Type VI secretion system effector, Hcp
HCP is a family of proteins which are expressed in up to 1000 copies in Gram-negative bacteria. Together these copies aggregate into a needle-like shaft or tube that will penetrate other bacteria via a puncturing protein attached to its head. Initially Hcp forms a hexameric structure with a central channel of 40 Angstroms. These hexamers pile up one on top of each other forming nanotubes resembling the gp19 tail phage tube.
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