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Query: UNIPROT:P06889 (Mol)
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The virulence functions of Yersinia enterocolitica include the pYV-encoded Yop proteins and YadA adhesin as well as the chromosome-encoded enterotoxin, Yst. The yop and yadA genes form a temperature-activated regulon controlled by the transcriptional activator VirF. Gene virF, also localized on pYV, is itself thermoinduced in the absence of other pYV genes. The enterotoxin yst gene is silent in some collection strains including strain W22703. This paper describes two Tn5-Tc1 chromosomal insertion mutants of W22703 transcribing virF, and hence the yop and yadA genes, at low temperature. These mutants also resumed their production of Yst, with its typical temperature dependence. Both mutations were insertions in the same gene called ymoA for 'Yersinia modulator'. The cloned ymoA gene fully complemented the two mutations. Several properties of the mutants suggest that ymoA encodes a histone-like protein. According to the nucleic acid sequence, the product of ymoA is an 8064 Da protein rich in aspartic acid (9%), glutamic acid (9%) and lysine (10.5%), but the predicted amino acid sequence shows no similarity with any described histone-like protein. This work supports recent reports which propose a role for DNA topology and bacterial chromatin structure in thermoregulation of virulence functions.
Mol Microbiol 1991 May
PMID:ymoA, a Yersinia enterocolitica chromosomal gene modulating the expression of virulence functions. 195 83

We have cloned and sequenced over 9 kb of the mitochondrial genome from the sea star Pisaster ochraceus. Within a continuous 8.0-kb fragment are located the genes for NADH dehydrogenase subunits 1, 2, 3, and 4L (ND1, ND2, ND3, and ND4L), cytochrome oxidase subunits I, II, and III (COI, COII, and COIII), and adenosine triphosphatase subunits 6 and 8 (ATPase 6 and ATPase 8). This large fragment also contains a cluster of 13 tRNA genes between ND1 and COI as well as the genes for isoleucine tRNA between ND1 and ND2, arginine tRNA between COI and ND4L, lysine tRNA between COII and ATPase 8, and the serine (UCN) tRNA between COIII and ND3. The genes for the other five tRNAs lie outside this fragment. The gene for phenylalanine tRNA is located between cytochrome b and the 12S ribosomal genes. The genes for tRNA(glu) and tRNA(thr) are 3' to 12S ribosomal gene. The tRNAs for histidine and serine (AGN) are adjacent to each other and lie between ND4 and ND5. These data confirm the novel gene order in mitochondrial DNA (mtDNA) of sea stars and delineate additional distinctions between the sea star and other mtDNA molecules.
J Mol Evol 1990 Sep
PMID:Nucleotide sequence of nine protein-coding genes and 22 tRNAs in the mitochondrial DNA of the sea star Pisaster ochraceus. 197 16

The gene for ricin toxin A chain was modified by site-specific mutagenesis to change arginine 180 to alanine, glutamine, methionine, lysine, or histidine. Separately, glutamic acid 177 was changed to alanine and glutamic acid 208 was changed to aspartic acid. Both the wild-type and mutant proteins were expressed in Escherichia coli and, when soluble, purified and tested quantitatively for enzyme activity. A positive charge at position 180 was found necessary for solubility of the protein and for enzyme activity. Similarly, a negative charge with a proper geometry in the vicinity of position 177 was critical for ricin toxin A chain catalysis. When glutamic acid 177 was converted to alanine, nearby glutamic acid 208 could largely substitute for it. This observation provided valuable structural information concerning the nature of second-site mutations.
Mol Cell Biol 1990 Dec
PMID:Role of arginine 180 and glutamic acid 177 of ricin toxin A chain in enzymatic inactivation of ribosomes. 197 25

Human basic fibroblast growth factor (hbFGF) has been modified, with Ala3 and Ser5 substituted by glutamic acid, and the purified recombinant protein has been crystallized. The crystals are triclinic (space group P1) with unit cell parameters a = 31.0 A, b = 33.6 A, c = 34.7 A, alpha = 88 degrees, beta = 85 degrees, gamma = 76 degrees, and they diffract to at least 2 A.
J Mol Biol 1991 Apr 05
PMID:Preliminary X-ray crystallographic analysis of a modified basic fibroblast growth factor. 201 39

