Harnessing the acceptor substrate promiscuity of Clostridium botulinum Maf glycosyltransferase to glyco-engineer mini-flagellin protein chimeras

Autor: Sonali Sunsunwal, Aasawari Khairnar, Srikrishna Subramanian, T.N.C. Ramya
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Communications Biology, Vol 7, Iss 1, Pp 1-14 (2024)
Druh dokumentu: article
ISSN: 2399-3642
DOI: 10.1038/s42003-024-06736-y
Popis: Abstract Several bacterial flagellins are O-glycosylated with nonulosonic acids on surface-exposed Serine/Threonine residues by Maf glycosyltransferases. The Clostridium botulinum Maf glycosyltransferase (CbMaf) displays considerable donor substrate promiscuity, enabling flagellin O-glycosylation with N-acetyl neuraminic acid (Neu5Ac) and 3-deoxy-D-manno-octulosonic acid in the absence of the native nonulosonic acid, a legionaminic acid derivative. Here, we have explored the sequence/structure attributes of the acceptor substrate, flagellin, required by CbMaf glycosyltransferase for glycosylation with Neu5Ac and KDO, by co-expressing C. botulinum flagellin constructs with CbMaf glycosyltransferase in an E. coli strain producing cytidine-5’-monophosphate (CMP)-activated Neu5Ac, and employing intact mass spectrometry analysis and sialic acid-specific flagellin biotinylation as readouts. We found that CbMaf was able to glycosylate mini-flagellin constructs containing shortened alpha-helical secondary structural scaffolds and reduced surface-accessible loop regions, but not non-cognate flagellin. Our experiments indicated that CbMaf glycosyltransferase recognizes individual Ser/Thr residues in their local surface-accessible conformations, in turn, supported in place by the secondary structural scaffold. Further, CbMaf glycosyltransferase also robustly glycosylated chimeric proteins constructed by grafting cognate mini-flagellin sequences onto an unrelated beta-sandwich protein. Our recombinant engineering experiments highlight the potential of CbMaf glycosyltransferase in future glycoengineering applications, especially for the neo-O-sialylation of proteins, employing E. coli strains expressing CMP-Neu5Ac (and not CMP-KDO).
Databáze: Directory of Open Access Journals
Nepřihlášeným uživatelům se plný text nezobrazuje