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Promoter utilization in a mosquito ribosomal DNA cistron

Park, Y.J., Baldridge, G.D., Fallon, A.M.
Archives of insect biochemistry and physiology 1995 v.28 no.2 pp. 143-157
Aedes albopictus, ribosomal DNA, ribosomal RNA, structural genes, nucleotide sequences, DNA probes, DNA-binding proteins, DNA-directed RNA polymerase, promoter regions, transcription (genetics), binding sites
In the mosquito Aedes albopictus, two potential RNA polymerase I promoters that map 531 and 143 nucleotides upstream of the 18S rRNA gene have been defined on the basis of sequence homology with rRNA promoters from other species. Using the polymerase chain reaction, we confirmed that a 717 nucleotide region spanning the upstream (-531) and downstream (-143) promoters is homogeneous in genomic DNA and in cloned DNA. DNA probes representing each of these promoters, as well as upstream "spacer" promoters, exhibited protein-binding activity, and each unlabeled probe was an effective competitor of protein binding with the other probes, suggesting that these potential regulatory sequences interact with a common protein(s). Analysis of precursor ribosomal RNAs accumulated during temperature shock indicated that transcription is initiated primarily at the upstream (-531) promoter. RNAse protection and primer extension analyses confirmed the predominant use of this promoter, both in cultured cells and in mosquito life stages.