Genomic and proteomic studies on Plesiomonas shigelloides lipopolysaccharide core biosynthesis

Structural Diversity among Edwardsiellaceae Core Oligosaccharides

The Edwardsiella genus presents five different pathogenic species: Edwardsiella tarda, E. anguillarum, E. piscicida, E. hoshinae and E. ictaluri. These species cause infections mainly in fish, but they can also infect reptiles, birds or humans. Lipopolysaccharide (endotoxin) plays an important role in the pathogenesis of these bacteria. For the first time, the chemical structure and genomics of the lipopolysaccharide (LPS) core oligosaccharides of E. piscicida, E. anguillarum, E. hoshinae and E. ictaluri were studied. The complete gene assignments for all core biosynthesis gene functions were acquired. The structure of core oligosaccharides was investigated by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. The structures of E. piscicida and E. anguillarum core oligosaccharides show the presence of →3,4)-L-glycero-α-D-manno-Hepp, two terminal β-D-Glcp, →2,3,7)-L-glycero-α-D-manno-Hepp, →7)-L-glycero-α-D-manno-Hepp, terminal α-D-GlcpN, two →4)-α-D-GalpA, → 3)-α-D-GlcpNAc, terminal β-D-Galp and →5-substituted Kdo. E. hoshinare core oligosaccharide shows only one terminal β-D-Glcp, and instead of terminal β-D-Galp a terminal α-D-GlcpNAc. E. ictaluri core oligosaccharide shows only one terminal β-D-Glcp, one →4)-α-D-GalpA and do not have terminal α-D-GlcpN (see complementary figure).

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

The Complete Structure of the Core Oligosaccharide from Edwardsiella tarda EIB 202 Lipopolysaccharide

The chemical structure and genomics of the lipopolysaccharide (LPS) core oligosaccharide of pathogenic Edwardsiella tarda strain EIB 202 were studied for the first time. The complete gene assignment for all LPS core biosynthesis gene functions was acquired. The complete structure of core oligosaccharide was investigated by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization mass spectrometry MSⁿ, and matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry. The following structure of the undecasaccharide was established: The heterogeneous appearance of the core oligosaccharide structure was due to the partial lack of β-d-Galp and the replacement of α-d-GlcpNAcGly by α-d-GlcpNGly. The glycine location was identified by mass spectrometry.

Rapid and sensitive detection of Plesiomonas shigelloides by cross‑priming amplification of the hugA gene

Plesiomonas shigelloides (P. shigelloides) is implicated as an aetiological agent of human gastroenteritis in humans, for which reliable laboratory detection of P. shigelloides is clinically and epidemiologically desirable. A simple molecular method for rapid detection of P. shigelloides using cross-priming amplification (CPA) has been developed, with hugA as the target. The hugA gene is required for haem iron utilisation and is critical for the survival and growth of P. shigelloides. The assay output was visualised as a colour change with no need to open the reaction tubes, and no false-positive results were detected for the 33 non- P. shigelloides strains examined to assess assay specificity. The limit of detection was 200 fg P. shigelloides DNA per reaction and 3×10³ CFU per g in human stools, which was 100 and 10-fold more sensitive than polymerase chain reaction, respectively. The CPA method was used to detect the presence of P. shigelloides in stool specimens from 70 patients with diarrhoea and 30 environmental water samples, with no difference in accuracy between the CPA assay and the biological culture. The present study, therefore, suggests that the P. shigelloides hugA CPA assay may represent a valuable tool for rapid and sensitive detection of P. shigelloides in primary care facilities and clinical laboratories.

Plesiomonas shigelloides Revisited

After many years in the family Vibrionaceae, the genus Plesiomonas, represented by a single species, P. shigelloides, currently resides in the family Enterobacteriaceae, although its most appropriate phylogenetic position may yet to be determined. Common environmental reservoirs for plesiomonads include freshwater ecosystems and estuaries and inhabitants of these aquatic environs. Long suspected as being an etiologic agent of bacterial gastroenteritis, convincing evidence supporting this conclusion has accumulated over the past 2 decades in the form of a series of foodborne outbreaks solely or partially attributable to P. shigelloides. The prevalence of P. shigelloides enteritis varies considerably, with higher rates reported from Southeast Asia and Africa and lower numbers from North America and Europe. Reasons for these differences may include hygiene conditions, dietary habits, regional occupations, or other unknown factors. Other human illnesses caused by P. shigelloides include septicemia and central nervous system disease, eye infections, and a variety of miscellaneous ailments. For years, recognizable virulence factors potentially associated with P. shigelloides pathogenicity were lacking; however, several good candidates now have been reported, including a cytotoxic hemolysin, iron acquisition systems, and lipopolysaccharide. While P. shigelloides is easy to identify biochemically, it is often overlooked in stool samples due to its smaller colony size or relatively low prevalence in gastrointestinal samples. However, one FDA-approved PCR-based culture-independent diagnostic test system to detect multiple enteropathogens (FilmArray) includes P. shigelloides on its panel. Plesiomonads produce β-lactamases but are typically susceptible to many first-line antimicrobial agents, including quinolones and carbapenems.

