The Experts below are selected from a list of 188421 Experts worldwide ranked by ideXlab platform
Kevin Dybvig - One of the best experts on this subject based on the ideXlab platform.
-
dna polymerase iii of mycoplasma pulmonis isolation and characterization of the enzyme and its Structural Gene polc
Molecular Microbiology, 1994Co-Authors: Marjorie H Barnes, Paul M Tarantino, Peter Spacciapoli, Neal C Brown, Kevin DybvigAbstract:Summary Mycoplasmas have originated from Gram-positive bacteria via rapid deGenerative evolution. The results of previous investigations of mycoplasmal DNA polymerases suggest that the process of evolution has wrought a major simplification of the typical Gram-positive bacterial DNA polymerase profile, reducing it from three exonuclease (exo)-positive enzymes to a single exo-negative species. The objective of this work was to rigorousiy investigate this suggestion, focusing on the evolutionary fate of DNA polymerase III (Pol III), the enzyme which Gram-positive bacteria specifically require for replicative DNA synthesis. The approach used Mycoplasma pulmonis as the model organism and exploited Structural Gene cloning, enzymology, and Pol III-specific inhibitors of the HPUra class as investigative tools. Our results indicate that M. pulmonis has strongly conserved a single copy of a Structural Gene homologous to polC, the Gram-positive bacterial Gene encoding Pol III M. pulmonis was found to possess a DNA polymerase that displays the size, primary structure, exonuclease activity, and level of HPUra sensitivity expected of a prototypical Gram-positive Pol III. The high level of sensitivity of M. pulmonis growth to Gram-positive Pol III-selective inhibitors of the HPUra type strongly suggests that Mycoplasma has conserved not only the basic structure of Pol III, but also its essential replicative function. Evidence for a second, HPUra-resistant polymerase activity in M. pulmonis is also described, indicating that the DNA polymerase composition of Mycoplasma is complex and closer to that of Gram-positive bacteria than previously thought.
Charles S Mchenry - One of the best experts on this subject based on the ideXlab platform.
-
molecular cloning sequencing and overexpression of the Structural Gene encoding the delta subunit of escherichia coli dna polymerase iii holoenzyme
Journal of Bacteriology, 1992Co-Authors: J R Carter, M A Franden, R Aebersold, Charles S MchenryAbstract:Abstract Using an oligonucleotide hybridization probe, we have mapped the Structural Gene for the delta subunit of Escherichia coli DNA polymerase III holoenzyme to 14.6 centisomes of the chromosome. This Gene, designated holA, was cloned and sequenced. The sequence of holA matches precisely four amino acid sequences obtained for the amino terminus of delta and three internal tryptic peptides. A holA-overproducing plasmid that directs the expression of delta up to 4% of the soluble protein was constructed. Sequence analysis of holA revealed a 1,029-bp open reading frame that encodes a protein with a predicted molecular mass of 38,703 Da. holA may reside downstream of rlpB in an operon, perhaps representing yet another link between Structural Genes for the DNA polymerase III holoenzyme and proteins involved in membrane bioGenesis. These and other features are discussed in terms of Genetic regulation of delta-subunit synthesis.
Marjorie H Barnes - One of the best experts on this subject based on the ideXlab platform.
-
dna polymerase iii of mycoplasma pulmonis isolation and characterization of the enzyme and its Structural Gene polc
Molecular Microbiology, 1994Co-Authors: Marjorie H Barnes, Paul M Tarantino, Peter Spacciapoli, Neal C Brown, Kevin DybvigAbstract:Summary Mycoplasmas have originated from Gram-positive bacteria via rapid deGenerative evolution. The results of previous investigations of mycoplasmal DNA polymerases suggest that the process of evolution has wrought a major simplification of the typical Gram-positive bacterial DNA polymerase profile, reducing it from three exonuclease (exo)-positive enzymes to a single exo-negative species. The objective of this work was to rigorousiy investigate this suggestion, focusing on the evolutionary fate of DNA polymerase III (Pol III), the enzyme which Gram-positive bacteria specifically require for replicative DNA synthesis. The approach used Mycoplasma pulmonis as the model organism and exploited Structural Gene cloning, enzymology, and Pol III-specific inhibitors of the HPUra class as investigative tools. Our results indicate that M. pulmonis has strongly conserved a single copy of a Structural Gene homologous to polC, the Gram-positive bacterial Gene encoding Pol III M. pulmonis was found to possess a DNA polymerase that displays the size, primary structure, exonuclease activity, and level of HPUra sensitivity expected of a prototypical Gram-positive Pol III. The high level of sensitivity of M. pulmonis growth to Gram-positive Pol III-selective inhibitors of the HPUra type strongly suggests that Mycoplasma has conserved not only the basic structure of Pol III, but also its essential replicative function. Evidence for a second, HPUra-resistant polymerase activity in M. pulmonis is also described, indicating that the DNA polymerase composition of Mycoplasma is complex and closer to that of Gram-positive bacteria than previously thought.
