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bioRxiv · 10.1101/2022.05.02.490363

Discovery and structure of a widespread bacterial ABC transporter specific for ergothioneine

Zhang, Y.·Gonzalez-Gutierrez, G.·Legg, K. A.·Edmonds, K. A.·Giedroc, D. P.
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Abstract

Ergothioneine (ET) is the 2-thiourea derivative of trimethylhistidine that is biosynthesized only by select fungi and bacteria, notably Mycobacterium tuberculosis, and functions as a potent scavenger of reactive oxygen species. Although ET is obtained in the diet and accumulates in vertebrate cells via an ET-specific transporter, the extent to which ET broadly functions in bacterial cells unable to synthesize it is unknown. Here we show that spd_1642-1643 in Streptococcus pneumoniae D39, a Gram-positive respiratory pathogen, encodes a novel ergothioneine uptake ATP-binding cassette (ABC) transporter, which we designate EgtUV. EgtU is a permease-solute binding domain (SBD) fusion protein, and the SBD binds ET with high affinity and exquisite specificity in the cleft between the two subdomains, with cation-{pi} interactions engaging the betaine moiety and a water-mediated hydrogen bonding network surrounding the C2-sulfur-containing imidazole ring. Bioinformatics studies reveal that EgtUV is uniquely strongly conserved among known quaternary amine-specific transporters and widely distributed in firmicutes, including the human pathogens Listeria monocytogenes, as BilEB, Enterococcus faecalis and Staphylococcus aureus. This discovery significantly diversifies the LMW thiol pool in Gram-positive human pathogens that may contribute to antioxidant defenses in the infected host.

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Zhang, Y., Gonzalez-Gutierrez, G., Legg, K. A., Edmonds, K. A., Giedroc, D. P.. 2022-05-03. Discovery and structure of a widespread bacterial ABC transporter specific for ergothioneine. https://doi.org/10.1101/2022.05.02.490363

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