The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Jan Martinussen - One of the best experts on this subject based on the ideXlab platform.
-
phosphoribosyl diphosphate prpp biosynthesis enzymology utilization and metabolic significance
Microbiology and Molecular Biology Reviews, 2017Co-Authors: Bjarne Hovejensen, Jan Martinussen, Robert L. Switzer, Kasper R Andersen, Mogens Kilstrup, Martin WillemoesAbstract:SUMMARY Phosphoribosyl diphosphate (PRPP) is an important intermediate in cellular metabolism. PRPP is synthesized by PRPP synthase, as follows: ribose 5-phosphate + ATP → PRPP + AMP. PRPP is ubiquitously found in living organisms and is used in substitution reactions with the formation of glycosidic bonds. PRPP is utilized in the biosynthesis of purine and pyrimidine nucleotides, the amino acids histidine and tryptophan, the cofactors NAD and tetrahydromethanopterin, arabinosyl monophosphodecaprenol, and certain aminoglycoside antibiotics. The participation of PRPP in each of these metabolic pathways is reviewed. Central to the metabolism of PRPP is PRPP synthase, which has been studied from all kingdoms of life by classical mechanistic procedures. The results of these analyses are unified with recent progress in molecular enzymology and the elucidation of the three-dimensional structures of PRPP synthases from eubacteria, archaea, and humans. The structures and mechanisms of catalysis of the five diphosphoryltransferases are compared, as are those of selected enzymes of diphosphoryl transfer, phosphoryl transfer, and nucleotidyl transfer reactions. PRPP is used as a substrate by a large number Phosphoribosyltransferases. The protein structures and reaction mechanisms of these Phosphoribosyltransferases vary and demonstrate the versatility of PRPP as an intermediate in cellular physiology. PRPP synthases appear to have originated from a Phosphoribosyltransferase during evolution, as demonstrated by phylogenetic analysis. PRPP, furthermore, is an effector molecule of purine and pyrimidine nucleotide biosynthesis, either by binding to PurR or PyrR regulatory proteins or as an allosteric activator of carbamoylphosphate synthetase. Genetic analyses have disclosed a number of mutants altered in the PRPP synthase-specifying genes in humans as well as bacterial species.
-
cloning and characterization of upp a gene encoding uracil Phosphoribosyltransferase from lactococcus lactis
Journal of Bacteriology, 1994Co-Authors: Jan Martinussen, Karin HammerAbstract:Uracil Phosphoribosyltransferase catalyzes the key reaction in the salvage of uracil in many microorganisms. The gene encoding uracil Phosphoribosyltransferase (upp) was cloned from Lactococcus lactis subsp. cremoris MG1363 by complementation of an Escherichia coli mutant. The gene was sequenced, and the putative amino acid sequence was deduced. The promoter was mapped by both primer extension and analysis of beta-galactosidase expressed from strains carrying fusion between upp promoter fragments and the lacLM gene. The results showed that the upp gene was expressed from its own promoter. After in vitro construction of an internal deletion, a upp mutant was constructed by a double-crossover event. This implicated the utilization of a plasmid with a thermosensitive origin of replication and a new and easy way to screen for double crossover events in both gram-positive and gram-negative bacterial strains. The phenotype of the uracil Phosphoribosyltransferase-deficient strain was established. Surprisingly, the upp strain is resistant only to very low concentrations of 5-fluorouracil. Secondary mutants in thymidine phosphorylase and thymidine kinase were isolated by selection for resistance to high concentrations of 5-fluorouracil.
James C Sacchettini - One of the best experts on this subject based on the ideXlab platform.
-
crystal structure of quinolinic acid Phosphoribosyltransferase from mycobacterium tuberculosis a potential tb drug target
Structure, 1998Co-Authors: Vivek Sharma, Charles Grubmeyer, James C SacchettiniAbstract:Abstract Background: Mycobacterium tuberculosis is the single most deadly human pathogen and is responsible for nearly three million deaths every year. Recent elucidation of the mode of action of isoniazid, a frontline antimycobacterial drug, suggests that NAD metabolism is extremely critical for this microorganism. M. tuberculosis depends solely on the de novo pathway to meet its NAD demand. Quinolinic acid Phosphoribosyltransferase (QAPRTase), a key enzyme in the de novo biosynthesis of NAD, provides an attractive target for designing novel antitubercular drugs. Results: The X-ray crystal structure of the M. tuberculosis QAPRTase apoenzyme has been determined by multiple isomorphous replacement at 2.4 a resolution. Structures of the enzyme have also been solved in complex with the substrate quinolinic acid (QA), the inhibitory QA analog phthalic acid (PA), the product nicotinate mononucleotide (NAMN), and as a ternary complex with PA and a substrate analog, 5-phosphoribosyl-1-( β -methylene)pyrophosphate (PRPCP). The structure of the nonproductive QAPRTase–PA–PRPCP Michaelis complex reveals a 5-phosphoribosyl-1-pyrophosphate-binding site that is different from the one observed in type I Phosphoribosyltransferases (PRTases). The type II PRTase active site of QAPRTase undergoes conformational changes that appear to be important in determining substrate specificity and eliciting productive catalysis. Conclusions: QAPRTase is the only known representative of the type II PRTase fold, an unusual α / β barrel, and appears to represent convergent evolution for PRTase catalysis. The active site of type II PRTase bears little resemblance to the better known type I enzymes.
