On the other half of 89K, four gene products display aa similarities to the Agrobacterium T4SS components. 05SSU0968 is a VirB1-type lytic transglycosylase (18% identity to the T4SS VirB1 component, accession number NP_059799.1), 05SSU0969 is a putative VirB4-like ATPase (41% identity to the T4SS VirB4 component, accession number NP_059802.1), 05SSU0971 is a hypothetical VirB6-like channel subunit (12% identity to the T4SS VirB6 component, accession number NP_ 059804.1), and 05SSU0973 is a putative VirD4-like coupling protein (40% identity to the T4SS VirD4 component, accession number NP_059816.1). Thus, 05SSU0968, 05SSU0969, 05SSU0971 and 05SSU0973 were accordingly designated virB1-89K, virB4-89K, virB6-89K and virD4-89K respectively. Based on these predictions, it was logical to assume that horizontal transfer of the 89K PAI may occur through a GI-type T4SS-mediated conjugation process.