Charge interactions between alpha-helical coiled-coil proteins have been postulated to determine the alignment of many filamentous proteins, such as myosin heavy-chain rod, paramyosin and alpha-keratin. Here we determined the sequence changes in nine mutations in the unc-15 paramyosin gene of Caenorhabditis elegans, including one nonsense, four missense, one deletion and three suppressor mutations. These mutation sites were located on a molecular model, constructed by optimizing charge interactions between paramyosin rods. Remarkably, single charge reversals (e.g., glutamic acid to lysine) were found that either disrupted or restored filament assembly in vivo. The positions of the mutations within the paramyosin molecule support the models of paramyosin assembly and further suggest that the C-terminal region containing a cluster of five mutations, and a site interacting with it, play a key role in assembly. One amino acid substitution in this C-terminal region, in which there is a "weak spot", led to a loss of reactivity with one monoclonal anti-paramyosin antibody. The results demonstrate how a single amino acid substitution can alter the assembly properties of alpha-helical molecules.
J Mol Biol 1991 Jun 05
PMID:Single charge change on the helical surface of the paramyosin rod dramatically disrupts thick filament assembly in Caenorhabditis elegans. 205 82

Genomic clones of Drosophila and Tetrahymena histone H2A variants were isolated using the corresponding cDNA clones (van Daal et al. 1988; White et al. 1988). The site corresponding to the initiation of transcription was defined by primer extension for both Drosophila and Tetrahymena genomic sequences. The sequences of the genomic clones revealed the presence of introns in each of the genes. The Drosophila gene has three introns: one immediately following the initiation codon, one between amino acids 26 and 27 (gln and phe), and one between amino acids 64 and 65 (glu and val). The Tetrahymena gene has two introns, the positions of which are identical to the first two introns of the Drosophila gene. The chicken H2A.F variant gene has been recently sequenced and it contains four introns (Dalton et al. 1989). The first three of these are in the same positions as the introns in the Drosophila gene. The fourth intron interrupts amino acid 108 (gly). In all cases the sizes and the sequences of the introns are divergent. However, the fact that they are in conserved positions suggests that at least two of the introns were present in the ancestral gene. A phylogenetic tree constructed from the sequences of the variant and major cell cycle-regulated histone H2A proteins from several species indicates that the H2A variant proteins are evolutionarily separate and distinct from the major cell cycle-regulated histone H2A proteins. The ancestral H2A gene must have duplicated and diverged before fungi and ciliates diverged from the rest of the eukaryote lineage. In addition, it appears that the variant histone H2A proteins analyzed here are more conserved than the major histone H2A proteins.
J Mol Evol 1990 May
PMID:Conservation of intron position indicates separation of major and variant H2As is an early event in the evolution of eukaryotes. 211 57

Most ciliates use a particular genetic code where the standard stop codons UAA and UAG encode glutamine. Ciliate genes cannot therefore be expressed in heterologous systems such as Escherichia coli. To overcome this problem, we worked out a system of inducible suppression to permit efficient readthrough of UAAs and UAGs: a strong UAA tRNA suppressor that inserts glutamic acid was cloned downstream from a tac promoter whose efficiency was reduced by a transcription terminator. This system proved to be operational (1) to suppress UAG mutations by wobble pairing in an E. coli lacI-lacZ gene fusion and (2) to read through at least eight UAA glutamine codons in a Paramecium alpha-tubulin gene, as detected by Western blotting and colony hybridization. This work opens the way for cloning Ciliate genes from expression libraries and for expressing particular sequences without extended in vitro mutagenesis. A similar approach can be envisaged for expression of genes from Mycoplasma, mitochondria or other genomes that use non-standard genetic codes.
J Mol Biol 1990 Nov 20
PMID:Expression of a ciliate gene in Escherichia coli using a suppressor tRNA to read the UAA and UAG glutamine codons. 212 36

