Human gut microbes express functionally distinct endoglycosidases to metabolize the same N-glycan substrate.
SASTRE, Diego Emiliano; SULTANA, Nazneen; NAVARRO, Marcos Vicente de Albuquerque Salles; HULICIAK, Maros; DU, Jonathan; CIFUENTE, Javier Orlando; FLOWERS, Maria; LIU, Xiu; LOLLAR, Pete; TRASTOY, Beatriz; GUERIN, Marcelo E.; SUNDBERG, Eric J.
SASTRE, Diego Emiliano; SULTANA, Nazneen; NAVARRO, Marcos Vicente de Albuquerque Salles; HULICIAK, Maros; DU, Jonathan; CIFUENTE, Javier Orlando; FLOWERS, Maria; LIU, Xiu; LOLLAR, Pete; TRASTOY, Beatriz; GUERIN, Marcelo E.; SUNDBERG, Eric J.
Abstract: Bacteroidales (syn. Bacteroidetes) are prominent members of the human gastrointestinal ecosystem mainly due to their efficient glycan-degrading machinery, organized into gene clusters known as polysaccharide utilization loci (PULs). A single PUL was reported for catabolism of high-mannose (HM) Nglycan glyco-polypeptides in the gut symbiont Bacteroides thetaiotaomicron, encoding a surface endo-ß-N-acetylglucosaminidase (ENGase), BT3987. Here, we discover an ENGase from the GH18 family in B. thetaiotaomicron, BT1285, encoded in a distinct PUL with its own repertoire of proteins for catabolism of the same HM N-glycan substrate as that of BT3987. We employ X-ray crystallography, electron microscopy, mass spectrometry-based activity measurements, alanine scanning mutagenesis and a broad range of biophysical methods to comprehensively define the molecular mechanism by which BT1285 recognizes and hydrolyzes HM N-glycans, revealing that the stabilities and activities of BT1285 and BT3987 were optimal in markedly different conditions. BT1285 exhibits significantly higher affinity and faster hydrolysis of poorly accessible HM N-glycans than does BT3987. We also find that two HMprocessing endoglycosidases from the human gut-resident Alistipes finegoldii display condition-specific functional properties. Altogether, our data suggest that human gut microbes employ evolutionary strategies to express distinct ENGases in order to optimally metabolize the same N-glycan substrate in the gastroinstestinal tract.
@article={003237031,author = {SASTRE, Diego Emiliano; SULTANA, Nazneen; NAVARRO, Marcos Vicente de Albuquerque Salles; HULICIAK, Maros; DU, Jonathan; CIFUENTE, Javier Orlando; FLOWERS, Maria; LIU, Xiu; LOLLAR, Pete; TRASTOY, Beatriz; GUERIN, Marcelo E.; SUNDBERG, Eric J.},title={Human gut microbes express functionally distinct endoglycosidases to metabolize the same N-glycan substrate},journal={Nature Communications},note={v. 15, p. 5123-1-5123-17},year={2024}}