Genetic control of tyramine oxidase, which is involved in derepressed synthesis of arylsulfatase in Klebsiella aerogenes.

Mutants of Klebsiella aerogenes with three types of mutations affecting regulation of tyramine oxidase were isolated by a simple selection method. In the first type, the mutation (tynP) was closely linked to the structural gene for tyramine oxidase tynA). The order of mutation sites was atsA-tynP-tynA. In the second type, the mutation that relieves catabolite repression of the syntheses of several catabolite repression-sensitive enzymes are not linked to the tyn gene by P1 transduction. These strains contained high levels of cyclic adenosine 5'-monophosphate when grown on glucose. The third type of mutation, in which tyramine oxidase was synthesized constitutively, was shown by genetic analysis to involve mutations of tynP and tynR. The tynR gene was not linked to tynA. Results using the constitutive mutants showed that the constitutive expression of the tynA gene resulted in depression of arylsulfatase synthesis in the absence of tyramine.     

Tyramine oxidase and regulation of arylsulfatase synthesis in Klebsiella aerogenes.

The participation of tyramine oxidase in the regulation of arylsulfatase synthesis in Klebsiella aerogenes was studied. Arylsulfatase was synthesized when this organism was grown with methionine or taurine as the sulfur source (nonrepressing conditions) and was repressed by inorganic sulfate or cysteine; this repression was relieved by tyramine and related compounds (derepressing conditions). Under nonrepressing conditions, arylsulfatase synthesis was not regulated by tyramine oxidase synthesis. However, derepression of arylsulfatase and induction of tyramine oxidase synthesis by tyramine were both antagonized by glucose and other carbohydrate compounds. The derepressed synthesis of arylsulfatase, like that of tyramine oxidase, was released from catabolite repression by use of tyramine as the sole source of nitrogen. A mutant strain that exhibits constitutive synthesis of glutamine synthetase and high levels of histidase when grown in glucose-ammonium medium was subject to the catabolite repression of both tyramine oxidase and arylsulfatase syntheses. Mutants in which repression of arylsulfatase could not be relieved by tyramine could not utilize tyramine as the sole source of nitrogen and were defective in the gene for tyramine oxidase.     

Regulation of derepressed synthesis of arylsulfatase by tyramine oxidase in Salmonella typhimurium.

The participation of tyramine oxidase in the regulation of arylsulfatase synthesis in Salmonella typhimurium was studied. Arylsulfatase synthesis was repressed by inorganic sulfate, cysteine, methionine, or taurine. This repression was relieved by tyramine, octopamine, or dopamine, which induced tyramine oxidase synthesis, although the level of arylsulfatase activity was very low. The induction of tyramine oxidase and derepression of arylsulfatase by tyramine were strongly inhibited by glucose and ammonium chloride, and the repression of both enzymes was relieved by use of xylose as a carbon source after consumption of glucose or by use of tyramine as the sole source of nitrogen, irrespective of the carbon source used. The initial rates of tyramine uptake by cells grown with glucose and xylose were similar. Results with tyramine oxidase-constitutive mutants showed that constitutive expression of the tyramine oxidase gene resulted in derepression of arylsulfatase synthesis in the absence of tyramine. Thus, catabolite and ammonium repressions of arylsulfatase synthesis and the induction of the enzyme by tyramine seem to reflect the levels of tyramine oxidase synthesis. These results in S. typhimurium support our previous finding that the specific regulation system of arylsulfatase synthesis by tyramine oxidase is conserved in enteric bacteria.     

Quantitative Analysis of the Sex Pheromone of Several Phycitid Moths by Electron-capture Gas Chromatography

β-Phenetyl alcohol and procaine hydrochloride are known to alter membrane structure. Their effects on the syntheses of tyramine oxidase and arylsulfatase were studied in Klebsiella aerogenes. β-Phenetyl alcohol inhibited the syntheses of membrane-bound tyramine oxidase and arylsulfatase, located in the periplasm, under non-repressing and derepressing conditions, but did not affect the syntheses of β-galactosidase and histidase, which are located internally. In contrast, procaine hydrochloride stimulated the synthesis of tyramine oxidase and derepressed the synthesis of arylsulfatase, but inhibited non-repressed synthesis of arylsulfatase. Thus, derepressed synthesis of cellular arylsulfatase was affected by the level of tyramine oxidase synthesis. Structural alterations in the cell membrane seem to impair the formation of active-arylsulfatase protein in the periplasmic space.     

