Cloning and expression of the Erwinia herbicola tyrosine phenol-lyase gene in Escherichia coli.

The tyrosine phenol-lyase (TPL) gene of Erwinia herbicola was cloned and expressed in Escherichia coli, and the complete nucleotide sequence of the gene determined. The TPL gene comprises 1368 bp, encoding 456 amino acids which have 90% amino acid identity with TPL from Citrobacter freundii. After replacing the 5'-flanking region of the TPL gene with the E. coli lac promoter, TPL protein could be hyperproduced constitutively in E. coli without induction by L-tyrosine.     

Nitrogen Fixation in a Biotype of Erwinia herbicola Resembling Escherichia coli

Two nitrogen-fixing members of the Enterobacteriaceae have been isolated from paper mill process water and compost. Although they closely resembled Escherichia coli , detailed biochemical characterization of these and 7 other isolates established that they should be assigned to a biotype of Erwinia herbicola . They may be distinguished from E. coli by their lack of amino acid decarboxylase activity, their ability to utilize cellobiose and malonate and to ferment cellobiose and amygdalin. In one of them, the capacity to fix nitrogen, ferment cellobiose and utilize malonate was resistant to the effects of ethidium bromide, acridine orange and sodium dodecyl sulphate, and the ability to utilize cellobiose could not be transferred on to E. coli or Salmonella typhi . It is therefore concluded that these characters are not carried on transferable plasmids. Forty-eight strains of E. coli of varying origin were examined for acetylene reducing activity and all were found to be negative. It is concluded that hitherto no naturally occurring strains of E. coli have been shown to fix nitrogen.     

Fructan from Erwinia herbicola.

Levan production by strains of Erwinia herbicola is common, and this property has some taxonomic significance for species differentiation within the "herbicola" group. The extracellular polysaccharide elaborated by strain 403 was characterized by nuclear magnetic resonance spectroscopy and methylation analysis. Results showed it to be a typical bacterial levan.     

Identification of carotenoids in Erwinia herbicola and in a transformed Escherichia coli strain

The yellow pigments of Erwinia herbicola Eho 10 and of a transformed Escherichia coli LE392 pPL376 have been identified as carotenoids. HPLC separation, spectra and in some cases mass spectroscopy demonstrated the presence of phytoene (15-cis isomer), beta-carotene (all-trans, 9-cis and 15-cis), beta-cryptoxanthin ( = 3-hydroxy beta-carotene), zeaxanthin (3,3'-dihydroxy beta-carotene) and corresponding carotene glycosides. In addition, lycopene and gamma-carotene accumulated in the presence of the inhibitor 2-(4-chlorophenylthio)-triethylamine.HCl. Carotenoid content in the transformed E. coli was two-fold higher than in E. herbicola. The pattern of the carotenoids was similar in the two organisms. Inactivation of the katF gene in E. coli resulted in an 85% lowering of carotenoid formation, as did the addition of 0.5% glucose to the medium. Suppression of carotenoid formation by inactivation of the katF gene lowered, but did not abolish, the protection offered by carotenoids against inactivation by alpha-terthienyl plus near-ultraviolet light (320-400 nm).     

Functional assignment of Erwinia herbicola Eho10 carotenoid genes expressed in Escherichia coli

Erwinia herbicola is a nonphotosynthetic bacterium that is yellow pigmented due to the presence of carotenoids. When the Erwinia carotenoid biosynthetic genes are expressed in Escherichia coli, this bacterium also displays a yellow phenotype. The DNA sequence of the plasmid pPL376, carrying the entire Erwinia carotenoid gene cluster, has been found to contain 12 open reading frames (ORFs). Six of the ORFs have been identified as carotenoid biosynthesis genes that code for all the enzymes required for conversion of farnesyl pyrophosphate (FPP) to zeaxanthin diglucoside via geranylgeranyl pyrophosphate, phytoene, lycopene, β-carotene, and zeaxanthin. These enzymatic steps were assigned after disruption of each ORF by a specific mutation and analysis of the accumulated intermediates. Carotenoid intermediates were identified by the absorption spectra of the colored components and by high pressure liquid chromatographic analysis. The six carotenoid genes are arranged in at least two operons. The gene coding for β-carotene hydroxylase is transcribed in the opposite direction from that of the other carotenoid genes and overlaps with the gene for phytoene synthase.     

