ISSN:
1617-4623
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract A 50 kb region of DNA fromStreptomyces violaceoruber Tü22, containing genes encoding proteins involved in the biosynthesis of granaticin, was isolated. The DNA sequence of a 7.3 kb fragment from this region, located approximately 10 kb from the genes that encode the polyketide synthetase responsible for formation of the benzoisochromane quinone skeleton, revealed five open reading frames (ORF1-ORF5). The deduced amino acid sequence of GraE, encoded by ORF2, shows 60.8% identity (75.2% similarity) to a dTDP-glucose dehydratase (StrE) fromStreptomyces griseus. Cultures ofEscherichia coli containing plasmids with ORF2, on a 2.1 kbBamHI fragment, were able to catalyze the formation of dTDP-4-keto-6-deoxy-d-glucose from dTDP-glucose at 5 times the rate of control cultures, confirming that ORF2 encodes a dTDP-glucose dehydratase. The amino acid sequence encoded by ORF3 (GraD) is 51.4% identical (69.9% similar) to that of StrD, a dTDP-glucose synthase fromStreptomyces griseus. The amino acid sequence encoded by ORF4 shares similarities with proteins that confer resistance to tetracycline and methylenomycin, and is suggested to be involved in transporting granaticin out of the cells by an active efflux mechanism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02423457
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