ON THE BIOSYNTHESIS OF PSEUDOURIDINE AND OF PSEUDOURIDYLIC ACID IN AGROBACTERIUM TUMEFACIENS

1966 ◽  
Vol 44 (2) ◽  
pp. 259-272 ◽  
Author(s):  
T. Suzuki ◽  
R. M. Hochster
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Biosynthetic Pathway ◽  
Direct Synthesis ◽  
Ion Concentration ◽  
Sodium Arsenate ◽  
Ph Optimum ◽  
Crude Extracts ◽  
Plant Tumor ◽  
Michaelis Constants

Crude extracts prepared from the plant tumor inducing organism Agrobacterium tumefaciens were shown to convert uracil and D-ribose-5-phosphate to pseudouridine in stoichiometric amounts. The addition of the nucleotidase inhibitor sodium arsenate altered the course of the reactions involved in such a way that pseudouridylic acid became the product. Under these conditions, the latter was formed in the same relative concentrations as pseudouridine in experiments without inhibitor.The direct synthesis of pseudouridylic acid from the above precursors was found to be catalyzed by an enzyme which has been tentatively designated as "pseudouridylic acid synthetase". This enzyme was separated from the nucleotidase and purified 80-fold. Parameters such as pH optimum, required ion concentration, and Michaelis constants were determined.The data presented in this paper permit the first description of the biosynthetic pathway for pseudouridylic acid and for pseudouridine in a bacterium.

Stimulation of α-glucosidases from fast-growing rhizobia and Agrobacterium tumefaciens by K+, NH+4, and Rb+

1990 ◽  
Vol 36 (3) ◽  
pp. 223-227 ◽  
Author(s):  
Inger Hoelzle ◽  
John G. Streeter
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Rhizobium Leguminosarum ◽  
Bacterial Species ◽  
Ion Concentration ◽  
Substrate Affinity ◽  
Experimental Conditions ◽  
Ph Optimum ◽  
Fast Growing ◽  
Fast Growing Rhizobia ◽  
Hydrolysis Of

Extracts from cultured fast-growing rhizobia and Agrobacterium tumefaciens contain enzymes for hydrolysis of the α-glucosides maltose, sucrose, and α,α-trehalose. The hydrolysis of all three sugars was stimulated by the presence of K+, Rb+, or [Formula: see text]. This stimulation varied from less than 2-fold to more than 12-fold, depending on the bacterial species, culture conditions, and experimental conditions, such as type of enzyme, buffer, and ion concentration. Eight other ions tested, including several divalent cations, did not have any stimulatory effect. Other sources of enzyme (Escherichia coli, Saccharomyces cerevisiae, Oryza sativa, porcine kidney, and Medicago sativa and Glycine max nodule cytosol) contained α-glucosidases that differed in both substrate specificity and pH optima and were not affected by K+, Rb+ or [Formula: see text] ions. Bacteroids from G. max and Phaseolus vulgaris nodules did not have detectable α-glucosidase activity. Growth of Rhizobium leguminosarum biovar phaseoli USDA 2667 with one of the α-glucosides as carbon source increased Vm and substrate affinity for all three disaccharidase activities. The pH optimum for all three enzyme activities in R. leguminosarum bv. phaseoli USDA 2667 was 6.6. Stimulation by specific monovalent cations appears to be a novel property of α-glucosidases in the bacterial family Rhizobiaceae. Key words: maltose, sucrose, trehalose, disaccharidases, Rhizobiaceae.

scholarly journals The diphosphoinositide kinase of rat brain

1968 ◽  
Vol 106 (4) ◽  
pp. 791-801 ◽  
Author(s):  
M. Kai ◽  
J. G. Salway ◽  
J. N. Hawthorne
Keyword(s):  
Rat Brain ◽  
Kinase Activity ◽  
Ion Concentration ◽  
Supernatant Fraction ◽  
Thiol Groups ◽  
Ph Optimum ◽  
Adult Rat ◽  
Phosphatidylinositol Kinase ◽  
Adult Rat Brain ◽  
Ammonium Sulphate Fractionation

