6GI3

Structure of Lytic Transglycosylase MltE mutant S73A from E.coli

Summary for 6GI3

• Entry DOI: 10.2210/pdb6gi3/pdb
• Descriptor: Endo-type membrane-bound lytic murein transglycosylase A, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL (3 entities in total)
• Functional Keywords: lytic transglycosylase, lyase
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 21520.45

Authors

Batuecas, M.T.,Hermoso, J.A. (deposition date: 2018-05-09, release date: 2018-10-10, Last modification date: 2024-01-17)

Primary citation

Dik, D.A.,Batuecas, M.T.,Lee, M.,Mahasenan, K.V.,Marous, D.R.,Lastochkin, E.,Fisher, J.F.,Hermoso, J.A.,Mobashery, S.
A Structural Dissection of the Active Site of the Lytic Transglycosylase MltE from Escherichia coli.
Biochemistry, 57:6090-6098, 2018

PubMed Abstract: Lytic transglycosylases (LTs) are bacterial enzymes that catalyze the cleavage of the glycan strands of the bacterial cell wall. The mechanism of this cleavage is a remarkable intramolecular transacetalization reaction, accomplished by an ensemble of active-site residues. Because the LT reaction occurs in parallel with the cell wall bond-forming reactions catalyzed by the penicillin-binding proteins, simultaneous inhibition of both enzymes can be particularly bactericidal to Gram-negative bacteria. The MltE lytic transglycosylase is the smallest of the eight LTs encoded by the Escherichia coli genome. Prior crystallographic and computational studies identified four active-site residues-E64, S73, S75, and Y192-as playing roles in catalysis. Each of these four residues was individually altered by mutation to give four variant enzymes (E64Q, S73A, S75A, and Y192F). All four variants showed reduced catalytic activity [soluble wild type (100%) > soluble Y192F and S75A (both 40%) > S73A (4%) > E64Q (≤1%)]. The crystal structure of each variant protein was determined at the resolution of 2.12 Å for E64Q, 2.33 Å for Y192F, 1.38 Å for S73A, and 1.35 Å for S75A. These variants show alteration of the hydrogen-bond interactions of the active site. Within the framework of a prior computational study of the LT mechanism, we suggest the mechanistic role of these four active-site residues in MltE catalysis.

PubMed: 30256085
DOI: 10.1021/acs.biochem.8b00800

Experimental method

X-RAY DIFFRACTION (1.38 Å)