Biomaterial Database

Derepression of colicin E1 synthesis in the constitutive tif mutant strain (spr tif sfi) and in a tif sfi mutant strain of Escherichia coli K-12. 1978

E S Tessman, and C A Gritzmacher, and P K Peterson

We show here that expression of the colicin gene of the ColE1 plasmid is greatly derepressed in Escherichia coli K-12 strain DM1187 spr tif sfi, which is a constitutive tif mutant, altered in the lexA gene, and which shows constitutive expression of various pathways of the recA-dependent, lexA-blocked (SOS) repair system. In this strain colicin E1 synthesis is at least 100-fold greater than that observed in uninduced control strains (spr+ tif sfi and spr+ tif+ sfi). This result confirms the regulatory role of the lexA product in colicin E1 synthesis. Colicin yields by the uninduced strain DM1187 are as high as the maximum yields from mitomycin-induced control strains and often are several-fold higher. When the nonconstitutive tif sfi strain GC467 is raised to 43 degrees C to induce the SOS system, a low level of colicin synthesis is observed which is less than one-tenth of the yield obtained by induction with mitomycin C. Addition of adenine at the time of shift-up can increase the colicin yield of tif sfi to about one-third of the yield obtained with mitomycin C. We have also found that colicin overproduction can be detected by altered colony appearance in an overlay assay with colicin-sensitive bacteria. In addition, the lethality of the process of colicin synthesis is observed here without the use of bacteriostatic inducing agents.

UI	MeSH Term	Description	Entries
D008937	Mitomycins	A group of methylazirinopyrroloindolediones obtained from certain Streptomyces strains. They are very toxic antibiotics used as ANTINEOPLASTIC AGENTS in some solid tumors. PORFIROMYCIN and MITOMYCIN are the most useful members of the group.
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D003086	Bacteriocin Plasmids	Plasmids encoding bacterial exotoxins (BACTERIOCINS).	Bacteriocin Factors,Col Factors,Colicin Factors,Colicin Plasmids,Bacteriocin Factor,Bacteriocin Plasmid,Col Factor,Colicin Factor,Colicin Plasmid,Factor, Bacteriocin,Factor, Col,Factor, Colicin,Factors, Bacteriocin,Factors, Col,Factors, Colicin,Plasmid, Bacteriocin,Plasmid, Colicin,Plasmids, Bacteriocin,Plasmids, Colicin
D003087	Colicins	Bacteriocins elaborated by strains of Escherichia coli and related species. They are proteins or protein-lipopolysaccharide complexes lethal to other strains of the same species.	Colicin,Colicin E9,Colicine,Colicines,Colicin A,Colicin B,Colicin E,Colicin E1,Colicin E2,Colicin E3,Colicin E8,Colicin HSC10,Colicin Ia,Colicin Ib,Colicin K,Colicin K-K235,Colicin M,Colicin N,Colicin V,Colicins E,Colicins E9,Precolicin E1,Colicin K K235,E9, Colicin
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot