Biology subjects

Ojuri, T. O.

Publications and source records attributed to Ojuri, T. O..

3 recordsLinked to original sources

bioRxiv2025

PNGaseA-mediated N-glycan stripping from peptides by infant-derived Bifidobacterium bifidum

N-glycans are highly common sources of nutrition for human colonic-dwelling bacteria. These microbes have evolved a several methods to remove N-glycans from proteins; herein we describe the biochemical and structural characterisation of one such enzyme, a PNGaseA superfamily member produced by the infant-associated Bifidobacterium bifidum LMG13195. This PNGase was demonstrated to elicit activity against a wide variety of N-glycan structures yet exhibited a high preference for N-glycans attached to a peptide rather than to a denatured or native protein. This unusual specificity highlights how bacterial species tune their enzymology to different types of substrates. The structural characterisation of this PNGase reveals how its structure determines this specificity while being the first structure presented from the PNGaseA superfamily, revealing a unique ten-stand {beta}-sheet cradling a canonical PNGase catalytic module.

biochemistry↗

bioRxiv2025

PNGaseL from Flavobacterium akiainvivens targets a diverse range of N-glycan structures

PNGases are used by a wide range of organisms to remove N-glycan structures from proteins for use as either nutrients or in glycoprotein processing. PNGaseF is the most well-characterised enzyme of this family and is widely used in glycobiology to allow study of the N-glycome of a specific protein, cell and tissues, for instance. Despite this, PNGaseF has limitations in the types of N-glycan structures it can target. In this study, we explored the specificities of six uncharacterised PNGases selected from diverse parts of the PNGaseF superfamily. One of these enzymes, PNGaseL from Flavobacterium akiainvivens, is the highlight of this study due to its very broad specificity exemplified by its ability to cleave mammalian-, plant- and invertebrate-type complex N-glycans as well as high-mannose N-glycans. A detailed biochemical and structural characterisation was carried out against a variety of substrates to illustrate the advanced capability of PNGaseL in comparison to the canonical PNGaseF and PNGaseA enzymes. To determine the optimal reaction conditions, assess stability and define limitations of PNGaseL, a series of validation studies was performed. The data reveal that PNGaseL has potential utility in a range of glycobiology applications that are superior to the current commercially available options.

biochemistry↗

bioRxiv2024

Carbohydrate-active enzymes from Akkermansia muciniphila breakdown mucin O-glycans to completion

Akkermansia muciniphila is a human microbial symbiont residing in the mucosal layer of the large intestine. Its main carbon source is the highly heterogeneous mucin glycoprotein and A. muciniphila uses an array of Carbohydrate-active enzymes and sulfatases to access this complex energy source. Here we describe the biochemical characterisation of fifty-four glycoside hydrolases, eleven sulfatases, and one polysaccharide lyase from A. muciniphila to provide a holistic understanding of the carbohydrate-degrading activities. The results provide an extensive insight into the sequence of O-glycan degradation and how A. muciniphila can access this structurally variable substrate. One of the most outstanding elements of this work was the demonstration that these enzymes can act synergistically to degrade the O-glycans on the mucin polypeptide to completion, down to the core GalNAc. Additionally, human breast milk oligosaccharide, ganglioside, and globoside glycan structures were included in the study to understand the full degradative capability of A. muciniphila.

biochemistry↗