pkk:QQ992_15730 K11903 type VI secretion system secreted protein Hcp | (GenBank) Hcp family type VI secretion system effector pkk:QQ992_15690 K11900 type VI secretion system protein ImpC | (GenBank) tssC; type VI secretion system contractile sheath large subunit pkk:QQ992_15685 K11901 type VI secretion system protein ImpB | (GenBank) tssB; type VI secretion system contractile sheath small subunit