-
crystal structure of orotate Phosphoribosyltransferase
Biochemistry, 1994Co-Authors: Giovanna Scapin, Charles Grubmeyer, James C SacchettiniAbstract:Phosphoribosyltransferases (PRTases) are enzymes involved in the synthesis of purine, pyrimidine, and pyridine nucleotides. They utilize α-D-5-phosphoribosyl-1-pyrophosphate (PRPP) and a nitrogenous base to form a β-N-riboside monophosphate and pyrophosphate (PP i ), and their functional significance in nucleotide homeostasis is evidenced by the devastating effects of inherited diseases associated with the decreased activity and/or stability of these enzymes. The 2.6-A structure of the Salmonella typhimurium orotate Phosphoribosyltransferase (OPRTase) complexed with its product orotidine monophosphate (OMP) provides the first detailed image of a member of this group of enzymes
Karin Hammer - One of the best experts on this subject based on the ideXlab platform.
-
cloning and characterization of upp a gene encoding uracil Phosphoribosyltransferase from lactococcus lactis
Journal of Bacteriology, 1994Co-Authors: Jan Martinussen, Karin HammerAbstract:Uracil Phosphoribosyltransferase catalyzes the key reaction in the salvage of uracil in many microorganisms. The gene encoding uracil Phosphoribosyltransferase (upp) was cloned from Lactococcus lactis subsp. cremoris MG1363 by complementation of an Escherichia coli mutant. The gene was sequenced, and the putative amino acid sequence was deduced. The promoter was mapped by both primer extension and analysis of beta-galactosidase expressed from strains carrying fusion between upp promoter fragments and the lacLM gene. The results showed that the upp gene was expressed from its own promoter. After in vitro construction of an internal deletion, a upp mutant was constructed by a double-crossover event. This implicated the utilization of a plasmid with a thermosensitive origin of replication and a new and easy way to screen for double crossover events in both gram-positive and gram-negative bacterial strains. The phenotype of the uracil Phosphoribosyltransferase-deficient strain was established. Surprisingly, the upp strain is resistant only to very low concentrations of 5-fluorouracil. Secondary mutants in thymidine phosphorylase and thymidine kinase were isolated by selection for resistance to high concentrations of 5-fluorouracil.
Bente Mygind - One of the best experts on this subject based on the ideXlab platform.
-
characterization of the upp gene encoding uracil Phosphoribosyltransferase of escherichia coli k12
FEBS Journal, 1992Co-Authors: Paal Skytt Andersen, John M Smith, Bente MygindAbstract:The upp gene coding for uracil Phosphoribosyltransferase was subcloned on a 5-kb EcoRI restriction fragment along with the purMN operon. By a combination of complementation, deletion and minicell analyses, the upp gene was located adjacent to and divergently transcribed from the purMN operon. All three gene products could be identified in minicell extracts. The cloned upp gene shows an elevated expression upon uracil starvation. The nucleotide sequence and transcription start of the gene were determined. The sequence yields an open reading frame of 624 nucleotides encoding a protein of 22.5 kDa which is in agreement with the previously determined subunit M, of the purified enzyme. A putative 5-phosphoribosyl-a-1 -diphosphate (PRPP) binding site has been identified which is similar to the PRPP binding site of the yeast uracil Phosphoribosyltransferase.
Yong Kyung Choe - One of the best experts on this subject based on the ideXlab platform.
-
complete sequence of the upp gene encoding uracil Phosphoribosyltransferase from mycobacterium bovis bcg
Iubmb Life, 1997Co-Authors: Young Jun Kang, Young Kil Park, Tai Wha Chung, Sang-won Kang, Sue Nie Park, In Seong Choe, Yong Kyung ChoeAbstract:MOLECULAR BIOLOGY INTERNATIONAL Pages 1117-1124 COMPLETE SEQUENCE OF THE UPP GENE ENCODING URACIL PHOSPHOR1BOSYLTRANSFERASE FROM MYCOBACTERIUM BOVIS BCG Jin Koo Kim, Jeong Hyun Kim, Setmg-Hwan Lee, Young Kang, Jong-Seok Lim, Hee Gu Lee, Sang Jae Kim ~, Gill Han Bai ~, Young Kil Park ~, Sang-Hyun Cho ~, Sang Won Kang-, Yu Sam Knn-, In Seong Choe, Tai Wha Chung, Sue-Nie Park Seung Ho Kim, Jong Seog Ahn, and Yong-Kytmg Choe * Korea Research Institute of Bioscience & Biotechnology, KIST, Taejon, 305-600, ~Korea Institute of Tuberct.losis, KNTA, Seoul, 137-140, 2Department of Biochemistry, Yonsei Ulfiversity, Seoul, 120-749, Korea Received Fcbruary 8, 1997 SUMMARY : The nucleotide sequence of a 799 bp fragment of Mycobacterium bov& BCG containing the putative upp genc that encodes a uracil Phosphoribosyltransferase (UPRTase [EC 2.4.2.9]) has been determined. The upp gene of BCG has an open reading frame (ORF) of 621 bp (207 amino acids) starting with GTG (position 112) and ending with TGA (position 733), and its molecular mass was calculated to be 21,864 Da. Comparative analyses of the deduced amino acid sequence of BCG UPRTasc with the UPRTase of six bacterial genera revealed that 24% (50/211) of the residues are perfectly conservcd and 32% (67/211) of the residues are well conserved. Key Words : upp, uracil Phosphoribosyltransferase, BCG INTRODUCTION Myeobacterium bovis bacille Calmette-Guerin (BCG), an attenuated bovine tubercle bacillus, is the most widely used live vaccine against tuberculosis (1). It is also used for superficial bladder cancer ilmaaunotherapy (2) and offers unique advantages for developnaent as a multivalent vaccine vehicle (3, 4). Although we still do not understand the efficacy, behavior, and impact of a BCG, genetically modified BCG might secret functional routine cytokines (5) and elicit systemic and mucosal il~mmity (6, 7). Major obstacles to development of BeG as a multivalent vaccine vetficle o1" immtme modulator are its slow growth, the low state of current knowledge about its
