“…The N-terminal V-set Ig domain in the Siglec family contains common structural determinants, such as a conserved arginine in the F strand, key residue for the formation of salt bridge with the carboxyl group of sialic acid. 22,35,36 As for the Siglec-like adhesins SLBR-H and SLBR-B, despite the proximity in the binding site of arginine residues (Arg340 SLBR-H and Arg484 SLBR-B ) to the sialic acid unit of the ligands, no similar ionic interactions with the carboxyl group of Neu5Ac were detected, but important hydrogen bonds were found with the glycerol moiety, in particular with O8 and O9 of Neu5Ac. Instead, the carboxylate group of Neu5Ac established interactions with the threonine residue of the ΦTRY motif (Thr339 SLBR-H and Thr483 SLBR-B ).…”