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Ravikumaran KS, Armiento S, De Castro C, Molinaro A, Wilson JC, Grice ID, Peak IR. Characterisation of a capsular polysaccharide from Moraxella nonliquefaciens CCUG 348T. Carbohydr Res 2024; 538:109095. [PMID: 38507941 DOI: 10.1016/j.carres.2024.109095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/22/2024] [Accepted: 03/14/2024] [Indexed: 03/22/2024]
Abstract
Moraxella nonliquefaciens is a commensal of the human upper respiratory tract (URT) but on rare occasions is recovered in cases of ocular, septic and pulmonary infections. Hence there is interest in the pathogenic determinants of M. nonliquefaciens, of which outer membrane (OM) structures such as fimbriae and two capsular polysaccharide (CPS) structures, →3)-β-D-GalpNAc-(1→5)-β-Kdop-(2→ and →8)-α-NeuAc-(2→, have been reported in the literature. To further characterise its surface virulence factors, we isolated a novel CPS from M. nonliquefaciens type strain CCUG 348T. This structure was elucidated using NMR data obtained from CPS samples that were subjected to various degrees of mild acid hydrolysis. Together with GLC-MS data, the structure was resolved as a linear polymer composed of two GalfNAc residues consecutively added to Kdo, →3)-β-D-GalfNAc-(1→3)-α-D-GalfNAc-(1→5)-α-(8-OAc)Kdop-(2→. Supporting evidence for this material being CPS was drawn from the proposed CPS biosynthetic locus which encoded a potential GalfNAc transferase, a UDP-GalpNAc mutase for UDP-GalfNAc production and a putative CPS polymerase with predicted GalfNAc and Kdo transferase domains. This study describes a unique CPS composition reported in Moraxella spp. and offers genetic insights into the synthesis and expression of GalfNAc residues, which are rare in bacterial OM glycans.
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Affiliation(s)
- Kosala S Ravikumaran
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia
| | - Samantha Armiento
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126, Napoli, Italy
| | - Cristina De Castro
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126, Napoli, Italy
| | - Antonio Molinaro
- Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126, Napoli, Italy
| | - Jennifer C Wilson
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia
| | - I Darren Grice
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia; Institute for Glycomics, Griffith University, Gold Coast Campus, Queensland, 4222, Australia.
| | - Ian R Peak
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia; Institute for Glycomics, Griffith University, Gold Coast Campus, Queensland, 4222, Australia.
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Ravikumaran KS, King RM, Notaro A, Molinaro A, de Castro C, Wilson JC, Grice ID, Peak IR. Moraxella ovis and Moraxella bovoculi lipooligosaccharide biosynthesis genes, and structural characterisation of oligosaccharide from M. ovis 354T. Carbohydr Res 2024; 536:109043. [PMID: 38281396 DOI: 10.1016/j.carres.2024.109043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/16/2024] [Accepted: 01/16/2024] [Indexed: 01/30/2024]
Abstract
Moraxella ovis is a Gram-negative bacterium isolated from sheep conjunctivitis cases and is a rare isolate of infectious bovine keratoconjunctivitis (IBK). This species is closely related to M. bovoculi, another species which can also be isolated from IBK, or cattle upper respiratory tract (URT). Prior to molecular identification techniques, M. bovoculi was frequently misclassified as M. ovis. We previously described the structure of two oligosaccharides (lipooligosaccharide-derived, minor and major glycoforms) from M. bovoculi 237T (type strain, also ATCC BAA-1259T). Here, we have identified the genetic loci for lipooligosaccharide synthesis in M. ovis 354T (NCTC11227) and compared it with M. bovoculi 237T. We identified genes encoding the known glycosyltransferases Lgt6 and Lgt3 in M.ovis. These genes are conserved in Moraxella spp., including M bovoculi. We identified three further putative OS biosynthesis genes that are restricted to M. ovis and M. bovoculi. These encode enzymes predicted to function as GDP-mannose synthases, namely a mannosyltransferase and a glycosyltransferase. Adding insight into the genetic relatedness of M.ovis and M. bovoculi, the M. ovis genes have higher similarity to those in M. bovoculi genotype 2 (nasopharyngeal isolates from asymptomatic cattle), than to M. bovoculi genotype 1 (isolates from eyes of IBK-affected cattle). Sequence analysis confirmed that the predicted mannosyltransferase in M. bovoculi 237T is interrupted by a C>T polymorphism. This mutation is not present in other M. bovoculi strains sequenced to date. We isolated and characterised LOS-derived oligosaccharide from M. ovis 354T. GLC-MS and NMR spectroscopy data revealed a heptasaccharide structure with three β-D-Glcp residues attached as branches to the central 3,4,6-α-D-Glcp, with subsequent attachment to Kdo. This inner core arrangement is consistent with the action of Lgt6 and Lgt3 glycosyltransferases. Two α-D-Manp residues are linearly attached to the 4-linked β-D-Glcp, consistent with the presence of the two identified glycosyltransferases. This oligosaccharide structure is consistent with the previously reported minor glycoform isolated from M. bovoculi 237T.
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Affiliation(s)
- Kosala S Ravikumaran
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia
| | - Rebecca M King
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia
| | - Anna Notaro
- Dipartmento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126, Napoli, Italy
| | - Antonio Molinaro
- Dipartmento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126, Napoli, Italy
| | - Cristina de Castro
- Dipartmento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126, Napoli, Italy
| | - Jennifer C Wilson
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia
| | - I Darren Grice
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia; Institute for Glycomics, Griffith University, Gold Coast Campus, Queensland, 4222, Australia.
| | - Ian R Peak
- School of Pharmacy and Medical Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia; Institute for Glycomics, Griffith University, Gold Coast Campus, Queensland, 4222, Australia.
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Huang YX, Liang J, Chai JH, Kuang HX, Xia YG. Structure of a highly branched galacturonoglucan from fruits of Schisandra chinensis (Turcz.) Baill. Carbohydr Polym 2023; 313:120844. [PMID: 37182946 DOI: 10.1016/j.carbpol.2023.120844] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/14/2023] [Accepted: 03/21/2023] [Indexed: 04/03/2023]
Abstract
A novel galacturonoglucan, named SCP-1, is isolated and purified from Schisandra chinensis fruits. The structure of SCP-1 is systematically investigated by a combination of monosaccharide compositions, absolute Mw, methylation analysis, partial acid hydrolysis, isoamylase degradations, and nuclear magnetic resonance spectroscopy. The structure of SCP-1 is theoretically described as follows: (i) Glc and GalA in a molar ratio of 17:3; (ii) → 4)-α-Glcp-(1→, →4,6)-α-Glcp-(1→, →3,4,6)-α-Glcp-(1→, α-Glcp-(1→, →4)-α-GalAp-6-OMe-(1→, α-GalAp-6-OMe-(1→, β-Glcp-(1→, →6-)-β-Glcp-(1 → and →3,4)-β-Glcp-(1 → in a molar ratio of 48:5:3:3:10:5:12:5:9; (iii) a repeating unit of →4)-α-Glcp-(1 → as a backbone with branched points at C-3 and C-6, substituted by different types of acidic and neutral side chains to form multiple branches; and (iv) a rigid rod configuration deduced from α value of 1.26 in Mark-Houwink equation ([η] = kMα). Anti-tumor assay investigated the effects of SCP-1 on human HepG2 cancer cell lines in vitro. This is for the first time to report a galacturonoglucan in S. chinensis fruits.
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