Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Extensive knowledge exists in Escherichia coli about the contiguous pheA and aroF-tyrA operons which have opposite transcription orientations and are separated by a bidirectional transcription terminator. The corresponding structural genes and individual components of the terminator and attenuator from Erwinia herbicola have been analyzed from an evolutionary vantage point. A 7.5-kb DNA fragment from E. herbicola carrying the linked pheA, tyrA, and aroF genes was cloned by functional complementation of E. coli auxotrophic requirements. A 3,433-bp segment of DNA consisting of more than half of aroF, all of tyrA, and the entire phenylalanine operon (promoter, leader region encoding the leader peptide and containing the phe attenuator, and pheA) was sequenced. A bidirectional transcription terminator was positioned between the divergently transcribed pheA and tyrA. The adjacent aroF and tyrA genes share a common transcription orientation, consistent with their probable coexistence within an operon. However, tyrA can be expressed efficiently from an internal promoter which appears to lie within the 3' portion of aroF. The gene order is pheA tyrA aroF in E. herbicola, with the same tail-to-tail arrangement of transcription known to exist in E. coli. The pheL coding region of the phe operon was dominated by phenylalanine codons, seven of the 15 amino acid residues of the leader peptide being L-phenylalanine. The E. herbicola pheA and tyrA genes were 1,161 bp and 1,119 bp in length, respectively, and corresponded to deduced gene products having subunit molecular weights of 43,182 and 41,847. The deduced amino acid sequences of PheA and TyrA were homologous at their N-termini, consistent with a common evolutionary origin of the chorismate mutase domains present at the amino terminus of both PheA and TyrA. A detailed comparison of the E. coli and E. herbicola sequences was made. The pheA, tyrA, and aroF genes of E. herbicola exhibited high overall identity with the counterpart E. coli genes. Within the leader region of the phe operon, the leader peptide coding region was highly conserved. Although the 1:2 and 2':3' stems defining the pause structure and the antiterminator, respectively, were also highly conserved, RNA segment 4 of the attenuator terminator exhibited considerable divergence, as did the distal portion of the attenuator region. Within the span of attenuator region encoding the three stem-loop structures of mRNA secondary configuration, hot spots of base-residue divergence were localized to looped-out regions. No changes occurred which would simultaneously disrupt alternative pairing relationships of secondary configuration. The bidirectional terminator between pheA and tyrA has diverged very substantially.(ABSTRACT TRUNCATED AT 400 WORDS)
J Mol Evol 1993 Feb
PMID:The pheA/tyrA/aroF region from Erwinia herbicola: an emerging comparative basis for analysis of gene organization and regulation in enteric bacteria. 809 64

A cDNA coding for chorismate mutase was isolated from tomato by complementing a chorismate mutase-deficient Escherichia coli strain with a cDNA library. Southern blot analysis suggests the existence of a single gene of this chorismate mutase type per haploid tomato genome. The abundance of the corresponding transcripts was highest in roots, lower in stems and cotyledons, and even lower in flowers and leaves. The activity of the protein expressed in E. coli was not regulated by the three aromatic amino acids. Characteristics of the sequence and of the enzymatic activity suggest that the identified cDNA encodes a cytosolic, unregulated CM-2 type chorismate mutase.
Plant Mol Biol 1996 Jul
PMID:Isolation of a cDNA from tomato coding for an unregulated, cytosolic chorismate mutase. 880 22

The structure of the complex of the chorismate mutase from the yeast Saccharomyces cerevisiae with a transition state analog is constructed using a suite of docking tools. The construction finds the best location for the active site in the enzyme, and the best orientation of the analog compound in the active site. The resulting complex shows extensive salt links and hydrogen bonds between the enzyme and the compound, including those mediated by water molecules. A network of polar interactions between amino acid residues is found to solidify the active site of the enzyme. The enzymatic mechanism suggested for a bacterial chorismate mutase, that the active site is by design capable of selecting an active conformer of the substrate, and of stabilizing the transition state, is apparently intact in the yeast enzyme. No direct evidence is found to support an alternative mechanism which involves specific catalytic groups, although the possibility is not eliminated. This finding reinforces the notion of a function being evolutionarily conserved via a common mechanism, rather than via sequential or structural homology.
J Mol Biol 1997 Sep 05
PMID:Investigation of the enzymatic mechanism of the yeast chorismate mutase by docking a transition state analog. 929 31

