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First insights of peptidoglycan amidation in Gram-positive bacteria - the high-resolution crystal structure of Staphylococcus aureus glutamine amidotransferase GatD

DOI: 10.1038/s41598-018-22986-3 DOI Help

Authors: Francisco Leisico (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa) , Diana V. Vieira (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa; Oxford Protein Production Facility) , Teresa A. Figueiredo (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa; Instituto de Tecnologia Química e Biológica António Xavier da Universidade Nova de Lisboa) , Micael Silva (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa) , Eurico J. Cabrita (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa) , Rita G. Sobral (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa) , Ana Madalena Ludovice (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa) , Jose Trincao (Diamond Light Source) , Maria João Romão (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa) , Hermínia De Lencastre (Instituto de Tecnologia Química e Biológica António Xavier da Universidade Nova de Lisboa; The Rockefeller University) , Teresa Santos-silva (Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Scientific Reports , VOL 8

State: Published (Approved)
Published: March 2018

Open Access Open Access

Abstract: Gram-positive bacteria homeostasis and antibiotic resistance mechanisms are dependent on the intricate architecture of the cell wall, where amidated peptidoglycan plays an important role. The amidation reaction is carried out by the bi-enzymatic complex MurT-GatD, for which biochemical and structural information is very scarce. In this work, we report the first crystal structure of the glutamine amidotransferase member of this complex, GatD from Staphylococcus aureus, at 1.85 Å resolution. A glutamine molecule is found close to the active site funnel, hydrogen-bonded to the conserved R128. In vitro functional studies using 1H-NMR spectroscopy showed that S. aureus MurT-GatD complex has glutaminase activity even in the absence of lipid II, the MurT substrate. In addition, we produced R128A, C94A and H189A mutants, which were totally inactive for glutamine deamidation, revealing their essential role in substrate sequestration and catalytic reaction. GatD from S. aureus and other pathogenic bacteria share high identity to enzymes involved in cobalamin biosynthesis, which can be grouped in a new sub-family of glutamine amidotransferases. Given the ubiquitous presence of GatD, these results provide significant insights into the molecular basis of the so far undisclosed amidation mechanism, contributing to the development of alternative therapeutics to fight infections.

Journal Keywords: NMR spectroscopy; Pathogens; X-ray crystallography

Subject Areas: Biology and Bio-materials, Chemistry, Medicine


Instruments: I02-Macromolecular Crystallography , I04-Macromolecular Crystallography

Documents:
s41598-018-22986-3.pdf