Levels Of Histidase Research Articles

Activation of the Bacillus subtilis hut operon at the onset of stationary growth phase in nutrient sporulation medium results primarily from the relief of amino acid repression of histidine transport

During growth of Bacillus subtilis in nutrient sporulation medium containing histidine (DSM-His medium), the expression of histidase, the first enzyme in the histidine-degradative pathway (hut), is derepressed 40- to 200-fold at the onset of stationary phase. To identify the gene products responsible for this regulation, histidase expression was examined in various hut regulatory mutants as well as in mutants defective in stationary-phase gene regulation. Histidase expression during growth in DSM-His medium was significantly altered only in a strain containing the hutC1 mutation. The hutC1 mutation allows the hut operon to be expressed in the absence of its inducer, histidine. During logarithmic growth in DSM-His medium, histidase levels were 25-fold higher in the HutC mutant than in wild-type cells. Moreover, histidase expression in the HutC mutant increased only four- to eightfold after the end of exponential growth in DSM-His medium. This suggests that histidine transport is reduced in wild-type cells during exponential growth in DSM-His medium and that this reduction is largely responsible for the repression of hut expression in cells growing logarithmically in this medium. Indeed, the rate of histidine uptake in DSM-His medium was fourfold lower in exponentially growing cells than in stationary-phase cells. The observation that the degradation of histidine is inhibited when B. subtilis is growing rapidly in medium containing a mixture of amino acids suggests that a hierarchy of amino acid utilization may be present in this bacterium.

Effect of Hormones and Protein Level on Induction of Enzymes Involved in Histidine Degradation and Folate Metabolism

Summary The effects of the hormones thyroxine, glucagon and hydrocortisone, and of protein level on hepatic histidase, urocanase, and certain folate enzymes were studied in rats. Hypothyroidism, induced either by feeding thiouracil or by thyroidectomy, increased histidase, urocanase, and the folate dependent enzyme formiminotransferase, and increased histidine metabolism as measured by oxidation of the 2-ring carbon of histidine to carbon dioxide. Hyperthyroidism, produced by feeding thyroid powder, decreased histidine oxidation and liver levels of this enzyme. Glucagon and hydrocortisone increased histidine oxidation and increased levels of histidase, urocanase and formiminotransferase. Elevated levels of casein and soy protein produced four to eight fold increases in histidase and urocanase, and 50% increases in formiminotransferase. Thus, increases in histidase and urocanase involved in the formation of formiminoglutamic acid (FIGlu) were accompanied by increases in the FIGlu metabolizing enzyme formiminotransferase.

Polarity in the glnA operon: suppression of the reg- phenotype by rho mutations.

To determine the ability of mutations in glnA, the gene for glutamine synthetase (GS), to regulate nitrogen assimilatory enzymes, we assayed histidase and GS in 34 glnA (Gln(-)) strains. Twenty-five glnA mutants were RegC, synthesizing high levels of histidase regardless of the availability of nitrogen, and nine were Reg(-), synthesizing low levels of histidase in medium containing either limiting or excess ammonia. rho mutations were introduced into strains containing glnA point mutations or insertions in glnA, glnL, glnG, or glnF. The Reg(-) phenotype of strains with glnA point mutations, but not those with glnA or glnF insertions, was altered by the presence of rho, suggesting that glnA (Reg(-)) mutations are polar and exert their phenotype by decreasing expression of glnL and glnG. Consistent with this view, no GS protein was detected by two-dimensional gel electrophoresis in glnA (Reg(-)) rho(+) or glnA (Reg(-)) rho double mutants, whereas GS protein was detected in cells of 10 of 11 glnA (RegC) strains. Since glnA (Reg(-)) rho double mutants synthesize constitutive levels of histidase, GS protein is not necessary for full expression of histidase. Mu d1 insertions in glnL, but not those in glnG, responded to the presence of a rho allele, presumably owing to elevated transcription into glnG from the Mu d1 prophage. Our results suggest that glnA (Reg(-)) alleles are polar mutations, and a rho-dependent termination site down-stream is postulated as the basis for the polar phenomenon. The data also indicate that, under some circumstances, a significant portion of glnL and glnG transcription is initiated at the glnA promoter.

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.

Mutants affecting histidine utilization in Aspergillus nidulans.

SUMMARYWild-type strains ofAspergillus nidulansgrow poorly onL-histidine as a sole nitrogen source. The synthesis of the enzyme histidase (EC. 4.3.1.3) appears to be a limiting factor in the growth of the wild type, as strains carrying the mutantareA102 allele have elevated histidase levels and grow strongly on histidine as a sole nitrogen source.L-Histidine is an extremely weak sole carbon source for all strains.Ammonium repression has an important role in the regulation of histidase synthesis and the relief of ammonium repression is dependent on the availability of a good carbon source. The level of histidase synthesis does not respond to the addition of exogenous substrate.Mutants carrying lesions in thesarA orsarB loci (suppressor ofareA102) have been isolated. The growth properties of these mutants on histidine as a sole nitrogen source correlate with the levels of histidase synthesized. Mutation at thesarA andsarB loci also reduces the utilization of a number of other nitrogen sources. The data suggest that these two genes may code for regulatory products involved in nitrogen catabolism. No histidase structural gene mutants were identified and possible explanations of this are discussed.

