‘IIN trpA gene product was analyzed from a class of strains of Escherichia coli I112 in which the lac operon has been fused by deletion t,o the trp operon. These are strains that have retained the ability to synthesize tryptophan. Two of these strains are shown to make a wild-type trpA product ; these strains retain intact all structural genes of the trp operon. It is proposed that the lac oper...

Bistability in the lac operon of Escherichia coli has been widely studied, both experimentally and theoretically. Experimentally, bistability has been observed when E. coli is induced by an artificial, nonmetabolizable, inducer. However, if the lac operon is induced with lactose, the natural inducer, bistability has not been demonstrated. We derive an analytical expression that can predict the ...

The abilities of 14 tryptophan analogs to repress the tryptophan (trp) operon have been studied in Escherichia coli cells derepressed by incubation with 0.25 mM indole-3-propionic acid (IPA). trp operon expression was monitored by measuring the specific activities of anthranilate synthase (EC 4.1.3.27) and the tryptophan synthase (EC 4.2.1.20) beta subunit. Analogs characterized by modification...

During infection, Yersinia pestis uses its F1 capsule to enhance survival and cause virulence to mammalian host. Since F1 is produced in large quantities and secreted into the host tissues, it also serves as a major immune target. To hold this detrimental effect under proper control, Y. pestis expresses the caf operon (encoding the F1 capsule) in a temperature-dependent manner. However, additio...

The E-arabinose operon is under both positive and negative control by the product of its regulatory gene, UrQc. We have measured transcription of the arabinose genes by hybridization of 3H-labeled messenger RNA to single-stranded DNA from an arabinose transducing phage in order to study the effect of the regulatory gene on transcription. In strains in which the arabinose regulatory gene is comp...

The Prokaryotic Operon DataBase (ProOpDB, http://operons.ibt.unam.mx/OperonPredictor) constitutes one of the most precise and complete repositories of operon predictions now available. Using our novel and highly accurate operon identification algorithm, we have predicted the operon structures of more than 1200 prokaryotic genomes. ProOpDB offers diverse alternatives by which a set of operon pre...

The dnaK operon of Streptomyces coelicolor contains four genes (5'-dnaK-grpE-dnaJ-hspR). The fourth gene encodes a novel heat shock protein, HspR, which appears so far to be unique to the high-G+C actinomycete group of bacteria. HspR binds with high specificity to three inverted repeat sequences in the promoter region of the S. coelicolor dnaK operon, strongly suggesting a direct role for HspR ...

The E-arabinose operon is under both positive and negative control by the product of its regulatory gene, UrQc. We have measured transcription of the arabinose genes by hybridization of 3H-labeled messenger RNA to single-stranded DNA from an arabinose transducing phage in order to study the effect of the regulatory gene on transcription. In strains in which the arabinose regulatory gene is comp...

The discovery of a novel multicistronic operon that encodes phosphofructokinase, pyruvate kinase, and lactate dehydrogenase in the lactic acid bacterium Lactococcus lactis is reported. The three genes in the operon, designated pfk, pyk, and ldh, contain 340, 502, and 325 codons, respectively. The intergenic distances are 87 bp between pfk and pyk and 117 bp between pyk and ldh. Plasmids contain...