Use of lac Gene Fusions to Study Regulation of Tyramine Oxidase,Which is Involved in Derepression of Latent Arylsulfatase in Escherichia coli

Strains with lac fused to each of the arylsulfatase (ats) and tyramine oxidase (tyn) operons in Escherichia coli were isolated. Synthesis of β-galactosidase in strains with tyn:: lac fusions was induced by tyramine, histamine, tryptamine, dopamine and octopamine, and the induction of the tyn operon was subject to catabolite and ammonium repressions. These repressions were relieved when the cells were grown with a poor carbon or nitrogen source. No arylsulfatase activity is detected in E. coli strains. Synthesis of β-galactosidase in strains with ats:: lac fusions was repressed by sulfur compounds. The repression was relieved by monoamine compounds, which induced tyramine oxidase synthesis. The inhibition of tyramine oxidase activity by cysteine resulted in a decrease of the derepressed synthesis of β-galactosidase in the ats:: lac fusion. Repressing and derepressing conditions for the tyn operon prevented and stimulated, respectively, expression of the ats operon. Thus, the expression of latent arylsulfatase in E. coli seems to be regulated by expression of the tyn operon.     

Genetic control of arylsulfatase synthesis in Klebsiella aerogenes.

It was shown that at least four genes are specifically responsible for arylsulfatase synthesis in Klebsiella aerogenes. Mutations at chromosome site atsA result in enzymatically inactive arylsulfatase. Mutants showing constitutive synthesis of arylsulfatase (atsR) were isolated by using inorganic sulfate or cysteine as the sulfur source. Another mutation in which repression of arylsulfatase by inorganic sulfate or cysteine could not be relieved by tyramine was determined by genetic analysis to be on the tyramine oxidase gene (tyn). This site was distinguished from the atsC mutation site, which is probably concerned with the action or synthesis of corepressors of arylsulfatase synthesis. Genetic analysis with transducing phage PW52 showed that the order of mutation sites was atsC-atsR-atsA-tynA-tynB. On the basis of these results and previous physiological findings, we propose a new model for regulation of arylsulfatase synthesis.     

Negative control of the galactose operon in E. coli

Summary Non-inducible mutants have been isolated which synthesize the three galactose enzymes with the basal rate both in the absence and in the presence of inducers. These mutations are closely linked to the lysA gene, as are the constitutive mutations in the regulator gene first described by Buttin (1963).The non-inducible mutants are Gal ^– on EMB gal plates. Revertants to the Gal ⁺ phenotpye are constitutive. Heterozygotes have been prepared at the locus of the regulator gene (galR), abd dominance studies involving the different alleles at this locus have been carried out. The non-inducible mutations are dominant over the wildtype, and this in turn is dominant over constitutive mutations in the galR gene.Starting from the non-inducible mutations, deletions have been isolated, which extend from the galR gene into the lysA gene. These are constitutive.The behavior of the non-inducible mutations and of the deletions are strong arguments for negative control of the galactose operon.     

Catabolite repression and derepression of arylsulfatase synthesis in Klebsiella aerogenes

When a mutant (Mao(-)) of Klebsiella aerogenes lacking an enzyme for tyramine degradation (monoamine oxidase) was grown with d-xylose as a carbon source, arylsulfatase was repressed by inorganic sulfate and repression was relieved by tyramine. When the cells were grown on glucose, tyramine failed to derepress the arylsulfatase synthesis. When grown with methionine as the sole sulfur source, the enzyme was synthesized irrespective of the carbon source used. Addition of cyclic adenosine monophosphate overcame the catabolite repression of synthesis of the derepressed enzyme caused by tyramine. Uptake of tyramine was not affected by the carbon source. We isolated a mutant strain in which derepression of arylsulfatase synthesis by tyramine occurred even in the presence of glucose and inorganic sulfate. This strain also produced beta-galactosidase in the presence of an inducer and glucose. These results, and those on other mutant strains in which tyramine cannot derepress enzyme synthesis, strongly suggest that a protein factor regulated by catabolite repression is involved in the derepression of arylsulfatase synthesis by tyramine.     

