Molecular analysis of an enigmatic Streptococcus pneumoniae virulence factor: The raffinose-family oligosaccharide utilization system

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dc.contributor.authorHobbs, Joanne K.
dc.contributor.authorMeier, Edward P. W.
dc.contributor.authorPluvinage, Benjamin
dc.contributor.authorMey, Mackenzie A.
dc.contributor.authorBoraston, Alisdair B.
dc.date.accessioned2021-01-29T19:11:37Z
dc.date.available2021-01-29T19:11:37Z
dc.date.copyright2019en_US
dc.date.issued2019
dc.description.abstractStreptococcus pneumoniae is an opportunistic respiratory pathogen that can spread to other body sites, including the ears, brain, and blood. The ability of this bacterium to break down, import, and metabolize a wide range of glycans is key to its virulence. Intriguingly, S. pneumoniae can utilize several plant oligosaccharides for growth in vitro, including raffinose-family oligosaccharides (RFOs, which are α-(1→6)-galactosyl extensions of sucrose). An RFO utilization locus has been identified in the pneumococcal genome; however, none of the proteins encoded by this locus have been biochemically characterized. The enigmatic ability of S. pneumoniae to utilize RFOs has recently received attention because mutations in two of the RFO locus genes have been linked to the tissue tropism of clinical pneumococcal isolates. Here, we use functional studies combined with X-ray crystallography to show that although the pneumococcal RFO locus encodes for all the machinery required for uptake and degradation of RFOs, the individual pathway components are biochemically inefficient. We also demonstrate that the initiating enzyme in this pathway, the α-galactosidase Aga (a family 36 glycoside hydrolase), can cleave α-(1→3)-linked galactose units from a linear blood group antigen. We propose that the pneumococcal RFO pathway is an evolutionary relic that is not utilized in this streptococcal species and, as such, is under no selection pressure to maintain binding affinity and/or catalytic efficiency. We speculate that the apparent contribution of RFO utilization to pneumococcal tissue tropism may, in fact, be due to the essential role the ATPase RafK plays in the transport of other carbohydrates.en_US
dc.description.reviewstatusRevieweden_US
dc.description.scholarlevelFacultyen_US
dc.identifier.citationHobbs, J. K., Meier, E. P. W., Pluvinage, B., Mey, M. A., & Boraston, A. B. (2019). Molecular analysis of an enigmatic Streptococcus pneumoniae virulence factor: The raffinose-family oligosaccharide utilization system. Journal of Biological Chemistry, 294(46), 17197-17208. https://doi.org/10.1074/jbc.RA119.010280.en_US
dc.identifier.urihttps://doi.org/10.1074/jbc.RA119.010280
dc.identifier.urihttp://hdl.handle.net/1828/12626
dc.language.isoenen_US
dc.publisherJournal of Biological Chemistryen_US
dc.subjectglycoside hydrolaseen_US
dc.subjecthost-pathogen interactionen_US
dc.subjectStreptococcusen_US
dc.subjectstructure-functionen_US
dc.subjectX-ray crystallographyen_US
dc.subjectvirulence factoren_US
dc.subjectgalactosidaseen_US
dc.subjectpneumococcusen_US
dc.subjectraffinose-family oligosaccharide (RFO)en_US
dc.titleMolecular analysis of an enigmatic Streptococcus pneumoniae virulence factor: The raffinose-family oligosaccharide utilization systemen_US
dc.typeArticleen_US

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