pza:HU749_019820 K11903 type VI secretion system secreted protein Hcp | (GenBank) Hcp family type VI secretion system effector pza:HU749_000465 K11900 type VI secretion system protein ImpC | (GenBank) tssC; type VI secretion system contractile sheath large subunit pza:HU749_000470 K11901 type VI secretion system protein ImpB | (GenBank) tssB; type VI secretion system contractile sheath small subunit