Histidinaemia in mouse and man.

A recently discovered mutant in the mouse was found to have very low levels of histidase. It is an autosomal recessive. In its enzymic and metabolic properties it appears to be a homologue of human histidinaemia. While the homozygous mouse mutants show no overt abnormalities, offspring of histidinaemic mothers display a balance defect resulting in circling behaviour. This is associated with vestibular damage during in utero development. Mental retardation caused by human maternal phenylketonuria may have a similar aetiology.

A lipotrope-dependent increase of histidase and urocanase in the livers of choline-deficient rats and in the reuber H-35 transplanted hepatoma

The administration of choline to choline-deficient rats led to significant increases in the hepatic levels of histidase ( l-histidine ammonia-lyase, EC 4.3.1.3) and urocanase (4-imidazolone-5-propionate hydro-lyase, EC 4.2.1.49). In contrast high dietary levels of methionine and choline had no significant effect on the levels of histidase and urocanase in the livers of chow-fed rats. Similarly, high dietary levels of methionine, choline and vitamin B 12, either alone or in combination, did not alter the levels of histidase and urocanase in the livers of rats bearing the Reuber H-35 transplantated hepatoma. However, a chow diet containing elevated levels of methionine, choline and vitamin B 12 led to marked increases in the activities of both histidase and urocanase in the H-35 hepatoma. These results indicate that the altered control of histidase and urocanase seen in hepatomas may result from the abnormal metabolism of methyl donors generally seen in tumors.

Histidinaemia. Study of relation between clinical and biological findings in 7 subjects.

Seven subjects with raised plasma histidine and low skin histidase levels (histidinaemia) are described: 4 were severely retarded, 2 showing in addition features of an early infantile psychosis (autism); 3 were of normal intelligence. There were no biochemical differences between the two groups. In view of these findings and a study of patients reported in the literature, attention is drawn to the difficulty in making a decision about treatment of a neonate detected by screening and shown to have the biochemical features of histidinaemia. The natural history of the condition is further examined, particularly the question of deterioration at time of seizures or infection.

Hormonal Influences on Hepatic Histidase

Journal Article Hormonal Influences on Hepatic Histidase Get access NEAL W. CORNELL, NEAL W. CORNELL *Chemistry Department, Pomona College Claremont, California 91711;Department of Obstetrics and Gynecology, University of Pittsburgh Pittsburgh, Pennsylvania 15213 Search for other works by this author on: Oxford Academic Google Scholar JOHN B. JOSIMOVICH, JOHN B. JOSIMOVICH *Chemistry Department, Pomona College Claremont, California 91711;Department of Obstetrics and Gynecology, University of Pittsburgh Pittsburgh, Pennsylvania 15213 Search for other works by this author on: Oxford Academic Google Scholar LINDA L. LIEN, LINDA L. LIEN *Chemistry Department, Pomona College Claremont, California 91711;Department of Obstetrics and Gynecology, University of Pittsburgh Pittsburgh, Pennsylvania 15213 Search for other works by this author on: Oxford Academic Google Scholar KOWETHA A. DAVIDSON KOWETHA A. DAVIDSON *Chemistry Department, Pomona College Claremont, California 91711;Department of Obstetrics and Gynecology, University of Pittsburgh Pittsburgh, Pennsylvania 15213 Search for other works by this author on: Oxford Academic Google Scholar Endocrinology, Volume 88, Issue 2, 1 February 1971, Pages 507–511, https://doi.org/10.1210/endo-88-2-507 Published: 01 February 1971 Article history Received: 13 May 1970 Published: 01 February 1971

Histidase and urocanase activities of liver and plasma. Correlations between tissue enzyme levels and plasmatic increases during human and mouse viral hepatitis

In human liver it is clearly evident that the levels of histidase and urocanase activities are considerably lower than those encountered in mouse liver. Both in the mouse and in the man urocanase presents levels of activity much higher than histidase. The apparent K m of histidine for the mouse histidase was 2.71 · 10 −4 M, whereas the K m for the human histidase was 4.83 · 10 −4 M; the apparent K m value of urocanase was 2.18· 10 −6 M for man, and 3.19sd 10 −3 M for the mouse. In mouse hepatitis there is a decrease of both enzyme activities in the liver and at the same time their passage in blood is observed. In human viral hepatitis the levels of both enzymes in blood plasma increase in an inconstant manner and no relationship can be observed with the extent of the hepatocellular damage.