Open AccessUse of Synthetic Glycolipids to Probe the Number and Position of Arabinan Chains on Mycobacterial Arabinogalactan
Author(s) -
Shiva Kumar Angala,
Maju Joe,
Michael McNeil,
Avraham Liav,
Todd L. Lowary,
Mary Jackson
Publication year - 2020
Publication title -
acs chemical biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.899
H-Index - 111
eISSN - 1554-8937
pISSN - 1554-8929
DOI - 10.1021/acschembio.0c00765
Subject(s) - arabinogalactan , galactan , cell wall , peptidoglycan , arabinose , mycobacterium smegmatis , residue (chemistry) , glycolipid , mycobacterium , biochemistry , biology , galactose , stereochemistry , chemistry , fermentation , xylose , bacteria , mycobacterium tuberculosis , medicine , tuberculosis , genetics , pathology
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 (Ara f ) unit of the arabinan domain to the galactan backbone of arabinogalactan, but the number and precise position at which Ara f residue(s) is/are added in mycobacteria remain ill-defined. Using membrane preparations from Mycobacterium smegmatis overexpressing aftA , farnesyl-phospho-arabinose as an Ara f 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.