 aminoacids. Southern blot and in situ hybridization analysis indicated that dmFANCD2 is present at single copy in the Drosophila genome and maps at the chromosomal band 92-F3. Sequence and structural biocomputational analysis indicated that, although the aminoacidic sequence, and specially the N-terminus region, is not highly conserved between humans and flies (23% identity and 43% similarity), both proteins are of the same size, globular and compact, with several transmembrane helixes and related to nuclear membrane proteins. Interestingly, the human ATM phosphorylation site at S222 and the complex-dependent monoubiquitination site at K561 are highly conserved in Drosophila at positions S267 and K595, respectively. The same is true for other putative ATM sites and their aminoacidic environment and for two out of three aminoacid mutations associated with human pathology. These results suggest that the key FANCD2 features have been conserved during over 500 million years of divergent evolution, highlighting their biological importance. (C) 2003 Elsevier Science B.V. All rights reserved.