Use of Synthetic Glycolipids to Probe the Number and Position of Arabinan Chains on Mycobacterial Arabinogalactan

Autor: Avraham Liav, Michael R. McNeil, Todd L. Lowary, Shiva K. Angala, Maju Joe, Mary Jackson
Rok vydání: 2020
Předmět:
Zdroj: ACS Chem Biol
ISSN: 1554-8937
1554-8929
DOI: 10.1021/acschembio.0c00765
Popis: The arabinogalactan of Corynebacterianeae is a critical heteropolysaccharide that tethers outer membrane mycolic acids to peptidoglycan thus forming the characteristic cell wall core of these prokaryotes. An essential α-(1→5)-arabinosyltransferase, AftA, is responsible for the transfer of the first arabinofuranosyl (Araf) unit of the arabinan domain to the galactan backbone of arabinogalactan, but the number and precise position at which Araf residue(s) is/are added in mycobacteria remain ill-defined. Using membrane preparations from Mycobacterium smegmatis overexpressing aftA, farnesyl-phospho-arabinose as an Araf donor, and a series of synthetic galactan acceptors of various lengths, we here show that a single priming arabinosyl residue substitutes the C-5 position of a precisely positioned internal 6-linked galactofuranosyl residue of the galactan acceptors, irrespective of their length. This unexpected result suggests that, like the structurally related mycobacterial lipoarabinomannans, the arabinogalactan of mycobacteria may in fact harbor a single arabinan chain.
Databáze: OpenAIRE