THE E-SUBUNIT GENE OF MURINE F1F0-ATP SYNTHASE - GENOMIC SEQUENCE, CHROMOSOMAL MAPPING, AND DIET REGULATION

Genomic sequences encoding murine Lfm1, whose predicted protein sequen ce is 96% and 98% similar to bovine and rat F1F0-ATP synthase e subuni ts (respectively), have been amplified from BALB/cByJ DNA, cloned, and sequenced. The 1,1-kilobase gene has 3 introns and 4 exons, and its c oding sequence differs by two nucleotides compared to the previously p ublished BALB/cHnn Lfm1 cDNA sequence. A PstI restriction site polymor phism in intron 2 between C57BL/6J and Mus spretus was used to map thi s gene to Chromosome 5 near D5Mit9. Related sequences mere mapped on C hromosomes 8, 11, and 2 unlinked loci on Chromosome 2 using Southern b lot analyses with the 1.1-kilobase gene as probe. Previous studies fro m this laboratory indicated that the Lfm1/e subunit was regulated by t he level of dietary fat and carbohydrate. Northern hybridization analy ses demonstrated that e subunit mRNA abundance showed statistically si gnificant differences (p < 0.025) between hearts of BALB/c mice fed 3% and those fed 20% corn oil for 2 weeks and in liver (p < 0.05) from t he same animals. Significant differences were also observed in hepatic and heart mRNA expression at different times after eating in animals subjected to a fast/refeed regimen. The implications of the high degre e of sequence similarity to the e subunit for rat and bovine F1F0-ATP synthase and its regulation by diet are discussed.