The Drosophila melanogaster gene for the NADH : ubiquinone oxidoreductase acyl carrier protein: developmental expression analysis and evidence for alternatively spliced forms

We have isolated the Drosophila melanogaster gene encoding the mitochondria l acyl carrier protein (mtACP), a subunit of NADH:ubiquinone oxidoreductase involved in de novo fatty acid synthesis in the mitochondrion. This gene e xpresses two distinct mature transcripts by alternative splicing, which enc ode mature polypeptides of 86 (mtACP1A) and 88 (mtACP1B) amino acids, respe ctively. Drosophila mtACP1 is 72% identical to mammalian mtACP, 47% identic al to Arabidopsis thaliana mtACP, and 46% identical to Neurospora crassa mt ACP. The most highly conserved region encompasses the site that binds pante theine-4'-phosphate in all known ACPs. Southern analysis of genomic DNA and in situ hybridization to salivary gland chromosomes indicate that a single gene (mtacp1)? located at 61F6-8, encodes the two isoforms of D. melanogas ter mtACP1. Sequence analysis revealed that the gene contains four exons an d that exons IIIA and IIIB are alternatively spliced. A P-element-induced l oss-of-function mutation in the mtacp1 gene causes lethality, indicating th at the gene is essential for viability. Developmental Northern analysis sho ws that mtacp1 is expressed at higher levels during late embryogenesis, in the pupa and in the adult. RNA in situ hybridization on embryos indicates t hat the mtacp1 gene is highly expressed in the tracheal system. Zygotic mta cp1 function is required for both male and female gametogenesis.