A step-by-step in crystallo guide to bond cleavage and 1,6-anhydro-sugar product synthesis by a peptidoglycan-degrading lytic transglycosylase - Institut Pasteur Access content directly
Journal Articles Journal of Biological Chemistry Year : 2018

A step-by-step in crystallo guide to bond cleavage and 1,6-anhydro-sugar product synthesis by a peptidoglycan-degrading lytic transglycosylase

Muhamed-Kheir Taha

Abstract

Lytic transglycosylases (LTs) are a class of enzymes important for the recycling and metabolism of peptidoglycan (PG). LTs cleave the-1,4-glycosidic bond between N-acetylmuramic acid (MurNAc) and GlcNAc in the PG glycan strand, resulting in the concomitant formation of 1,6-anhydro-N-acetylmuramic acid and GlcNAc. No LTs reported to date have utilized chitins as substrates, despite the fact that chitins are GlcNAc polymers linked via-1,4-glycosidic bonds, which are the known site of chemical activity for LTs. Here, we demonstrate enzymatically that LtgA, a non-canonical, substrate-permissive LT from Neisseria meningitidis utilizes chitopentaose ((GlcNAc) 5) as a substrate to produce three newly identified sugars: 1,6-anhydro-chitobiose, 1,6-anhydro-chitotriose, and 1,6-anhydro-chitotetraose. Although LTs have been widely studied, their complex reactions have not previously been visualized in the crystalline state because macromolecular PG is insoluble. Here, we visualized the cleavage of the glycosidic bond and the liberation of GlcNAc-derived residues by LtgA, followed by the synthesis of atypical 1,6-anhydro-GlcNAc derivatives. In addition to the newly identified anhydro-chitin products , we identified trapped intermediates, unpredicted sub-strate rearrangements, sugar distortions, and a conserved crystallographic water molecule bound to the catalytic gluta-mate of a high-resolution native LT. This study enabled us to propose a revised alternative mechanism for LtgA that could also be applicable to other LTs. Our work contributes to the understanding of the mechanisms of LTs in bacterial cell wall biology.
Fichier principal
Vignette du fichier
6000.full.pdf (1.91 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

pasteur-01950858 , version 1 (11-12-2018)

Licence

Attribution - NonCommercial - ShareAlike

Identifiers

Cite

Allison H Williams, Richard Wheeler, Lesly Rateau, Christian Malosse, Julia Chamot-Rooke, et al.. A step-by-step in crystallo guide to bond cleavage and 1,6-anhydro-sugar product synthesis by a peptidoglycan-degrading lytic transglycosylase. Journal of Biological Chemistry, 2018, 293 (16), pp.6000-6010. ⟨10.1074/jbc.ra117.001095⟩. ⟨pasteur-01950858⟩
45 View
107 Download

Altmetric

Share

Gmail Facebook X LinkedIn More