Root-knot nematodes are obligate plant parasites that alter plant cell growth and development by inducing the formation of giant feeder cells. It is thought that nematodes inject secretions from their esophageal glands into plant cells while feeding, and that these secretions cause giant cell formation. To elucidate the mechanisms underlying the formation of giant cells, a strategy was developed to clone esophageal gland genes from the root-knot nematode Meloidogyne javanica. One clone, shown to be expressed in the nematode's esophageal gland, codes for a potentially secreted chorismate mutase (CM). CM is a key branch-point regulatory enzyme in the shikimate pathway and converts chorismate to prephenate, a precursor of phenylalanine and tyrosine. The shikimate pathway is not found in animals, but in plants, where it produces aromatic amino acids and derivative compounds that play critical roles in growth and defense. Therefore, we hypothesize that this CM is involved in allowing nematodes to parasitize plants.
Mol Plant Microbe Interact 1999 Apr
PMID:Cloning and characterization of an esophageal-gland-specific chorismate mutase from the phytoparasitic nematode Meloidogyne javanica. 1018 71

Sequencing of an 8182-bp chromosomal region in Pseudomonas stutzeri revealed the major portion of an apparent mixed-function supraoperon (defined as a nested organization of transcriptional units encoding gene products which function in more than one biochemical pathway). A nearly identical supraoperon organization was apparent in the unpublished Pseudomonas aeruginosa genome database, where the complete Pseudomonas supraoperon was deduced. The serC(pdxF)-aroQp. pheA-hisHb-tyrAc-aroF-cmk-rpsA supraoperon encodes 3-phosphoserine aminotransferase, a bidomain chorismate mutase/prephenate dehydratase, imidazole acetol-phosphate aminotransferase, cyclohexadienyl dehydrogenase, 5-enolpyruvylshikimate 3-phosphate synthase, cytidylate kinase, and ribosomal protein S1. The member genes were identified by homology analysis, enzyme assay, and/or functional complementation. Although SerC(PdxF) and HisHb exercise their primary functions in serine, pyridoxine, and histidine biosynthesis, they also have critical catalytic roles in provision of the sidechain amino groups of tryptophan, phenylalanine, and tyrosine. The likelihood of supraoperon-wide translational coupling is suggested by the highly compressed intergenic spacing (including overlapping stop and start codons), as well as by possible hairpin structures in mRNA which may sequester some of the ribosome-binding sites and thus provide a mechanism for translational coupling. A comparison of the organization of the supraoperon genes in other organisms represented in the database revealed unmistakable conservation of the linkage of these genes across wide phylogenetic boundaries, albeit with considerable gene shuffling. At least remnants and shuffled portions of the entire supraoperon are distributed throughout the Gram-negative bacteria with the hisHb-tyrA-aroF gene block being conserved as distantly as the gram-positive bacteria. Such conservation of mixed-function genes may reflect the selective value of still-unknown global relationships of protein-protein interaction or regulation.
J Mol Evol 1999 Jul
PMID:A probable mixed-function supraoperon in Pseudomonas exhibits gene organization features of both intergenomic conservation and gene shuffling. 1036 39

The crystal structure of the Bacillus subtilis chorismate mutase, an enzyme of the aromatic amino acids biosynthetic pathway, was determined to 1.30 A resolution. The structure of the homotrimer was determined by molecular replacement using orthorhombic crystals of space group P2(1)2(1)2(1) with unit-cell parameters a = 52.2, b = 83. 8, c = 86.0 A. The ABC trimer of the monoclinic crystal structure [Chook et al. (1994), J. Mol. Biol. 240, 476-500] was used as the starting model. The final coordinates are composed of three complete polypeptide chains of 127 amino-acid residues. In addition, there are nine sulfate ions, five glycerol molecules and 424 water molecules clearly visible in the structure. This structure was refined with aniosotropic temperature factors, has excellent geometry and a crystallographic R factor of 0.169 with an R(free) of 0.236. The three active sites of the macromolecule are at the subunit interfaces, with residues from two subunits contributing to each site. This orthorhombic crystal form was grown using ammonium sulfate as the precipitant; glycerol was used as a cryoprotectant during data collection. A glycerol molecule and sulfate ion in each of the active sites was found mimicking a transition-state analog. In this structure, the C-terminal tails of the subunits of the trimer are hydrogen bonded to residues of the active site of neighboring trimers in the crystal and thus cross-link the molecules in the crystal lattice.
 ...
PMID:The 1.30 A resolution structure of the Bacillus subtilis chorismate mutase catalytic homotrimer. 1081 43

