Philip Tatham
@micalis.fr
Paris-Saclay university
INRAE
RESEARCH, TEACHING, or OTHER INTERESTS
Biochemistry, Genetics and Molecular Biology, Structural Biology, Catalysis, Biochemistry (medical)
Scopus Publications
Scopus Publications
Feryel Soualmia, Mickael V. Cherrier, Timothée Chauviré, Mickaël Mauger, Philip Tatham, Alain Guillot, Xavier Guinchard, Lydie Martin, Patricia Amara, Jean-Marie Mouesca,et al.
American Chemical Society (ACS)
PylB is a radical S-adenosyl-l-methionine (SAM) enzyme predicted to convert l-lysine into (3R)-3-methyl-d-ornithine, a precursor in the biosynthesis of the 20 s proteogenic amino acid pyrrolysine. This protein highly resembles that of the radical SAM tyrosine and tryptophan lyases, which activate their substrate by abstracting a H atom from the amino-nitrogen position. Here, combining in vitro assays, analytical methods, electron paramagnetic resonance spectroscopy, and theoretical methods, we demonstrated that instead, PylB activates its substrate by abstracting a H atom from the Cγ position of l-lysine to afford the radical-based β-scission. Strikingly, we also showed that PylB catalyzes the reverse reaction, converting (3R)-3-methyl-d-ornithine into l-lysine and using catalytic amounts of the 5'-deoxyadenosyl radical. Finally, we identified significant in vitro production of 5'-thioadenosine, an unexpected shunt product that we propose to result from the quenching of the 5'-deoxyadenosyl radical species by the nearby [Fe4S4] cluster.