Functional analysis of Drosophila melanogaster hexokinase Hex-A locus: multiple Initiator-like elements enhance DPE containing promoter activity.
Flight muscle Hexokinase-A (HEX-A) is the most conserved and essential hexokinase isoenzyme among Drosophila species. In this study, the Hex-A locus, encoding the HEX-A isoenzyme, has been analysed for the elements regulating its expression. By sequencing the 5' ends of Hex-A cDNA amplified by 5' RACE, we identified a transcription start site that overlapped the Initiator and downstream promoter elements. A 214 bp sequence, encompassing transcription start sites and promoter elements, was required for minimal promoter activity. DNA sequence to the 5' end of the minimal promoter element did not demonstrate any promoter activity; however, its inclusion with the basal promoter element enhanced the promoter activity. Oligonucleotide competition and site-directed mutagenesis identified the Initiator-like sequences, TCAWT, present in this region that were responsible for enhancing the promoter activity. The Hex-A locus is expressed as a single protein in Drosophila cell line, whereas in pupae, larvae and adult flies, it is expressed as two distinct types.
Jayakumar
P C
PC
National Center for Cell Science, University of Pune Campus, Ganeshkhind, Maharashtra, Pune 411 007, India.
Shouche
Y S
YS
Patole
M S
MS
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002874:Chromosome Mapping; D004331:Drosophila melanogaster / Q000201:enzymology* / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D006593:Hexokinase / Q000235:genetics*; D007527:Isoenzymes; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014176:Protein Biosynthesis; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
D007527:Isoenzymes; D006593:Hexokinase