A partial restriction map of the proApurE region of the Escherichia coli K-12 chromosome

Hadley, R. G.; Hu, Ming; Timmons, Michael; Kwok, Yun; Deonier, Richard C.

doi:10.1016/0378-1119(83)90113-0

Cited by 28 publications

(11 citation statements)

References 27 publications

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“…The computer program SRCHN (28) (30), and the original construction of phage Xp phoA', used for generating sequencing clones, involved a lac operon fusion (31,32).…”

Section: Resultsmentioning

confidence: 99%

DNA sequence of the lactose operon: the lacA gene and the transcriptional termination region.

Hediger¹,

Johnson²,

Nierlich³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

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The lac operon of Escherichia coli spans approximately 5300 base pairs and includes the lacZ, lacY, and WA genes in addition to the operator, promoter, and transcription termination regions. We report here the sequence of the IacA gene and the region distal to it, confirming the sequence of thiogalactoside transacetylase and completing the sequence of the lac operon. The lacA gene is characterized by use of rare codons, suggesting an origin from a plasmid, transposon, or virus gene. UUG is the translation initiation codon. A preliminary examination of 3' end of the lac messenger in the region distal to 'the lacA gene indicates several endpoints. A predominant one is located at the 3' end of a G+C-rich hairpin structure, which may be involved in termination of transcription or in post-transcriptional processing.An 'open reading frame of 702 base pairs is present on the complementary strand downstream from kacA.Since its description more than 25 years ago, the lactose operon has been a model system of great usefulness in biology. Indeed, study of one or another aspect of the lactose operon has touched on many of the most significant questions of biology. For example, the fundamental question of the mechanisms involved in expression ofgenes was first studied in this system (1). The discovery of the lac repressor and its binding to an operator site on DNA (2, 3) was one of the first problems concerning protein-DNA interactions to be examined. Studies of P-galactosidase in relation to mutants in lacZ have been important in defining many aspects of gene-protein relationships (4). Studies with fragments of f3-galactosidase also have served as a model system for investigating protein-protein interactions (5). The lactose permease, the product of the second structural gene, lacy, was the first membrane transport protein studied extensively (6). Many fundamental concepts ofthe transport of molecules into the cell were derived from these studies. Thiogalactoside transacetylase, which is the gene product of lacA, the third structural gene, has been something of a mystery. The most reasonable interpretation of its function is that it is involved in detoxification (7). As indicated by the experiments of Andrews and Lin (7), cells containing the transacetylase are able to overcome inhibition of growth by thiogalactosides under certain conditions. It is not surprising, therefore, that structures of the components ofthe lactose operon have also been investigated intensively. The amino acid sequence of the lac repressor was determined many years ago (8), and the amino acid sequence ofI-galactosidase was reported in 1977 (9). Both of these proteins were examined by classical methods ofprotein chemistry. When methods for determining DNA sequences became available, the DNA sequence of the control elements of the lactose operon was one of the first to be studied (10).More recently, the DNA sequence of lacZ was determined (11), with the amino acid sequence of f-galactosidase as confirmation (12). The DNA sequence of lac'Y also...

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“…The computer program SRCHN (28) (30), and the original construction of phage Xp phoA', used for generating sequencing clones, involved a lac operon fusion (31,32).…”

Section: Resultsmentioning

confidence: 99%

DNA sequence of the lactose operon: the lacA gene and the transcriptional termination region.