The V(H) region of the murine antibody 1F7 has been identified as a single-domain chorismate mutase, but a tendency to denature and aggregate has hampered its biochemical characterization. Standard mutagenesis approaches targeting antibody chain dimerization areas have been exhausted. We describe a new approach to the problem, where we use molecular dynamics (MD) simulations to find the differences between the untractable protein and the known soluble V(H) domain from a llama antibody. MD simulations of proteins yield information on the relative stability and fluctuations of parts of the proteins. By comparing simulation results of two related proteins their differences in stability and fluctuations can be analyzed and may suggest mutations aimed at (de)stabilization of one of the two proteins. For the mouse versus llama simulations, this approach highlights an untried area in the protein which shows increased fluctuations. The replacement of this eight-residue segment with the corresponding llama sequence gave a chimeric mutant which shows significantly decreased fluctuations. We see this as a general scheme to generate suggestions for mutagenesis experiments, not only obviously generalizable to other immunoglobulin domains, but to other protein systems as well.
J Mol Biol 2000 Jul 21
PMID:Molecular dynamics simulations highlight mobile regions in proteins: A novel suggestion for converting a murine V(H) domain into a more tractable species. 1089 Dec 81

Allosteric regulation of key metabolic enzymes is a fascinating field to study the structure-function relationship of induced conformational changes of proteins. In this review we compare the principles of allosteric transitions of the complex classical model aspartate transcarbamoylase (ATCase) from Escherichia coli, consisting of 12 polypeptides, and the less complicated chorismate mutase derived from baker's yeast, which functions as a homodimer. Chorismate mutase presumably represents the minimal oligomerization state of a cooperative enzyme which still can be either activated or inhibited by different heterotropic effectors. Detailed knowledge of the number of possible quaternary states and a description of molecular triggers for conformational changes of model enzymes such as ATCase and chorismate mutase shed more and more light on allostery as an important regulatory mechanism of any living cell. The comparison of wild-type and engineered mutant enzymes reveals that current textbook models for regulation do not cover the entire picture needed to describe the function of these enzymes in detail.
Microbiol Mol Biol Rev 2001 Sep
PMID:Allosteric regulation of catalytic activity: Escherichia coli aspartate transcarbamoylase versus yeast chorismate mutase. 1152 3

Quantitative data on Salmonella gene expression in infected hosts are largely lacking because of technical problems. One attractive reporter, the green fluorescent protein (GFP), is widely used in vitro but is difficult to quantify in infected tissues because of the preponderance of background particles with similar fluorescence. Here, bacterial GFP emission was spectrally distinguished from host autofluorescence by two-colour flow cytometry. Using this technique, the in vivo activity of three well-characterized promoters (PsicA, PssaH and PpagC) was determined. Their spatial and temporal activity patterns are in close agreement with predictions based on previous data and the colonization defects of corresponding deletion strains. To identify additional Salmonella promoters that are induced in infected animals, a genomic library was sorted by flow cytometry yielding four independent promoters. Genes expressed from PpibB and PsifA contribute to virulence, and chorismate mutase expressed from ParoQ might participate in aromatic acid biosynthesis, which is also required for virulence. Promoter P3g appears to be part of a mobile genetic element that is lacking in the completely sequenced strain LT2.
Mol Microbiol 2002 Mar
PMID:Examination of Salmonella gene expression in an infected mammalian host using the green fluorescent protein and two-colour flow cytometry. 1191 12

Root-knot nematodes are obligate plant parasites that alter plant cell growth and development by inducing the formation of giant cells for feeding. Nematodes inject secretions from their esophageal glands through their stylet and into plant cells to induce giant cell formation. Meloidogyne javanica chorismate mutase 1 (MjCM-1) is one such esophageal gland protein likely to be secreted from the nematode as giant cells form. MjCM-1 has two domains, an N-terminal chorismate mutase (CM) domain and a C-terminal region of unknown function. It is the N-terminal CM domain of the protein that is the predominant form produced in root-knot nematodes. Transgenic expression of MjCM-1 in soybean hairy roots results in a phenotype of reduced and aborted lateral roots. Histological studies demonstrate the absence of vascular tissue in hairy roots expressing MjCM-1. The phenotype of MjCM-1 expressed at low levels can be rescued by the addition of indole-3-acetic acid (IAA), indicating MjCM-1 overexpression reduces IAA biosynthesis. We propose MjCM-1 lowers IAA by causing a competition for chorismate, resulting in an alteration of chorismate-derived metabolites and, ultimately, in plant cell development. Therefore, we hypothesize that MjCM-1 is involved in allowing nematodes to establish a parasitic relationship with the host plant.
Mol Plant Microbe Interact 2003 Feb
PMID:Meloidogyne javanica chorismate mutase 1 alters plant cell development. 1257 46


<< Previous 1 2 3 4 5 Next >>