PMID:2172214

Citation	Staab, JF and Earhart, CF (1990) EntG activity of Escherichia coli enterobactin synthetase.J. Bacteriol. 172:6403-10
Abstract	The last steps in the biosynthesis of the Escherichia coli siderophore enterobactin (Ent) are carried out by Ent synthetase, a multienzyme complex believed to be composed of the entD, -E, -F, and -G products (EntD to -G). However, sequencing data showed that there is no separate entG gene and, unlike EntD to -F, no distinct EntG polypeptide has been identified. In this study, genetic, biochemical, and immunological approaches were used to study the anomalies associated with EntG activity. Two plasmids, pJS43 and pJS100, were isolated that had mutations resulting in truncated EntB proteins; both had the phenotype EntB+ EntG-. PJS43 had a Tn5 inserted 198 bp from the entB termination codon, and pJS100 had the last 25 codons of entB deleted. Plasmids isolated with Tn5 insertions in the 5' half of entB had the phenotype EntB- EntG+. These latter Tn5 mutations were EntB- EntG- when moved to the bacterial chromosome. Polyclonal antiserum was prepared and shown to react only with intact EntB in Western immunoblots. Addition of anti-EntB antiserum to Ent synthetase assays resulted in complete inhibition of enzyme activity, whereas preimmune serum had no effect. Lastly, AN462, the type strain for entG which was derived by Mu insertion and which has the phenotype EntB-G-A-, was characterized. Southern blot data showed a Mu insertion, presumably with polar effects, in the vicinity of the 5' end of entB. In summary, EntG activity was found to be encoded by the entB 3' terminus. The evidence, while not rigorously eliminating the possibility that a separate EntG polypeptide exists, strongly supports the idea that EntB is a bifunctional protein.
Links	PubMed
Keywords	Blotting, Southern; Cloning, Molecular; DNA Transposable Elements; DNA, Bacterial; Escherichia coli; Genetic Complementation Test; Genotype; Ligases; Multienzyme Complexes; Mutagenesis, Insertional; Nucleic Acid Hybridization; Plasmids; Restriction Mapping
edit table

Main Points of the Paper

Please summarize the main points of the paper.

Materials and Methods Used

Please list the materials and methods used in this paper (strains, plasmids, antibodies, etc).

Phenotype Annotations

See Help:AnnotationTable for details on how to edit this table.
<protect>

Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: MG1655 Substrain: 51145	Genotype of Reference Strain: entB+ Genotype of Experimental Strain : entB::Tn5 entG	Reference Condition:	0000267	increased gene expression	0000182	in vitro culture assay	A Tn5 was inserted 198 base pairs from the termination codon entB effecting the expression of entB and by extension entG.
edit table

</protect>

References

See Help:References for how to manage references in omp dev.