Part of the H1 type VI secretion system (H1-T6SS) specialized secretion system, which delivers several virulence factors in both prokaryotic and eukaryotic cells during infection (PubMed:21325275, PubMed:24794869). Allows the delivery of the Tse7 toxin to target cells where it exerts toxicity through its nuclease domain (PubMed:24794869, PubMed:30455305). Deletion neither impacts secretion of components of the H1-T6SS nor requires H1-T6SS components for its own secretion (PubMed:21325275). However, simultaneous deletion of all three vgrG genes (vgrG1a, vgrG1b and vgrG1c) totally abrogates bacterial killing (PubMed:24794869). Belongs to the VgrG protein family.