Mechanistic deductions from kinetic isotope effects and pH studies of pyridoxal phosphate dependent carbon-carbon lyases: Erwinia herbicola and Citrobacter freundii tyrosine phenol-lyase

The pH dependence of the kinetic parameters and primary deuterium isotope effects have been determined for tyrosine phenol-lyase from both Erwinia herbicola and Citrobacter freundii. The primary deuterium isotope effects indicate that proton abstraction from the 2-position of the substrate is partially rate-limiting for both enzymes. The C. freundii enzyme primary deuterium isotope effects [DV = 3.5 and D(V/Ktyr) = 2.5] are pH independent, indicating that tyrosine is not sticky (i.e., does not dissociate slower than it reacts to give products). Since Vmax for both tyrosine and the alternate substrate S-methyl-L-cysteine is also pH independent, substrate binds only to the correctly protonated form of the enzyme. For the E. herbicola enzyme, both Vmax and V/K for tyrosine or S-methyl-L-cysteine are pH dependent, as well as both DV and D(V/Ktyr). Thus, while both the protonated and unprotonated enzyme can bind substrate, and may be interconverted directly, only the unprotonated Michaelis complex is catalytically competent. At pH 9.5, DV = 2.5 and D(V/Ktyr) = 1.5. However, at pH 6.4 the isotope effect on both parameters is equal to 4.1. From these data, the forward commitment factor (cf = 5.2) and catalytic ratio (cvf = 1.1) for tyrosine and S-methyl-L-cysteine (cf = 2.2, cvf = 24) are calculated. Also, the Michaelis complex partition ratio (cf/cvf) for substrate and products is calculated to be 4.7 for tyrosine and 0.1 for S-methyl-L-cysteine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cloning and nucleotide sequence of the bglA gene from Erwinia herbicola and expression of β-glucosidase activity in Escherichia coli

Abstract Genomic DNA fragments encoding β-glucosidase activity from the wild-type strain WD4 of Erwinia herbicola were cloned into Escherichia coli . Two clones containing a common fragment encoded a polypeptide of 58000 Da. Cloned β-glucosidase, expressed in E. coli , showed activity against natural β-glucoside sugars except for cellobiose. An open reading frame of 1442 bp termed bglA was identified by nucleotide sequencing and it coded for a protein of 480 amino acids ( M _r 53896) which showed significant homology with β-glucosidases from glycosyl hydrolase family 1.     

Physical characterization of the cloned protease III gene from Escherichia coli K-12.

Analysis of the cloned protease III gene (ptr) from Escherichia coli K-12 has demonstrated that in addition to the previously characterized 110,000-Mr protease III protein, a second 50,000-Mr polypeptide (p50) is derived from the amino-terminal end of the coding sequence. The p50 polypeptide is found predominantly in the periplasmic space along with protease III, but does not proteolytically degrade insulin, a substrate for protease III. p50 does not appear to originate from autolysis of the larger protein. Protease III is not essential for normal cell growth since deletion of the structural gene causes no observed alterations in the phenotypic properties of the bacteria. A 30-fold overproduction of protease III does not affect cell viability. A simple new purification method for protease III is described.     

Influence of gyrA mutation on expression of Erwinia chrysanthemi clb genes cloned in Escherichia coli.

Erwinia chrysanthemi clb genes cloned into Nals Escherichia coli allowed growth on cellobiose, arbutin, or salicin. In contrast, Nalr isogenic strains grew only on cellobiose. It is proposed that expression of cloned E. chrysanthemi clb genes is reduced by the E. coli chromosomal gyrA (Nalr) mutation, resulting in apparent segregation of the Clb and Arb Sal characters.     

Expression of pyruvate formate-lyase of Escherichia coli from the cloned structural gene

It is shown here that a plasmid (p29) derived from the transducing phage aspC2 (Christiansen and Pedersen 1981) codes for pyruvate formate-lyase. The identity of the 80 kilodaltons (kd) gene product of plasmid p29 with the pyruvate formate-lyase polypeptide was proven (i) by comigration of the gene product expressed in the maxicell system with purified enzyme on O'Farrell gels, and (ii) by comparison of the peptide maps obtained from limited proteolysis. In vivo the 80 kd form of the enzyme was proteolytically converted to a 78 kd polypeptide. The two polypeptides (80 kd and 78 kd) and their charge isomers present in purified enzyme preparations are therefore products of a single gene.Aerobically grown cells of Escherichia coli contained a basal level of pyruvate formate-lyase which was derepressed 5-to 10-fold under anaerobiosis. Derepression also occurred during anaerobic growth on glycerol plus fumarate. Presence of plasmid p29 caused overproduction of pyruvate formatelyase, 11-fold upon anaerobic growth on glucose, 14-fold upon aerobic growth on glucose and 33-fold upon aerobic growth at the expense of D-lactate.Non-Standard Abbreviation MOPS 4-morpholine-propane sulfonic     

Cloning and expression of the Erwinia chrysanthemi asparaginase gene in Escherichia coli and Erwinia carotovora

