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J Bacteriol. 1988 Nov;170(11):5018-26.

Characterization of a cyanobacterial iron stress-induced gene similar to psbC.

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  • 1Department of Botany, University of Toronto, Ontario, Canada.

Abstract

Recently we have reported that the flavodoxin gene from the cyanobacterium Anacystis nidulans R2 is transcribed as part of an iron stress-induced operon containing multiple mRNA species (D. E. Laudenbach, M. E. Reith, and N. A. Straus, J. Bacteriol. 170: 258-265, 1988). Here we report that nucleotide sequence analyses of DNA located immediately upstream of the flavodoxin gene revealed an open reading frame of 1,026 bases (designated isiA; iron stress inducible) with a deduced amino acid sequence showing similarity to that of the psbC polypeptide of higher plants and cyanobacteria. Assuming proteolytic cleavage of the initial methionine residue, the open reading frame encodes a 341-amino-acid polypeptide with a molecular mass of 36,824 daltons. Amino acid sequence comparisons with known psbC polypeptides from spinach and A. nidulans R2 showed extensive similarity, especially in the proposed membrane-spanning regions. Mung bean nuclease mapping and primer extension experiments have localized a transcriptional start site to a position 19 bases upstream from the first methionine codon of the isiA gene product. The upstream region contains an Escherichia coli-like -10 sequence but lacks the typical -35 consensus sequence. Approximately 15, 25, and 150 bases upstream from the isiA transcription start site are 17 base sequences which resemble the operator sequences of iron-regulated genes of E. coli.

PMID:
3141374
PMCID:
PMC211566
[PubMed - indexed for MEDLINE]
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