1. The supernatant fraction of adult rat brain contains a diphosphoinositide kinase. 2. Formation of triphosphoinositide by the enzyme in the presence of ATP and Mg2+ ions was shown with labelled ATP or labelled diphosphoinositide. 3. The kinase was also activated by Ca2+, Mn2+ and Co2+ ions, but to a smaller extent than by Mg2+ ions. 4. In the presence of optimum Mg2+ ion concentration the enzyme was inhibited by Ca2+ ions. 5. Activity did not depend on thiol groups and the pH optimum was 7·3. 6. The dialysed supernatant fraction had no diglyceride kinase activity and negligible phosphatidylinositol kinase activity. 7. Triphosphoinositide phosphomonoesterase was present but showed little activity under the conditions used to assay the kinase. 8. Diphosphoinositide kinase was purified by ammonium sulphate fractionation, ethanol treatment and chromatography on Sephadex G-200. 9. This purification removed much of the triphosphoinositide phosphomonoesterase.

Phosphoenolpyruvate Carboxylase of Thiobacillus thiooxidans. Kinetic and Metabolic Control Properties

1972 ◽  
Vol 50 (2) ◽  
pp. 158-165 ◽  
Author(s):  
R. L. Howden ◽  
H. Lees ◽  
Isamu Suzuki
Keyword(s):  
Enzyme Activity ◽  
Competitive Inhibitor ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
Pep Carboxylase ◽  
Thiobacillus Thiooxidans ◽  
Powerful Activator ◽  
Michaelis Constants ◽  
Noncompetitive Inhibitor ◽  
Decreasing Ph

Phosphoenolpyruvate (PEP) carboxylase (orthophosphate:oxalacetate carboxy-lyase (phosphorylating), EC 4.1.1.31) was purified 19-fold from Thiobacillus thiooxidans. The level of enzyme activity was dependent on culture age. No enzyme activity could be obtained from frozen cells.The pH optimum of the enzyme was determined to be around 8.0. Apparent Michaelis constants were determined for the substrates:phosphoenolpyruvate (1.4, 1.5 mM), bicarbonate (0.4, 1.1 mM), and magnesium (1.1, 0.8 mM) at pH 7.0 and 8.0, respectively. Acetyl-CoA was found to be a powerful activator of this enzyme, with the degree of activation increasing with decreasing pH. The concentration of acetyl-CoA to obtain half-maximal activation, however, remained fairly constant and low, namely 1.2 and 1.0 μM at pH 7.0 and 8.0, respectively. L-Aspartate and L-malate were strong inhibitors of enzyme activity. In the presence of aspartate at pH 7.0 the double reciprocal activity plots for PEP became nonlinear, a characteristic of negative cooperativity. These plots became linear with the addition of acetyl-CoA with aspartate now acting as a noncompetitive inhibitor with respect to PEP. At pH 8.0, the same plots were linear with aspartate acting as a competitive inhibitor of PEP. All the other effectors of PEP carboxylase from Salmonella typhimurium and Escherichia coli were found to be ineffective towards the enzyme from T. thiooxidans.

scholarly journals Spermidine Inversely Influences Surface Interactions and Planktonic Growth in Agrobacterium tumefaciens

2016 ◽  
Vol 198 (19) ◽  
pp. 2682-2691 ◽  
Author(s):  
Yi Wang ◽  
Sok Ho Kim ◽  
Ramya Natarajan ◽  
Jason E. Heindl ◽  
Eric L. Bruger ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Biofilm Formation ◽  
Direct Synthesis ◽  
Wild Type ◽  
Cyclic Diguanylate ◽  
Content Type ◽  
Exogenous Addition ◽  
In The Wild ◽  
Growth Requirement ◽  
Transposon Insertions

