PDBsum entry 5o2n

Hydrolase

PDB id: 5o2n

Contents

Protein chain

577 a.a.

Ligands

NDG-NAG-NAG-NAG

NAG

FLC

Waters ×1048

PDB id:

5o2n

Name:

Hydrolase

Title:

Lytic transglycosylase in action

Structure:

Transglycosylase. Chain: a. Engineered: yes

Source:

Neisseria meningitidis. Organism_taxid: 487. Gene: slt, ers514729_01258. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693. Expression_system_variant: gold

Resolution:

1.51Å R-factor: 0.163 R-free: 0.192

Authors:

A.H.Williams,A.Hoauz,I.G.Boneca

Key ref:

A.H.Williams et al. (2018). A step-by-step J Biol Chem, 293, 6000-6010. PubMed id: 29483188

Date:

22-May-17 Release date: 14-Mar-18

Supersedes:

4yp4

Protein chain

Q9JXP1  (Q9JXP1_NEIMB) -  Soluble lytic murein transglycosylase from Neisseria meningitidis serogroup B (strain ATCC BAA-335 / MC58)

Seq: 616 a.a.

Struc: 577 a.a.

Enzyme reactions

• Enzyme class: E.C.4.2.2.- - ?????

J Biol Chem 293:6000-6010 (2018)

PubMed id: 29483188

A step-by-step

A.H.Williams, R.Wheeler, L.Rateau, C.Malosse, J.Chamot-Rooke, A.Haouz, M.K.Taha, I.G.Boneca.

ABSTRACT

Lytic transglycosylases (LTs) are a class of enzymes important for the recycling and metabolism of peptidoglycan (PG). LTs cleave the β-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 β-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 substrate rearrangements, sugar distortions, and a conserved crystallographic water molecule bound to the catalytic glutamate 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.