An alpha 2-adrenergic receptor subtype has been isolated from a human genomic spleen library using the human 5-hydroxytryptamine1A receptor gene (also known as G-21) as a probe. This adrenergic receptor gene encodes a protein of 450 amino acids and does not contain any consensus sequences for N-linked glycosylation in its amino terminus or extracellular loops. This receptor is also distinguished by the presence of 12 consecutive glutamic acid residues in the region of its third intracellular loop. The deduced amino acid sequence shows greatest homology to previously cloned human alpha 2-adrenergic receptors and has structural similarities to other guanine nucleotide-binding protein-coupled receptors. The DNA encoding the human alpha 2 receptor was stably transfected into mouse fibroblast Ltk- cells and radioligand binding studies were performed using the alpha 2 antagonist [3H]rauwolscine. [3H]Rauwolscine bound with high affinity (Kd = 0.33 nM) and in a saturable manner (Bmax = 1.4 pmol/mg of protein). Pharmacological characterization of this receptor indicated a rank order of potency of yohimbine greater than prazosin greater than oxymetazoline. Additionally, 100 microM 5'-guanylylimidodiphosphate, produced a rightward shift in the epinephrine competition curve, with resultant increases in both the Ki value and Hill coefficient, suggestive of a functional interaction of the cloned receptor with native guanine nucleotide-binding protein(s) of Ltk- membranes. The data presented here are consistent with previous biochemical and pharmacological studies on alpha 2 receptors and are supportive of the designation of this receptor as an alpha 2B subtype.
Mol Pharmacol 1990 Nov
PMID:Cloning, expression, and pharmacological characterization of a human alpha 2B-adrenergic receptor. 217 75

Poly(A)+ Messenger ribonucleic acid (mRNA) was extracted from leg muscles of the locust Schistocerca gregaria and injected into oocytes of Xenopus laevis. After 5-10 days incubation, receptors for L-glutamate, L-quisqualate, DL-ibotenate and gamma-aminobutyric acid (GABA) were expressed. Agonist-induced currents were dose-dependent, and, in the concentration range 1 microM to 1 mM, generally had peak values of 50 nA. The responses to all agonists, apart from GABA, exhibited desensitization which could not be reversed even by prolonged washing with Ringer. Application of 100 microM GABA to oocytes voltage clamped at -60 mV produced a smooth inward current with a reversal potential of -22 +/- 1 mV, which is consistent with the involvement of chloride ions. At 100 microM, picrotoxin reversibly abolished this current, while 100 microM bicuculline had no effect. L-Glutamate elicited a smooth current with a reversal potential of -52 +/- 3 mV. L-Quisqualate elicited an inward current at -60 mV with a reversal potential of -9 +/- 2 mV; this current occasionally had an oscillatory component. The response to ibotenate comprised a smooth inward current with a reversal potential of -21 +/- 3 mV which was probably mediated by chloride ions.
Brain Res Mol Brain Res 1990 Oct
PMID:Amino acid receptors from insect muscle: electrophysiological characterization in Xenopus oocytes following expression by injection of mRNA. 217 11

Crotalarin, the N-acetyl-D-galactosamine-binding blood group A-specific lectin from the seeds of Crotalaria striata was subjected to various chemical modifications in order to ascertain the amino acid residues responsible for its carbohydrate-binding property. Modification of lysine, cysteine and arginine residues did not affect the carbohydrate-binding activity of the lectin. However, modification of tyrosine residue and carboxy group of the acidic amino acids led to a complete loss of its activity, indicating the involvement of tyrosine and aspartic and glutamic acid in the saccharide-binding respectively. The hemagglutinating activity of the lectin was completely/almost completely lost by modification of tryptophan residues. The relative loss in hemagglutinating activity on modification of tryptophan residues indicate that one residue/molecule is required for the carbohydrate-binding activity of the lectin. Modification was not effective in the presence of D-galactose (0.2 M). A marked decrease in the fluorescence emission was found as the tryptophan residues of crotalarin were modified. The c.d. spectra showed the presence of an identical pattern of conformation in the native and modified lectins which confirms that the loss in activity was due to modification only. The effect of periodate oxidation on crotalarin showed loss of activity whereas action of enzymes retained most of the activity.
Mol Cell Biochem 1990 Aug 10
PMID:Chemical modification studies on a blood group A-specific lectin, crotalarin (Crotalaria striata) and its effect on hemagglutinating activity. 217 41


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