The type II secretion system (T2SS) is a multiprotein machinery penetrating the double membrane of Gram-negative bacteria, enabling the secretion of exoproteins and virulence factors. My project is focused on providing structural, kinetic and thermodynamic view of XcpR, motor ATPase of T2SS with its proteinaceous and nucleotide partners. These data are crucial for understanding mechanism of secretion employing T2SS.