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The completc DNA scqucnccs coding for thc thiol-activated cytolysins from Listeria ivanovii, ivanolysin 0 (ILO) and for sccligerolysin 0 (LSO) from Listeria seeligeri have been dctermined. Thc deduced amino acid scquences revealed that: (i) the primary translation products comprise 528 (ILO) and 530 (LSO) amino acids. respectively. (ii) ILO contains two cysteines. LSO has a substitution in the conserved cysteine motif.
A gene (Imsod) encoding superoxide dismutase (SOD; EC 1.15.1.1) of the facultative intracellular pathogen, Listeria monocytogenes, was cloned by functional complementation of an SOD-deficient Escherichia coli mutant. The nucleotide sequence was determined and the deduced amino acid (aa) sequence (202 aa) showed close similarity to manganese-containing SOD's from other organisms. Subunits of the recombinant L. monocytogenes SOD (re-SOD) and of both E. coli SODs formed enzymatically active hybrid enzymes in vivo. DNA/DNA-hybridization experiments showed that this type of recombinant re-sod gene is conserved within the genus Listeria.
The homology screening approach has been used to clone a new member of the guanine-nucleotidebinding-protein-coupled receptor superfamily from guinea pig uterus. The cloned cDNA encodes a 399-amino-acid protein and shows the highest amino acid similarity to members of the bombesin receptor family; 52% and 47% similarity to the gastrin-releasing-peptide (GRP) receptor and the neuromedin-B receptor, respectively. Bindingexperiments with the stably transfected LLC-PK<sub>1</sub> cell line expressing the new receptor protein confmned the bombesin-like nature of the cloned receptor. The relative order ofligand affinity, GRP = neuromedin C >> neuromedin B, suggests that the cloned cDNA represents the GRP subtype rather than the neuromedin-B subtype of bombesin receptors. Northern-blot analysis of mRNA species from several guinea-pig tissues showed that the mRNA for the new bombesin receptor subtype is expressed mainly in uteri of pregnant animals.
A cDNA encoding guinea-pig uterine substance P (SP) receptor has been isolated using the homology screening approach. Northern blot analysis reveals that the corresponding mRNA, of approx. 4.8 kb, is expressed in all tissues tested, but predominantly in the uteri of non-pregnant animals; during pregnancy its expression is reduced. The guinea-pig SP receptor was expressed in COS-7 cells and demonstrated relative Iigand affinity in the order: SP >> neurokinin A > neurokinin B.