Robert A Bender - One of the best experts on this subject based on the ideXlab platform.
-
A Nonsense Mutation in the Structural Gene for Glutamine Synthetase Leading to Loss of Nitrogen Regulation in Klebsiella aeroGenes
2016Co-Authors: Robert A Bender, Linda J. EadesAbstract:Summary. An amber mutation (glnA3711), the first non-sense mutation isolated in Klebsiella eroGenes, i described. When amber suppressors were present, the mutant made active glutamine synthetase which was more thermolabile than wild type, showing that glnA3711 lies in the Structural Gene for glutamine synthetase. Strains carrying the glnA3711 allele were unable to express nitrogen regulation of Genes coding for histidase, asparaginase, and glutamate dehydrogenase unless amber suppressors were also present. These results support a model that expression of Gene(s) from the glnA promoter is required for nitrogen regulation in K. aeroGenes. Previous reports have suggested that the biosynthetic en-zyme glutamine synthetase (GS) served a second role as an activator of Gene expression for Genes involved in nitro
-
growth inhibition caused by overexpression of the Structural Gene for glutamate dehydrogenase gdha from klebsiella aeroGenes
Journal of Bacteriology, 2001Co-Authors: Brian K Janes, Pablo J Pomposiello, Ana Perezmatos, David J Najarian, Thomas J Goss, Robert A BenderAbstract:Two linked mutations affecting glutamate dehydrogenase (GDH) formation (gdh-1 and rev-2) had been isolated at a locus near the trp cluster in Klebsiella aeroGenes. The properties of these two mutations were consistent with those of a locus containing either a regulatory Gene or a Structural Gene. The gdhA Gene from K. aeroGenes was cloned and sequenced, and an insertion mutation was Generated and shown to be linked to trp. A region of gdhA from a strain bearing gdh-1 was sequenced and shown to have a single-base-pair change, confirming that the locus defined by gdh-1 is the Structural Gene for GDH. Mutants with the same phenotype as rev-2 were isolated, and their sequences showed that the mutations were located in the promoter region of the gdhA Gene. The linkage of gdhA to trp in K. aeroGenes was explained by postulating an inversion of the Genetic map relative to other enteric bacteria. Strains that bore high-copy-number clones of gdhA displayed an auxotrophy that was interpreted as a limitation for alpha-ketoglutarate and consequently for succinyl-coenzyme A (CoA). Three lines of evidence supported this interpretation: high-copy-number clones of the enzymatically inactive gdhA1 allele showed no auxotrophy, repression of GDH expression by the nitrogen assimilation control protein (NAC) relieved the auxotrophy, and addition of compounds that could increase the alpha-ketoglutarate supply or reduce the succinyl-CoA requirement relieved the auxotrophy.
Neal C Brown - One of the best experts on this subject based on the ideXlab platform.
-
dna polymerase iii of mycoplasma pulmonis isolation and characterization of the enzyme and its Structural Gene polc
Molecular Microbiology, 1994Co-Authors: Marjorie H Barnes, Paul M Tarantino, Peter Spacciapoli, Neal C Brown, Kevin DybvigAbstract:Summary Mycoplasmas have originated from Gram-positive bacteria via rapid deGenerative evolution. The results of previous investigations of mycoplasmal DNA polymerases suggest that the process of evolution has wrought a major simplification of the typical Gram-positive bacterial DNA polymerase profile, reducing it from three exonuclease (exo)-positive enzymes to a single exo-negative species. The objective of this work was to rigorousiy investigate this suggestion, focusing on the evolutionary fate of DNA polymerase III (Pol III), the enzyme which Gram-positive bacteria specifically require for replicative DNA synthesis. The approach used Mycoplasma pulmonis as the model organism and exploited Structural Gene cloning, enzymology, and Pol III-specific inhibitors of the HPUra class as investigative tools. Our results indicate that M. pulmonis has strongly conserved a single copy of a Structural Gene homologous to polC, the Gram-positive bacterial Gene encoding Pol III M. pulmonis was found to possess a DNA polymerase that displays the size, primary structure, exonuclease activity, and level of HPUra sensitivity expected of a prototypical Gram-positive Pol III. The high level of sensitivity of M. pulmonis growth to Gram-positive Pol III-selective inhibitors of the HPUra type strongly suggests that Mycoplasma has conserved not only the basic structure of Pol III, but also its essential replicative function. Evidence for a second, HPUra-resistant polymerase activity in M. pulmonis is also described, indicating that the DNA polymerase composition of Mycoplasma is complex and closer to that of Gram-positive bacteria than previously thought.
