Linkage map of Escherichia coli K-12, edition 8.

https://mmbr.asm.org/content/mmbr/60/1/44.full.pdf

Histidine biosynthetic pathway and genes: structure, regulation, and evolution.

Secreted hemolysins were extremely common among clinical isolates of Proteus mirabilis, Proteus vulgaris, and Morganella morganii, and hemolytic activity was either cell associated or cell free. Southern hybridization of total DNA from hemolytic isolates to cloned regions of the Escherichia coli alpha-hemolysin (hly) determinant showed clear but incomplete homology between genes encoding production of hemolysins in the four species. One of the two E. coli secretion genes, hlyD, hybridized only with DNA from P. vulgaris and M. morganii, which produced cell-free hemolysis, but not with that from P. mirabilis, which showed only cell-associated activity. Molecular cloning of the genetic determinants of cell-free hemolytic activity from P. vulgaris and M. morganii chromosomal DNA allowed their functional analysis via inactivation with the transposons Tn1000 and Tn5. Both hemolysin determinants were about 7.5 kilobase pairs and comprised contiguous regions directing regulation, synthesis, and specific secretion out of the cell. Transposon mutations which eliminated secretion of the Proteus and Morganella hemolysins could be complemented specifically by the E. coli hemolysin secretion genes hlyB or hlyD. Alignment of the physically and functionally defined hly determinants from P. vulgaris and M. morganii with that of the E. coli alpha-hemolysin confirmed a close genetic relationship but also indicated extensive evolutionary divergence.

The secreted hemolysins of Proteus mirabilis, Proteus vulgaris, and Morganella morganii are genetically related to each other and to the alpha-hemolysin of Escherichia coli.

This map is an update of the edition 9 map by Berlyn et al. (M. K. B. Berlyn, K. B. Low, and K. E. Rudd, p. 1715–1902, in F. C. Neidhardt et al., ed., Escherichia coli and Salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). It uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. The latter are included as synonyms. An alphabetical list of genes showing map location, synonyms, the protein or RNA product of the gene, phenotypes of mutants, and reference citations is provided. In addition to genes known to correspond to gene sequences, other genes, often older, that are described by phenotype and older mapping techniques and that have not been correlated with sequences are included.

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Linkage Map of Escherichia coli K-12, Edition 10: The Traditional Map

We have isolated cDNA clones representing cyclic AMP (cAMP)-specific phosphodiesterases (PDEases) from a human monocyte cDNA library. One cDNA clone (hPDE-1) defines a large open reading frame of ca. 2.1 kilobases, predicting a 686-amino-acid, ca. 77-kilodalton protein which contains significant homology to both rat brain and Drosophila cAMP PDEases, especially within an internal conserved domain of ca. 270 residues. Amino acid sequence divergence exists at the NH2 terminus and also within a 40- to 100-residue domain near the COOH-terminal end. hPDE-1 hybridizes to a major 4.8-kilobase mRNA transcript from both human monocytes and placenta. The coding region of hPDE-1 was engineered for expression in COS-1 cells, resulting in the overproduction of cAMP PDEase activity. The hPDE-1 recombinant gene product was identified as a low-Km cAMP phosphodiesterase on the basis of several biochemical properties including selective inhibition by the antidepressant drug rolipram. Known inhibitors of other PDEases (cGMP-specific PDEase, cGMP-inhibited PDEase) had little or no effect on the hPDE-1 recombinant gene product. Human genomic Southern blot analysis suggests that this enzyme is likely to be encoded by a single gene. The presence of the enzyme in monocytes may be important for cell function in inflammation. Rolipram sensitivity, coupled with homology to the Drosophila cAMP PDEase, which is required for learning and memory in flies, suggests an additional function for this enzyme in neurobiochemistry.

Cloning and expression of cDNA for a human low-Km, rolipram-sensitive cyclic AMP phosphodiesterase

We present the nucleotide sequence of the galactokinase gene (galK) of Escherichia coli including its 5' and 3' flanking regions. This DNA sequence derives from the lambda gal8 transducing phage and is identical to the sequence present in the galK gene fusion vectors, pKO and pKG, commonly used to study transcriptional regulatory elements. We define the precise 3' junction between the bacterial and phage sequences in lambda gal8 and demonstrate that this junction probably results from a homologous recombination event between identical 9 bp sequences common to the gal operon and phage lambda. Moreover, we examine the 300 bp region located immediately beyond galK for transcription termination function and find no gal operon terminator. Lastly, we compare the galK genes of E. coli and the yeast S. cerevisiae and find several regions of strong homology among which is a potential ATP-binding site homology shared by a variety of ATP-binding proteins including protein kinases encoded by mammalian oncogenes.

Structure of the galactokinase gene of Escherichia coli , the last (?) gene of the gal operon

We fused segments of the Escherichia coli his regulatory region to galK in single-copy and multicopy vectors. These fusions demonstrated that (i) derepression of his by histidine starvation is due exclusively to attenuation; (ii) the his promoter is metabolically regulated; and (iii) both regulatory systems operate when the his regulatory region is present on a multicopy plasmid. Thus, there is no evidence for titration of his regulatory elements. Deletions of the his anti-attenuator region, carried on multicopy plasmids, cause low-level galK expression. This expression is not stimulated by histidine starvation, but is growth rate dependent. We replaced the his attenuator with the efficient lambda terminator, to. In the context of the his regulatory region, however, lambda to only partially terminates transcription.

K. McKenney

Papers

Structure of the galactokinase gene of Escherichia coli , the last (?) gene of the gal operon

Regulation of single and multicopy his operons in Escherichia coli.