DmTTF, a novel mitochondrial transcription termination factor that recognises two sequences of Drosophila melanogaster mitochondrial DNA.
Using a combination of bioinformatic and molecular biology approaches a Drosophila melanogaster protein, DmTTF, has been identified, which exhibits sequence and structural similarity with two mitochondrial transcription termination factors, mTERF (human) and mtDBP (sea urchin). Import/processing assays indicate that DmTTF is synthesised as a precursor of 410 amino acids and is imported into mitochondria, giving rise to a mature product of 366 residues. Band-shift and DNase I protection experiments show that DmTTF binds two homologous, short, non-coding sequences of Drosophila mitochondrial DNA, located at the 3' end of blocks of genes transcribed on opposite strands. The location of the target sequences coincides with that of two of the putative transcription termination sites previously hypothesised. These results indicate that DmTTF is the termination factor of mitochondrial transcription in Drosophila. The existence of two DmTTF binding sites might serve not only to stop transcription but also to control the overlapping of a large number of transcripts generated by the peculiar transcription mechanism operating in this organism.
Roberti
Marina
M
Dipartimento di Biochimica e Biologia Molecolare, Università di Bari, CNR, Via Orabona 4, 70125 Bari, Italy.
Polosa
Paola Loguercio
PL
Bruni
Francesco
F
Musicco
Clara
C
Gadaleta
Maria Nicola
MN
Cantatore
Palmiro
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites / Q000235:genetics; D001692:Biological Transport; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D008930:Mitochondria, Liver / Q000378:metabolism; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D011485:Protein Binding; D051381:Rats; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D050976:Basic-Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D004272:DNA, Mitochondrial; D029721:Drosophila Proteins; C105178:MTERF1 protein, human; D024101:Mitochondrial Proteins; D014157:Transcription Factors