A genomic library of Erwinia chrysanthemi DNA was constructed in bacteriophage lambda 1059 and recombinants expressing Er. chrysanthemi asparaginase detected using purified anti-asparaginase IgG. The gene was subcloned on a 4.7 kb EcoRI DNA restriction fragment into pUC9 to generate the recombinant plasmid pASN30. The position and orientation of the asparaginase structural gene was determined by subcloning. The enzyme was produced at high levels in Escherichia coli (5% of soluble protein) and was shown to be exported to the periplasmic space. Purified asparaginase from E. coli cells carrying pASN30 was indistinguishable from the Erwinia enzyme on the basis of specific activity [660-700 units (mg protein)-1], pI value (8.5), and subunit molecular weight (32 X 10(3]. Expression of the cloned gene was subject to glucose repression in E. coli but was not significantly repressed by glycerol. Recombinant plasmids, containing the asparaginase gene, when introduced into Erwinia carotovora, caused increased synthesis of the enzyme (2-4 fold higher than the current production strain).     

Cloning and expression of pectin lyase gene from Erwinia carotovora in Escherichia coli

A pectin lyase (PNL; EC 4.2.2.10) gene of Erwinia carotovora Er was cloned and expressed in Escherichia coli. The analysis of the nucleotide sequence of the 0.6 kb StuI-EcoRI fragment, which was hybridized with the mixed oligonucleotide probe for PNL gene, revealed the presence of an open reading frame (0RF) and correlated exactly with the known N-terminal 18 amino acid sequence of PNL. When a plasmid pTN2159, which has a BamHI-EcoRI fragment containing this ORF, was introduced into E. coli JM109, PNL was not expressed. When a tac-promoter was inserted in front of the ORF, PNL was efficiently expressed in E. coli. Synthesis of PNL by E. coli was also confirmed by immunoblot analysis.     

Functional analysis of the Erwinia herbicola tutB gene and its product

The tutB gene, which lies just downstream of tpl, has been cloned from Erwinia herbicola, and its product was analyzed. Despite its high sequence similarity to tryptophan transporters, TutB was found to be a tyrosine-specific transporter. Tryptophan acted as a competitive inhibitor of tyrosine transport. Unlike the tryptophanase operon, the tpl and tutB genes do not constitute an operon.     

Purification and characterization of Escherichia coli endonuclease III from the cloned nth gene

The gene which codes for endonuclease III of Escherichia coli has been sequenced. The nth gene was previously subcloned and defined as the gene which led to overproduction of endonuclease III when present on a multicopy plasmid and which created a deficiency in endonuclease III activity when mutated. The nth gene was sequenced and translated into a predicted polypeptide. The molecular weight (23,546), the amino-terminal amino acid sequence, and the amino acid composition of the polypeptide predicted from the nucleotide sequence are excellent agreement with those same properties determined for the purified protein. Thus, the nth gene is the structural gene for endonuclease III. Inspection of the nucleotide sequence reveals that there is an open reading frame immediately upstream of the nth gene, suggesting that it might be part of an operon. There is a region of dyad symmetry which could form a hairpin stem and loop structure if transcribed into RNA characteristic of a rho-dependent terminator downstream from the nth gene. The nth gene of Escherichia coli has been cloned onto a lambda PL expression vector which yields approximately 300-fold overproduction of endonuclease III. We have purified the enzyme to apparent homogeneity using two chromatographic steps. Our purification scheme allowed the preparation of 117 mg of protein from 190 g of E. coli with a 70% yield. The purified protein has both AP endonuclease activity and DNA N-glycosylase activity. The protein has a Stokes radius of 2.25 nm, a sedimentation coefficient of 2.65 S, a molecular weight of 26,300 in the native state and 27,300 in the denatured state, and a frictional ratio of 1.13.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of expression of the cloned ada gene in Escherichia coli

The ada gene of Escherichia coli K12, the regulatory gene for the adaptive response of bacteria to alkylating agents, was cloned in multicopy plasmids. O6-Methylguanine-DNA methyltransferase and 3-methyladenine-DNA glycosylase II, which are known to be inducible as part of the adaptive response, were produced in ada- cells bearing ada+ plasmids, even without treatment with alkylating agents. When such cells had been treated with methyl methanesulfonate, even higher levels of the enzyme activities were produced. Maxicell experiments revealed that the ada gene codes for a polypeptide with a molecular weight of 38 000. We constructed a hybrid plasmid carrying an ada'-lacZ' fused gene, with the proper control region for ada expression. beta-Galactosidase synthesis from the fused gene was strongly induced only when cells were treated with low doses of methylating agents, but was weakly induced with relatively high doses of ethylating agents. The induction was autogenously regulated by the ada gene product, in a positive manner.