This is a GW domain found in the C-terminal of InlB proteins which belong to the extended family of internalin proteins found in Listeria [1]. These 80 residue GW domains are unique to InlB among the internalins but are present in other proteins of Gram-positive bacteria [2]. GW domains (named after a GlyTryp dipeptide) are structurally and evolutionary related to SH3 domains [1]. Despite of this, GW domains are unlikely to act as functional mimics of SH3 domains since their potential proline-binding sites are blocked or destroyed [2]. They are highly basic and interact with poly-anions. The GW domains are responsible for the non-covalent attachment to the bacterial cell surface through binding to lipoteichoic acid. The GW domains alone do not stimulate uptake, but they synergize with the Met-binding internalin domain [1].

1: Structural insights into Met receptor activation. Niemann HH; Eur J Cell Biol. 2011;90:972-981. PMID:21242015

2: GW domains of the Listeria monocytogenes invasion protein InlB are SH3-like and mediate binding to host ligands. Marino M, Banerjee M, Jonquieres R, Cossart P, Ghosh P; EMBO J. 2002;21:5623-5634. PMID:12411480