ISSN:
1476-5535
Keywords:
Nosiheptide resistance
;
Thiopeptide antibiotics
;
Streptomyces
;
Antitermination
;
Regulation of transcription
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Summary The nosiheptide resistance gene (nshR) and a putative regulatory gene (nshA) are found together on a 2326 bpBamHI-PstI DNA fragment isolated fromStreptomyces actuosus ATCC 25421. The putative regulatory gene,nshA, situated upstream from the nosiheptide resistance gene in the 2326 bp DNA fragment, contains apparent DNA-binding and RNA-binding domains. Interruption ofnshA in the chromosome ofS. actuosus alters nosiheptide production, suggesting thatnshA is involved in regulation of nosiheptide biosynthesis. Two transcription initiation sites were found upstream ofnshA as demonstrated by high-resolution Sl nuclease mapping. A weak transcription start site fornshR was found which initiated transcription from the first nucleotide of the open reading frame. Although a stem-loop structure with apparent termination activity was found betweennshA andnshR, readthrough of transcription betweennshA andnshR was demonstrated by S1 nuclease mapping of the 3′ terminus of thenshA transcript. Time-course S1 experiments of the three promoters (nshA-pl, nshA-p2, nshR-p) indicated highly regulated differential expression of the promoters.nshA-p2 is a strong, constitutive promoter whereasnshA-pl being regulated temporally with maximal activity at 96 h. Approximately 30% of the totalnshA-p1/p2 transcript reads through the terminator and into thenshR gene, accounting for more than half of the total steady-statenshR transcript. The implications of the regulation ofnshA andnshR gene expression, as well as the expression of two other linked genes, are presented.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01575585
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