CLONING AND MOLECULAR CHARACTERIZATION OF A VOLTAGE-DEPENDENT ANION-SELECTIVE CHANNEL (VDAC) FROM DROSOPHILA-MELANOGASTER

A full length voltage-dependent anion-selective channel (VDAC) cDNA wa s cloned from Drosophila melanogaster by expression library screening using an antibody against an insect VDAC protein. The cDNA clone (deno ted DmVDAC) is 1082 base pairs (bp) in length and contains an open rea ding frame (bp 62-907) encoding a 282 amino acid protein which has a p redicted molecular mass of 30 550 Da, a predicted pI of 6.98 and no cy steines. Hydrophobicity analysis suggests 15 or 16 membrane-spanning d omains. The DmVDAC amino acid sequence has variable homology with VDAC s from other species ranging from 62% identity with a human VDAC to 23 % identity with a Dictyostelium discoideum VDAC. DmVDAC has 92% identi ty with the 38 conserved residues in a VDAC consensus sequence, DmVDAC was expressed in VDAC-null yeast but failed to rescue viability. DmVD AC has 88% identity at the amino acid level and 99% identity at the nu cleic acid level with a recently reported D. melanogaster VDAC sequenc e (A. Messina et al., FEBS Lett. 384 (1996) 9-13). Homology analyses w ith the Messina and other VDAC sequences indicate that the amino acid differences are due to minor errors in the Messina sequence. Southern blots and chromosomal in situ hybridizations suggest a single VDAC gen e occurs in the fly with a locus at 32B on the left arm of the second chromosome. (C) 1997 Elsevier Science B.V.