The Aeromonas salmonicida Lipopolysaccharide Core from Different Subspecies: The Unusual subsp. pectinolytica

Initial hydridization tests using Aeromonas salmonicida typical and atypical strains showed the possibility of different lipopolysaccharide (LPS) outer cores among these strains. By chemical structural analysis, LPS-core SDS-PAGE gel migration, and functional and comparative genomics we demonstrated that typical A. salmonicida (subsp. salmonicida) strains and atypical subsp. masoucida and probably smithia strains showed the same LPS outer core. A. salmonicida subsp. achromogenes strains show a similar LPS outer core but lack one of the most external residues (a galactose linked α1-6 to heptose), not affecting the O-antigen LPS linkage. A. salmonicida subsp. pectinolytica strains show a rather changed LPS outer core, which is identical to the LPS outer core from the majority of the A. hydrophila strains studied by genomic analyses. The LPS inner core in all tested A. salmonicida strains, typical and atypical, is well-conserved. Furthermore, the LPS inner core seems to be conserved in all the Aeromonas (psychrophilic or mesophilic) strains studied by genomic analyses.

Characterization and cross-protection evaluation of M949_1603 gene deletion Riemerella anatipestifer mutant RA-M1

Riemerella anatipestifer infection causes high mortality for ducks which results in major economic losses in the duck industry. In this study, we identified a mutant strain RA-M1 by Tn4351 transposon mutagenesis, in which the M949_1603 gene encoding glycosyl transferase was inactivated. PCR analysis revealed that M949_1603 gene is specifically existed in R. anatipestifer serotype 1 strains. RA-M1 presented no reactivity to the anti-lipopolysaccharide (LPS) MAb in an indirect ELISA. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) followed by Western blotting demonstrated that RA-M1 LPS had a deficiency in ladder-like binding pattern to rabbit antiserum against R. anatipestifer serotype 1 strain CH3, indicating that the O-antigen structure of RA-M1 was changed. RA-M1 showed significant attenuated virulence in ducks and higher sensitivity to normal duck serum, compared with its parent strain CH3. Furthermore, cross-protection of RA-M1 for R. anatipestifer serotypes 1, 2, and 10 strains was evaluated. Ducks that received two immunizations with inactivated RA-M1 vaccine were 100% protected from challenge with R. anatipestifer serotype 1 strain WJ4, serotype 2 strain Yb2, and serotype 10 strain HXb2. No changes were observed in the liver, heart, or spleen samples from the protected ducks during autopsy and histological examination. Furthermore, vaccination generated high antibody titers of 1:12,800 against serotypes 1, 2, and 10 strains and enhanced production of interleukin 2 (IL-2) and IL-4 in ducks. These results suggested that M949_1603 gene is associated with serotype 1 O-antigen biosynthesis, and mutant RA-M1 could be used as a novel cross-protection vaccine candidate to protect ducks against R. anatipestifer infection.

The polar and lateral flagella from Plesiomonas shigelloides are glycosylated with legionaminic acid

Plesiomonas shigelloides is the unique member of the Enterobacteriaceae family able to produce polar flagella when grow in liquid medium and lateral flagella when grown in solid or semisolid media. In this study on P. shigelloides 302-73 strain, we found two different gene clusters, one exclusively for the lateral flagella biosynthesis and the other one containing the biosynthetic polar flagella genes with additional putative glycosylation genes. P. shigelloides is the first Enterobacteriaceae were a complete lateral flagella cluster leading to a lateral flagella production is described. We also show that both flagella in P. shigelloides 302-73 strain are glycosylated by a derivative of legionaminic acid (Leg), which explains the presence of Leg pathway genes between the two polar flagella regions in their biosynthetic gene cluster. It is the first bacterium reported with O-glycosylated Leg in both polar and lateral flagella. The flagella O-glycosylation is essential for bacterial flagella formation, either polar or lateral, because gene mutants on the biosynthesis of Leg are non-flagellated. Furthermore, the presence of the lateral flagella cluster and Leg O-flagella glycosylation genes are widely spread features among the P. shigelloides strains tested.