Biology subjects

Mathew, C.

Publications and source records attributed to Mathew, C..

3 recordsLinked to original sources

bioRxiv2025

DMB labelling for detection and analysis of capsular polysaccharides

Bacterial capsules are major virulence factors enabling systemic infection by undermining innate and adaptive immunity. Capsular polysaccharides are also the antigen in some of the most successful antibacterial vaccines - including the pneumococcal, neisserial and Hib conjugate vaccines. However, it remains exceptionally challenging to study capsules, primarily due to their high chemical diversity and the limited methods available for their detection and analysis. We describe a robust biochemical method for detection and analysis of ABC transporter-dependent capsular polysaccharides, a major class of capsules that are associated with extraintestinal pathogenic Escherichia coli (ExPEC). The method involves release and fluorescent tagging of polysaccharides from the cell surface. Anion exchange chromatography of labelled samples reveals the presence, relative abundance, and length-distribution of these diverse polysaccharide antigens. The method provides a modern approach to detecting the capsule phenotype, bridging a critical gap left by the decline of serotyping assays. It will enhance our understanding of fundamental capsule biology and advance the development of capsule-targeting vaccines.

biochemistry↗

bioRxiv2020

Glycan-Protein Interactions Determine Kinetics of N-Glycan Remodeling

A hallmark of N-linked glycosylation in the secretory compartments of eukaryotic cells is the sequential remodeling of an initially uniform oligosaccharide to a site-specific, heterogeneous ensemble of glycostructures on mature proteins. To understand site-specific processing, we used protein disulfide isomerase (PDI), a model protein with five glycosylation sites, for molecular dynamics (MD) simulations and compared the result to a biochemical in vitro analysis with four different glycan processing enzymes. As predicted by an analysis of the accessibility of the N-glycans for their processing enzymes derived from the MD simulations, N-glycans at different glycosylation sites showed different kinetic properties for the processing enzymes. In addition, altering the tertiary structure context of N-glycan substrates affected N-glycan remodeling in a site-specific way. We propose that differential, tertiary structure context dependent N-glycan reactivities lead to different glycan structures in the same protein through kinetically controlled processing pathways.

biochemistry↗

bioRxiv2020

Brucella species circulating in wildlife in Serengeti ecosystem, Tanzania

BackgroundBrucellosis is a bacterial zoonosis of public health and economic importance world-wide. It affects a number of domestic animals, wildlife and humans. This study was carried out to determine circulating Brucella species in wildlife in Serengeti ecosystem using molecular techniques. MethodologyA total of 189 samples including EDTA blood, serum and amniotic fluid from buffalos, lions, wildebeest, impala, zebra and hyena that were collected in relation to different cross-sectional studies conducted in the Serengeti ecosystem in Tanzania were used. Multiplex polymerase chain reaction AMOS-PCR and quantitative Real-Time PCR (qPCR) targeting the genus specific surface protein bcsp31 gene and the insertion sequence IS711 element downstream of the alkB gene for B. abortus and BMEI1162 gene for B. melitensis were employed on the samples. ResultsResults indicated that out of 189 samples examined, 12 (6.4%) and 22 (11.6%) contained Brucella DNA as detected by AMOS-PCR and qPCR, respectively. Most of the positive samples were from lions (52.6%) and buffaloes (19.6%). Other animals that were positive included wildebeest, impala, zebra and hyena. Out of 22 positive samples, 16 (66.7%) were identified as B. abortus and the rest were B. melitensis. ConclusionDetection of zoonotic Brucella species in wildlife suggests that livestock and humans at the interface areas where there is high interaction are at risk of acquiring the infection. Therefore, public education to interrupt risky transmission practices is needed. The findings also shed light on the transmission dynamics around interface areas and the role of wildlife in transmission and maintenance of Brucella infection in the region.

microbiology↗