O polysaccharides (OPS) of the lipopolysaccharides (LPS) of Pseudomonas syringae pathovar tomato GSPB 483 and pathovar maculicola IMV 381 were studied by 1 H-NMR and 13 C-NMR spectroscopy, including two-dimensional COSY, rotating-frame NOE spectroscopy (ROESY), and H-detected 1 H, 13 C heteronuclear multiple-quantum coherence (HMQC) experiments. The OPS from both strains were shown to be chemically identical. Two structurally different types of repeating units (O repeats 1 and 2) were elucidated in each OPS. The minor O repeat is a pentasaccharide having the structure 2. The same structure has been reported earlier for some other OPS of P. syringae. The major O repeat is a hexasaccharide with the novel structure 1 which is distinguished from 2 by the presence of the second lateral residue of 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc) and by a different position of substitution of one of the L-rhamnose (Rha) residues in the backbone.Structural and serological diversity of OPS of strains belonging to P. syringae pv. tomato and pv. maculicola and phylogenetic relatedness of the strains are discussed. Immunochemical studies of LPS of P. syringae revealed correlation between the chemical structures of OPS and the specificity of mAbs against various strains of P. syringae [5Ϫ8]. These findings enabled us to shed some light on the molecular basis of the immunospecificity of P. syringae LPS and to infer the serogroup-specific and serotype-specific OPS-associated epitopes. One of the mAbs, Ps4e 1 (formerly Ps4a), produced against P. syringae pv. syringae (holci) IMV 8300, was shown to be specific in ELISA [8] to OPS with pentasaccharide O repeats containing four L-Rha residues in the backbone and one lateral residue of 3-acetamido-3,6-dideoxy-D-galactose (D-Fuc3NAc) (structure 3) [2]. This LPS phenotype is characterised by the serological formula O4a,4e,4e 1 . However, mAb Ps4e 1 did not
Transfer of plasmid pRD1 from Escherichia coli K 12J62 -1 to phytopathogenic bacteria, Agrobacterium tumefaciens, Xanthomonas beticola and Erwinia carotovora subsp. carotovora caused changes in conjugant properties not determined by the plasmid and the emergence of the properties not present in the parent strains. Clones have been obtained with intermediate properties between donor and recipient, including those with altered or lost virulence. In transconjugants of A. tumefaciens virulence increased. In transconjugants of X. beticola and E. carotovora subsp. carotovora highly virulent as well as avirulent forms have been observed. The loss of virulence in X. beticola correlated with the Nif+ phenotype. Plasmid pRD1 also affected the biochemical properties of the new hosts.
Вплив ліпополісахариду Pseudomonas syringae pv. atrofaciens на спонтанні та індуковані біхроматом калію мутації у Salmonella typhimurium Л. М. Ващенко, Л. А. Пасічник, P. І. Гвоздяк Інститут мікробіології і вірусології ім. Д. К. Заболотного НАН України Вул. Академіка Заболотного, 154, Київ, 03143, Україна Виявлено, що ліпополісахарид (ЛПС) P. syringae pv. atrofaciens 8281 у дозі 1000 мкг на чашку зменшує частоту спонтанних мутацій S. typhimurium ТА98 на ЗІ %, S. typhimurium TAJ00 -на 16 %. Досліджуваний ЛПС виявив антимутагенні властивості і стосовно індукованих біхроматом калію мутацій. Частота таких мутацій зменшувалася залежно від дози ЛПС на 57-78 % для тест-штаму S. typhimurium ТА98, та на 14-49 % -для S. typhimurium ТА 100.
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