Molecular mechanism of elongation factor 1A inhibition by a Legionella pneumophila glycosyltransferase

Ramon Hurtado-Guerrero , Tal Zusman , Shalini Pathak , Adel F.M. Ibrahim , Sharon Shepherd , Alan Prescott , Gil Segal , Daan M.F. van Aalten (1)

1 Wellcome Trust Biocentre,

Legionnaires' disease is caused by a lethal colonization of alveolar macrophages with the Gram negative bacterium Legionella pneumophila. An L. pneumophila glucosyltransferase (LpGT or Lgt1) has recently been identified as a virulence factor, shutting down protein synthesis in the human cell by specific glucosylation of elongation factor 1A (EF1A), using an unknown mode of substrate recognition, and retaining glycosyl transfer. We have determined the crystal structure of LpGT in complex with substrates, revealing a GT-A fold with two unusual protruding domains. Through structure-guided mutagenesis of LpGT, several residues essential for binding of the UDP-glucose donor and EF1A acceptor substrates were identified, also affecting L. pneumophila virulence as demonstrated by microinjection studies. Together, these data suggest that a positively charged EF1A loop binds in a negatively charged, conserved groove on the LpGT structure, and that two asparagines are essential for catalysis. Furthermore, we show that two further L. pneumophila glycosyltransferases, that possess conserved UDP-glucose binding sites and EF1A binding grooves, are, like LpGT, translocated into the macrophage through the Icm/Dot system.

Mots clés: Life Sciences

Ramon Hurtado-Guerrero, Tal Zusman, Shalini Pathak, Adel F.M. Ibrahim, Sharon Shepherd, et al.. Molecular mechanism of elongation factor 1A inhibition by a Legionella pneumophila glycosyltransferase. Biochemical Journal, 2010, 426 (3), pp.281-292. ⟨10.1042/BJ20091351⟩. ⟨hal-00479249⟩