Nucleotide sequence of the Escherichia coli entE gene

The Escherichia coli entE gene encodes a polypeptide necessary in the latter stages of biosynthesis of the siderophore enterobactin. The entE gene and adjacent DNA were sequenced. The predicted EntE polypeptide consists of 536 amino acids and has a Mr of 58,299 and a net charge of -7.33. Genetic evidence combined with this and previous sequencing data indicate that the genes entCEB(G)A are transcribed as unit from a promoter upstream of entC.     

Nucleotide sequence of the Escherichia coli mutH gene.

The complete nucleotide sequence of mutH gene from E. coli has been determined. Based on the deduced amino acid sequence, the MutH protein has a molecular weight of 25.4 kdaltons in agreement with the previous estimates based on SDS-polyacrylamide gel electrophoresis of the purified protein. Deletion analysis of the DNA sequences upstream of mutH has identified the promoter region for this gene. Two independently isolated temperature sensitive alleles of the mutH gene have also been sequenced. One mutation results in an amino acid change at position 27 (thr to leu) while the other occurs at position 156 (asp to asn).     

Nucleotide sequence of the alkaline phosphatase gene of Escherichia coli

The nucleotide sequence of the alkaline phosphatase (APase) gene (phoA) of Escherichia coli strain 294 has been determined. Pre-APase has a total of 471 amino acids (aa) including a signal sequence of 21 aa. The derived aa sequence differs from that obtained by protein sequencing by the presence of aspartic acid instead of asparagine at positions 16 and 36, and glutamic acid instead of glutamine at position 197. Two open reading frames (ORF1 and ORF2) located downstream from phoA or upstream from proC have been found. ORF1 encodes a putative presecretory protein of 106 aa with a signal sequence of 21 or 22 aa. If this protein is actually produced, it may be one of the smallest periplasmic proteins in E. coli.     

Nucleotide sequence of the Escherichia coli replication gene dnaZX.

The Escherichia coli 2.2 kilobase dnaZX region contains one 1929 nucleotide reading frame which directs the synthesis of two protein products involved in DNA polymerization. The larger consists of 643 amino acids in a deduced 71,114 dalton chain which could be the tau subunit of DNA polymerase III. The smaller, the DNA polymerase III gamma subunit, is encoded by the same reading frame as the larger. The dnaZX sequence contains a region homologous to ATP binding sites, suggesting that these replication factors are adenine nucleotide binding proteins.     

Nucleotide sequence of the ethidium efflux gene from Escherichia coli

The nucleotide sequence of the gene specifying the ethidium efflux system of Escherichia coli has been determined. The translated open reading frame has identified a membrane-bound polypeptide of 110 amino acids (11,960 Da) which shares 42% identity with a staphylococcal protein specifying resistance to ethidium.     

Nucleotide sequence of the tag gene from Escherichia coli.

We have determined the complete nucleotide sequence of the tag gene, encoding 3-methyladenine DNA glycosylase I from Escherichia coli. From the nucleotide sequence it is deduced that the tag enzyme consists of 187 amino-acids and has a calculated molecular weight of 21.1 kdaltons. The tag enzyme is unusually rich in cysteine (8 residues) with a cluster of three consecutive cysteines near the C-terminal end. The tag coded DNA glycosylase does not show significant sequence homology to the alkA coded glycosylase in spite of that both of these enzymes catalyze the release of free 3-methyladenine from alkylated DNA.     

Nucleotide sequence of the respiratory D-lactate dehydrogenase gene of Escherichia coli

The structural gene for the respiratory D-lactate dehydrogenase of Escherichia coli, a membrane-bound flavoenzyme, has been subcloned from a 7 X 10(3)-base-pair chromosomal HindIII fragment containing the gene [Young, I. G., Jaworowski, A., and Poulis, M. (1982) Biochemistry 21, 2092-2095]. The complete nucleotide sequence of the 2340-base-pair PstI-SmaI subclone has been determined on both strands by the dideoxy chain termination method. A single large open reading frame is present in the nucleotide sequence. The reading frame is preceded by a good ribosome binding site and numerous possible promoter sequences, and is followed by a typical rho-independent termination sequence. The reading frame predicts that the D-lactate dehydrogenase polypeptide consists of 571 amino acids (including the initiating methionine residue) with Mr = 64613. The protein does not have a low overall polarity, nor does it contain unusually hydrophobic stretches. It appears to contain a short repeat which is homologous with the well characterized L-lactate dehydrogenases in the vicinity of the 'essential' cysteine residue. Apart from this, homology with other proteins of known sequence has not been detected.     

Nucleotide sequence of the Escherichia coli xanthine-guanine phosphoribosyl transferase gene.

The Escherichia coli gene coding for the enzyme xanthine-guanine phosphoribosyl transferase (gpt) has been widely used as a dominant selectable marker in a variety of mammalian cells. We have determined the complete nucleotide sequence of the 1057 base pair (bp) segment of DNA containing this gene. The coding sequence for the enzyme is 456 nucleotides long and can code for a 152 amino acid (16.9 Kd) polypeptide. A comparison of the amino acid sequence of the bacterial enzyme with that of the mammalian hypoxanthine-guanine phosphoribosyl transferase (hprt) reveals no significant homology between the two polypeptides.     

Nucleotide sequence of the Escherichia coli dnaJ gene and purification of the gene product

The dnaJ and dnaK genes are essential for replication of Escherichia coli DNA, and they constitute an operon, dnaJ being downstream from dnaK. The amount of the dnaJ protein in E. coli is substantially less than that of the dnaK protein, which is produced abundantly. In order to construct a system that over-produces the dnaJ protein, we started our study by determining the DNA sequence of the entire dnaJ gene, and an operon fusion was constructed by inserting the gene downstream of the lambda PL promoter of an expression vector plasmid, pPL-lambda. Cells containing the recombinant plasmid produced dnaJ protein amounting to 2% of the total cellular protein when cells were induced. The overproduced protein was purified, and Edman degradation of the protein indicated that the NH2-terminal methionine was found to be processed. From the DNA sequence of the dnaJ gene, the processed gene product is composed of 375 amino acid residues, and its molecular weight is calculated to be 40,975.