Immunological Studies on Antisera of Mice Immunized with Dried or DEPC-treated Ehrlich Ascites Tumor Cells

Intracellular arylsulfatases from Klebsiella aerogenes W70 cells grown in methionine medium (M enzyme) and inorganic sulfate medium containing tyramine (T enzyme) were purified respectively by fractionation with (NH₄)₂SO₄, followed by successive chromatographies on DEAE cellulose, hydroxylapatite, Sephadex G-100 and DEAE Sephadex A-25. On polyacrylamide gel electrophoresis, the two enzymes gave single bands with the same mobilities. Molecular weights of both, determined by SDS gel electrophoresis and by Sephadex G-100 chromatography, were 47,000 and 45,000, respectively. Their activities were maximal at pH 7.5. The affinities of the enzymes (M and T enzymes) for their substrate (Km) and the maximum velocity of hydrolysis (V_max) were enhanced by addition of electron withdrawing substituents. The enzymes were inhibited by inorganic phosphate, cyanide, hydroxylamine and tyramine. The inhibition by tyramine was competitive (Ki = 1.0 × 10^?4 m). These results show that the two enzymes were identical. This was confirmed by the fact that mutant strains, which were unable to synthesize arylsulfatase when grown with methionine, could also not synthesize the enzyme when grown with tyramine.     

Studies of monoamine oxidases: properties of the enzyme in bovine and rabbit brain mitochondria

Brain mitochondria were prepared from rabbit and bovine cerebral cortex and the purity and intactness of the preparation assessed through the use of enzyme markers and electron microscopy. Enzymatic properties of monoamine oxidase were studied in the purified mitochondrial preparations which were essentially devoid of major contamination by other organelles, especially microsomes. Five substrates were used for characterization of the enzyme: dopamine, kynuramine, serotonin, tryptamine and tyramine. It was found that there was considerable substrate variation in the properties, but in general, the two species showed similar characteristics. The more pertinent findings were: (1) apparent K_m values ranged from 1.1 ± 10^?5m for tryptamine to 2.5 ± 10^?4m for dopamine; (2) substrate specificity from V_max values in decreasing order was tyramine > dopamine > kynuramine > serotonin > tryptamine for the bovine enzyme and tyramine > kynuramine > dopamine > serotonin > tryptamine for rabbit; (3) there appeared to be three distinct pH optima according to substrate: pH 7.5 for phenylethylamines, pH 8.2–8.5 for the indolylamines and pH 9.1 for kynuramine; and (4) the activity with tyramine was highly sensitive to increased oxygen tension while kynuramine showed no sensitivity. It is proposed that the properties of monoamine oxidase, a membrane-bound enzyme, might be influenced by the microenvironment and results are also discussed in terms of multiple forms or multiple activity sites on a single form.     

Genetic mapping of tyramine oxidase and arylsulfatase genes and their regulation in intergeneric hybrids of enteric bacteria.

The genes for arylsulfatase (atsA) and tyramine oxidase (tynA) have been mapped in Klebsiella aerogenes by P1 transduction. They are linked to gdhD and trp in the order atsA-tynA-gdhD-trp-pyrF. Complementation analysis using F' episomes from Escherichia coli suggested an analogous location of these genes in E. coli, although arylsulfatase activity was not detected in E. coli. P1 phage and F' episomes were used to create intergeneric hybrid strains of enteric bacteria by transfer of the ats and tyn genes between K. aerogenes, E. coli, and Salmonella typhimurium. Intergeneric transduction of the tynK gene from K. aerogenes to an E. coli restrictionless strain was one to two orders less frequent than that of the leuK gene. The tyramine oxidase of E. coli and S. typhimurium in regulatory activity resemble very closely the enzyme of K. aerogenes. The atsE gene from E. coli was expressed, and latent arylsulfatase protein was formed in K. aerogenes and S typhimurium. The results of tyramine oxidase and arylsulfatase synthesis in intergeneric hybrids of enteric bacteria suggest that the system for regulation of enzyme synthesis is conserved more than the structure or function of enzyme protein during evolution.     

