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Bell, Andrew, Severi, Emmanuele, Lee, Micah O., Monaco, Serena, Latousakis, Dimitrios, Angulo, Jesus 
ORCID: https://orcid.org/0000-0001-7250-5639, Thomas, Gavin H., Naismith, James H. and Juge, Nathalie
(2020)
Uncovering a novel molecular mechanism for scavenging sialic acids in bacteria.
The Journal of Biological Chemistry, 295 (40).
pp. 13724-13736.
ISSN 0021-9258
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Abstract
The human gut symbiont Ruminococcus gnavus scavenges host-derived N-acetylneuraminic acid (Neu5Ac) from mucins by converting it to 2,7-anhydro-Neu5Ac. We previously showed that 2,7-anhydro-Neu5Ac is transported into R. gnavus ATCC 29149 before being converted back to Neu5Ac for further metabolic processing. However, the molecular mechanism leading to the conversion of 2,7-anhydro-Neu5Ac to Neu5Ac remained elusive. Using 1D and 2D NMR, we elucidated the multistep enzymatic mechanism of the oxidoreductase (RgNanOx) that leads to the reversible conversion of 2,7-anhydro-Neu5Ac to Neu5Ac through formation of a 4-keto-2-deoxy-2,3-dehydro-N-acetyl-neuraminic acid intermediate and NAD 1 regeneration. The crystal structure of RgNanOx in complex with the NAD 1 cofactor showed a protein dimer with a Rossman fold. Guided by the RgNanOx structure, we identified catalytic residues by site-directed mutagenesis. Bioinformatics analyses revealed the presence of RgNanOx homologues across Gram-negative and Gram-positive bacterial species and co-occurrence with sialic acid transporters. We showed by electrospray ionization spray MS that the Escherichia coli homologue YjhC displayed activity against 2,7-anhydro-Neu5Ac and that E. coli could catabolize 2,7-anhydro-Neu5Ac. Differential scanning fluorimetry analyses confirmed the binding of YjhC to the substrates 2,7-anhydro-Neu5Ac and Neu5Ac, as well as to co-factors NAD and NADH. Finally, using E. coli mutants and complementation growth assays, we demonstrated that 2,7-anhydro-Neu5Ac catabolism in E. coli depended on YjhC and on the predicted sialic acid transporter YjhB. These results revealed the molecular mechanisms of 2,7-anhydro-Neu5Ac catabolism across bacterial species and a novel sialic acid transport and catabolism pathway in E. coli.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 2,7-anhydro-neu5ac,2,7-anhydro-neu5ac,escherichia coli,escherichia coli (e. coli),ruminococcus gnavus,std nmr,gut microbiota,gut symbiosis,microbiology,mucin glycosylation,nuclear magnetic resonance (nmr),oxidation-reduction (redox),oxidoreductase,sialic acid,sialic acid transporters,symbiosis,biochemistry,molecular biology,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1303 |
| Faculty \ School: | Faculty of Science > School of Biological Sciences Faculty of Science > School of Pharmacy (former - to 2024) Faculty of Medicine and Health Sciences > Norwich Medical School |
| UEA Research Groups: | Faculty of Science > Research Groups > Pharmaceutical Materials and Soft Matter |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 13 Aug 2020 23:58 |
| Last Modified: | 17 Oct 2024 00:21 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/76432 |
| DOI: | 10.1074/jbc.RA120.014454 |
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