Amnimonas aquatica gen. nov., sp. nov., Isolated from a Freshwater River.

A gram-stain-negative and strictly aerobic bacterium, designated strain HR-ET, was isolated from a water sample of the Han River in South Korea. Cells were catalase-negative and oxidase-positive motile rods with a flagellum. The strain grew at 10-37 °C and pH 7-8 and in the presence of 0-2% (w/v) NaCl. Ubiquinone-8 and summed features 3 (comprising C16:1ω7c and/or C16:1ω6c) and 8 (comprising C18:1ω7c and/or C18:1ω6c), C16:0, iso-C10:0 and C12:0 3-OH were identified as the major respiratory quinone and fatty acids (>5%), respectively. The 16S rRNA gene sequence of strain HR-ET shared the highest similarities with Perlucidibaca piscinae IMCC 1704T (98.1%), Perlucidibaca aquatica BK296T (96.8%), Paraperlucidibaca baekdonensis RL-2T (95.8%) and Paraperlucidibaca wandonensis WT-RY4T (95.7%). However, strain HR-ET formed a phylogenetic lineage distinct from members of the family Moraxellaceae, and a taxonomic analysis by RDP Naïve Bayesian rRNA Classifier classified strain HR-ET as a new genus of the family Moraxellaceae. In addition, analyses based on rpoD, secA and gyrB gene sequences also showed that strain HR-ET formed a lineage distinct from those of the genera Perlucidibaca and Paraperlucidibaca. Average nucleotide identity and in silico DNA-DNA hybridization values between strain HR-ET and the type strains of P. piscinae and P. aquatica were very low with 80.1 and 23.6% and 75.7 and 21.2%, respectively. The DNA G+C content was 67.0 mol%. Based on the phenotypic, genotypic and chemotaxonomic analyses, strain HR-ET represents a novel genus of the family Moraxellaceae, for which the name Amnimonas aquatica gen. nov., sp. nov. is proposed. The type strain of the type species is HR-ET (=KACC 19408T=JCM 32266T).

Characterization of acetylated histidine b1-ion structure: A competition between oxazolone and side chain imidazole moiety.

The detection of post-translational modifications of proteins is an important comprehensive research area. Over the years, proteomic studies involving protein acetylation have attracted a great deal of attention. In the present study, we have focussed on the acetylation of histidine and the intrinsic stability of b1-ion of oxazolone ring and/or with side chain imidazole bicyclic product. The formation of oxazolone structure may occur when an amino moiety undergoes acetylation reaction and when it is present in the vicinity of the side chain imidazole moiety. Tryptic peptides generated from the proteins of Acenitobacter radioresistens MMC5-containing N-terminal histidine were explored in a standard proteomic workflow. Formation of [Formula: see text] ion with an oxazolone ring in these peptides has been supported by a tandem mass spectrometric study of a synthetic peptide and density functional theory calculations. The results obtained from this study have implications in understanding the fragmentation of the peptides generated in the proteomic workflows.

Synthesis of 5-O-oligoglucosyl extended α-(2→4)-Kdo disaccharides corresponding to inner core fragments of Moraxellaceae lipopolysaccharides.

The heptose-deficient inner core of the lipopolysaccharide of several pathogenic strains of the Moraxellaceae family (Moraxella, Acinetobacter) and of Bartonella henselae, respectively, comprises an α-D-glucopyranose attached to position 5 of Kdo. In continuation of the synthesis of fragments of Acinetobacter haemolyticus LPS, the branched α-Glcp-(1 → 5)[α-Kdo-(2 → 4)]-α-Kdo trisaccharide motif was elaborated. The glycosylation of a suitably protected, α-(2 → 4)-interlinked Kdo-disaccharide was achieved in high yield and fair anomeric selectivity using a 4,6-O-benzylidene N-phenyltrifluoroacetimidate glucosyl donor. Subsequent regioselective reductive benzylidene opening afforded a trisaccharide acceptor, which was extended with ß-D-glucopyranosyl and isomaltosyl residues. Global deprotection provided tri- to pentasaccharide structures corresponding to the inner core region of A. haemolyticus lipopolysaccharide.