ABSTRACTIn bacteria, the functions of polyamines, small linear polycations, are poorly defined, but these metabolites can influence biofilm formation in several systems. Transposon insertions in an ornithine decarboxylase (odc) gene inAgrobacterium tumefaciens, predicted to direct synthesis of the polyamine putrescine from ornithine, resulted in elevated cellulose. Null mutants forodcgrew somewhat slowly in a polyamine-free medium but exhibited increased biofilm formation that was dependent on cellulose production. Spermidine is an essential metabolite inA. tumefaciensand is synthesized from putrescine inA. tumefaciensvia the stepwise actions of carboxyspermidine dehydrogenase (CASDH) and carboxyspermidine decarboxylase (CASDC). Exogenous addition of either putrescine or spermidine to theodcmutant returned biofilm formation to wild-type levels. Low levels of exogenous spermidine restored growth to CASDH and CASDC mutants, facilitating weak biofilm formation, but this was dampened with increasing concentrations. Norspermidine rescued growth for theodc, CASDH, and CASDC mutants but did not significantly affect their biofilm phenotypes, whereas in the wild type, it stimulated biofilm formation and depressed spermidine levels. Theodcmutant produced elevated levels of cyclic diguanylate monophosphate (c-di-GMP), exogenous polyamines modulated these levels, and expression of a c-di-GMP phosphodiesterase reversed the enhanced biofilm formation. Prior work revealed accumulation of the precursors putrescine and carboxyspermidine in the CASDH and CASDC mutants, respectively, but unexpectedly, both mutants accumulated homospermidine; here, we show that this requires a homospermidine synthase (hss) homologue.IMPORTANCEPolyamines are small, positively charged metabolites that are nearly ubiquitous in cellular life. They are often essential in eukaryotes and more variably in bacteria. Polyamines have been reported to influence the surface-attached biofilm formation of several bacteria. InAgrobacterium tumefaciens, mutants with diminished levels of the polyamine spermidine are stimulated for biofilm formation, and exogenous provision of spermidine decreases biofilm formation. Spermidine is also essential forA. tumefaciensgrowth, but the related polyamine norspermidine exogenously rescues growth and does not diminish biofilm formation, revealing that the growth requirement and biofilm control are separable. Polyamine control of biofilm formation appears to function via effects on the cellular second messenger cyclic diguanylate monophosphate, regulating the transition from a free-living to a surface-attached lifestyle.

Identification, Properties and Genetic Control of UDP-ʟ-Rhamnose: Anthocyanidin 3-O-Glucoside, 6″-O-Rhamnosyltransferase Isolated from Retals of the Red Campion (Silene dioica)

1980 ◽  
Vol 35 (3-4) ◽  
pp. 249-257 ◽  
Author(s):  
John Kamsteeg ◽  
Jan van Brederode ◽  
Gerrit van Nigtevecht
Keyword(s):  
Biosynthetic Pathway ◽  
Dominant Gene ◽  
Divalent Metal ◽  
Hydroxyl Group ◽  
Silene Dioica ◽  
Divalent Metal Ions ◽  
Ph Optimum ◽  
Red Campion ◽  
Km Value ◽  
Reduced Rate

Abstract An enzyme catalyzing the transfer of the rhamnosyl moiety of UDP-ʟ-rhamnose to the 6 -hydroxyl group of the 3-O-bound glucose of anthocyanidin 3-O-glucosides has been demonstrated in petal extracts of Silene dioica plants. The enzyme activity is controlled by a single dominant gene N; no rhamnosyltransferase activity is found in petals of n/n plants. The 60-fold purified rhamno-syltransferase exhibits a pH optimum of 8.1, has a molecular weight of about 45000 daltons, is stimulated by the divalent metal ions Mg2+, Mn2+ and Co2+, and has a “true Km” value of 0.09 mᴍ for UDP-ʟ-rhamnose and 2.2 mᴍ for cyanidin 3-O-glucoside. Pelargonidin 3-O-glucoside and delphinidin 3-O-glucoside can also serve as acceptor. The enzyme can also catalyze the rhamnosylation of anthocyanidin 3,5-diglucosides although at reduced rate. The biosynthetic pathway for the synthesis of cyanidin 3-rhamnosylglucoside-5-glucoside in petals of S. dioica is discussed.

scholarly journals KINETICS OF LYSIS BY CLOSTRIDIUM SEPTICUM HEMOLYSIN

1944 ◽  
Vol 80 (4) ◽  
pp. 333-339 ◽  
Author(s):  
Alan W. Bernheimer
Keyword(s):  
Hydrogen Ion ◽  
Ion Concentration ◽  
Clostridium Septicum ◽  
Ph Optimum ◽  
Hydrogen Ion Concentration ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
Kinetics Of

The kinetics of the hemolytic reaction effected by the hemolysin of Clostridium septicum, strain 44, has been studied with regard to the effect of concentration, temperature, and hydrogen ion concentration on the rate of the hemolytic reaction. The kinetics of hemolysis was found to resemble in several respects that of enzyme-catalyzed reactions, but differed in the absence of a clearly defined pH optimum. Attention is drawn to differences between the hemolytic system studied and certain other hemolytic systems.

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