Immunological study of the regulation of cellular arylsulfatase synthesis in Klebsiella aerogenes.

Regulation of cellular arylsulfatase synthesis in Klebsiella aerogenes was analyzed by immunological techniques. Antibody directed against the purified arylsulfatase from K. aerogenes W70 was obtained from rabbits and characterized by immunoelectrophoresis, double-diffusion, quantitative precipitation, and enzyme neutralization tests. Arylsulfatase was located in the periplasmic space when the wild-type strain was cultured with methionine or with inorganic sulfate plus tyramine, but not with inorganic sulfate without tyramine, as the sole sulfur source. Tyramine oxidase was retained in the membrane fraction prepared from cells grown in the presence of tyramine. Arylsulfatase protein was not synthesized in the presence of tyramine and inorganic sulfate by mutant K611, which is deficient in tyramine oxidase (tynA). We conclude that the expression of the arylsulfatase gene (atsA) is regulated by the expression of tynA and that inorganic sulfate serves as a corepressor. In addition, strains mutated in the atsA gene were analyzed by using antibody.     

Genetic analysis of instability in Petunia hybrida

Summary In crossing experiments with Petunia hybrida, new mutations, some unstable, have been found in descendants of plants having an unstable allele of the anthocyanin gene An1. One of the unstable mutations affecting the new anthocyanin gene An11 was genetically analyzed, and it was subsequently established in which step of anthocyanin synthesis that An11 is involved. The discovery of new, unstable mutations at other loci indicates that in Petunia also a relation exists between unstable mutations and the presence of transposable elements in the genome. It was demonstrated that reverted alleles (an1 ^+/+) originating from unstable An1 alleles are less stable than the original wild-type allele An1, and that reversions do not increase the chances of occurrence of new, stable or unstable mutations at other loci. These results provide additional arguments in favour of the hypothesis posed in an earlier paper that reversions of unstable An1 alleles are not the result of excision of the inserted transposable element, but are due to the repair of secondary mutations induced by the insert in the regulatory region of the locus. Consequently, a reverted allele still contains the inserted element that may again induce mutations leading to inactivation of An1.     

Insertion mutations in the control region of the Gal operon of E. coli. I. Biological characterization of the mutations

Summary Galactose negative mutations are described which reduce the maximum expression of all three gal genes about 100-fold. The residual enzyme synthesis is not or only slightly inducible.These pleiotropic mutations map in the control region of the gal operon. No recombination is observed between these mutations. All mutants revert spontaneously to a Gal⁺ phenotype. In some mutations wildtype-like as well as constitutive revertants are obtained. The frequency of reversion can be increased by nitrosoguanidine (NG) in all mutants. The revertants, induced by this mutagen, are of a constitutive type.     

Mutations in the galactose-operator

Summary Constitutive mutations in the galactose operator in E. coli arise with a frequency ten times smaller than in the regulator gene. The operator constitutive mutations do not arise as a consequence of mutagen treatment.Operator constitutive mutations do not revert to wildtype spontaneously or after mutagen treatment.It is concluded that operator constitutive mutations are multisite mutations, and that the operator region is considerably smaller than the regulator gene in the gal operon.     

Control of lysogenization by phage P22 I. The P22 cro gene

P22 cro^? mutants were isolated as one class of phage P22 mutants (cly mutants) that have a very high frequeney of lysogeny relative to wild-type P22. These mutants: (1) do not form plaques and over-lysogenize relative to wild-type P22 after infection of a wild-type Salmonella host; (2) are defective in anti-immunity; and (3) fail to turn off high-level synthesis of P22 c2-repressor after infection.P22 cro^? mutations are recessive and map between the P22 c2 and c1 genes. P22 cro^? mutations are suppressed by clear-plaque mutations in the c1 gene, one of which is simultaneously cy^?. They are also suppressed, but incompletely, by mutations in the c2 (repressor) gene, especially those that do not completely abolish c2 gene function.Salmonella host mutants have been isolated that are permissive for the lytic growth of the P22 cro^? mutants.     

