gkd:K6Q96_23980 K11903 type VI secretion system secreted protein Hcp | (GenBank) Hcp family type VI secretion system effector gkd:K6Q96_19415 K11900 type VI secretion system protein ImpC | (GenBank) tssC; type VI secretion system contractile sheath large subunit gkd:K6Q96_19410 K11901 type VI secretion system protein ImpB | (GenBank) tssB; type VI secretion system contractile sheath small subunit