Hediger¹,

Johnson²,

Nierlich³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

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“…All three activities were restored in sexductants of strain MC4100 A(argF-lac) which carried F'2, i.e., strain FF101. Thus, the 35-kilobase-pair chromosomal insert of this plasmid, which covers part of the argF-codAB region (14), appears to contain several loci governing glycine betaine synthesis. There are few gene markers in this region of the E. coli chromosome, and the bet genes are the first chromsomal genes found on F'2.…”

Section: Methodsmentioning

confidence: 99%

Selection, mapping, and characterization of osmoregulatory mutants of Escherichia coli blocked in the choline-glycine betaine pathway

Styrvold¹,

Falkenberg²,

Landfald³

et al. 1986

J Bacteriol

130

109

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Osmotically stressed Escherichia coli cells synthesize the osmoprotectant glycine betaline by oxidation of cholibe through glycine betaine aldehyde (choline -* glycine betalne aldehyde glycine betaine;Landfald and A. R. Str0m, J. Ilacteriol. 165:849-855, 1986. Mutants blocked at the level of choline dehydrogenase were isolated by selection of strains which did not grow at elevated osmotic strength in the presence of choline but grew when supplemented with glycine betaine. A gene governing the choline dehydrogenase activity was named betA. Mapping by P1 transduction, F' complementation, and deletion mutagenesis showed the betA gene to be located at 7.5 min in the argF-codB region of the chromosome. Mutants carrying deletions of this region also lacked glycine betaine aidehyde dehydrogeniase activity and high-affinity uptake activity for choline; these deletions did not influence the activities of glycine betalne uptake or low-affinity choline uptake, both of which were osmotically regulated.Glycine betaine is accumulated under osmotic stress in widely different-organisms such as chemoheterotrophic bacteria (16, 22, 26-28, 33. 35), halotolerant photosynthetic bacteria (12, 29, 34), marine animals, and halophytic plants (36,37). Whereas the biological activity of glycine betaine in osmoregulation cannot -be easily demonstrated for higher organisms, this is possible for Esckerichia coli and other enteric bacteria. Addition of relatively low concentrations (e.g., 1 mM) of glycine betaine or its precursors choline or glycine betaine aldehyde to medium of inhibitory osmotic strength stimulates the growth of these bacteria (11,22,(26)(27)(28)35). In the companion paper (22) we show that the choline-glycine betaine pathway of E. coli contains two enzymes: a membrane-bound, 02-dependent choline dehydrogenase and a soluble, NAD-dependent glycine betaine aldehyde dehydrogenase. The pathway is osmotically regulated, i.e., appreciable dehydrogenase activities are synthesized only in cells grown -under osmotic stress. Thus, glycine betaine synthesis ard accumulation in E. coli represent an intriguing system for studies of the molecular mechanism of osmotic tolerance (27). In this communication we describe the selection and characterization of mutants blocked in the choline-glycine betaine pathway. Genes governing several critical activities including choline and glycine betaine aldehyde oxidation and choline uptake were mapped -on -the chromosome of E. coli. MATERIALS AND METHODSBacterial and bacteriophage strains. The strains used are listed in Table 1. The betA mutations-generated in K10 were transferred to CSH7 by P1 transduction and conjugation.

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“…In Escherichia coli, the heme genes encoding these enzymes are widely scattered on the genome (2,3,15,26). Two of the heme genes in E. coli have been cloned and sequenced: hemC (porphobilinogen deaminase [PBG-D]) (39) and hemD (urogen cosynthase) (31).…”

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confidence: 99%

Cloning of the Escherichia coli K-12 hemB gene

Umanoff

Proenca

et al. 1988

J Bacteriol

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An Escherichia coli heme-requiring, heme-permeable mutant had no detectable 5-aminolevulinate dehydratase or porphobilinogen deaminase activities. The gene which complemented this mutation was cloned to a high-copy-number plasmid, and porphobilinogen deaminase activity was restored to normal levels, but the synthesis of 5-aminolevulinate dehydratase increased 20- to 30-fold. A maxicell procedure confirmed that the gene cloned was hemB.

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A partial restriction map of the proApurE region of the Escherichia coli K-12 chromosome

Cited by 28 publications

References 27 publications

DNA sequence of the lactose operon: the lacA gene and the transcriptional termination region.

DNA sequence of the lactose operon: the lacA gene and the transcriptional termination region.

Selection, mapping, and characterization of osmoregulatory mutants of Escherichia coli blocked in the choline-glycine betaine pathway

Cloning of the Escherichia coli K-12 hemB gene

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