Arsenite oxidation by a facultative chemolithoautotrophic Sinorhizobium sp. KGO-5 isolated from arsenic-contaminated soil

A chemolithoautotrophic arsenite-oxidizing bacterium, designated strain KGO-5, was isolated from arsenic-contaminated industrial soil. Strain KGO-5 was phylogenetically closely related with Sinorhizobium meliloti with 16S rRNA gene similarity of more than 99%, and oxidized 5?mM arsenite under autotrophic condition within 60?h with a doubling time of 3.0?h. Additions of 0.01–0.1% yeast extract enhanced the growth significantly, and the strain still oxidized arsenite efficiently with much lower doubling times of approximately 1.0?h. Arsenite-oxidizing capacities (11.2–54.1?μmol?h^?1?mg dry cells^?1) as well as arsenite oxidase (Aio) activities (1.76–10.0?mU?mg protein^?1) were found in the cells grown with arsenite, but neither could be detected in the cells grown without arsenite. Strain KGO-5 possessed putative aioA gene, which is closely related with AioA of Ensifer adhaerens. These results suggest that strain KGO-5 is a facultative chemolithoautotrophic arsenite oxidizer, and its Aio is induced by arsenic.     

A gene required for nuclear and mitochondrial attachment in the nematode caenorhabditis elegans

Nuclei occupy characteristic positions in most cells. In Caenorhabditis elegans, nuclei can be observed in living animals. Ordinary movements can distort the cells and displace their nuclei, but the extent of displacement is limited and nuclei return to their resting positions when the muscles relax. We have isolated five mutants in which the nuclei of certain epithelial cells are not elastically anchored but float freely within the cytoplasm. These mutations define a single gene, anc1, on linkage group I. Mitochondrial positioning, observed by staining live animals with rhodamine 6G, is also disturbed in these cells. Additional defects, including abnormal tonofilaments and inappropriately positioned desmosomes, have been found by electron microscopy. The anc1 product may be a cytoskeletal component of nematode epithelial cells. Although the Anc1 phenotype is fully expressed in the newly hatched larvae, mutants develop and reproduce normally. Despite mispositioning of organelles, cuticle deposition and moulting are essentially normal. These mutations represent the null phenotype of the gene. At least three independent isolates revert spontaneously at high frequency (10^?5 to 10^?4). We suggest that anc1 is a member of a family of cytoskeletal genes.     

Mutations affecting the reduced nicotinamide adenine dinucleotide dehydrogenase complex of Escherichia coli

A strain carrying a point mutation affecting the NADH dehydrogenase complex of Escherichia coli has been isolated and its properties examined. The gene carrying the mutation (designated ndh) was located on the E. coli chromosome at about minute 23 and was shown to be cotransducible with the pyrC gene. Strains carrying the ndh^? allele were found to be unable to grow on mannitol and to grow very poorly on glucose unless the medium was supplemented with succinate, acetate or casamino acids.The following properties of strains carrying the ndh^? allele were established which suggest that the mutation affects the NADH dehydrogenase complex but apparently not the primary dehydrogenase. Membrane preparations possess normal to elevated levels of d-lactate oxidase and succinate oxidase activities but NADH oxidase is absent. NADH is unable to reduce ubiquinone in the aerobic steady state and reduces cytochrome b very slowly when the membranes become anaerobic. NADH dehydrogenase, measured as NADH-dichlorophenolindophenol reductase is reduced but not absent. NADH oxidase is stimulated by menadione although not by Q-3 or MK-1 and in the presence of menadione, cytochrome b is reduced normally by NADH.Further mutants affected in NADH oxidase were isolated using a screening procedure based on the growth characteristics of the original ndh^? strain. The mutations carried by these strains were all cotransducible with the pyrC gene and the biochemical properties of the additional mutants were similar to those of the original mutant.The properties of the group of ndh^? mutants established so far suggest that they are affected in the transfer of reducing equivalents from the NADH dehydrogenase complex to ubiquinone.