| Primary Identifier | IPR018003 | Type | Family |
| Short Name | Insecticidal_toxin/plasmid_vir |
| description | This entry included insecticidal toxin complex proteins (TcaA, TccA, TcbA, TcdA) from Photorhabdus luminescens subsp. laumondii and Xenorhabdus nematophilus (Achromobacter nematophilus) [], and virulence proteins from Salmonella typhimurium that are encoded on a 90kb plasmid.P. luminescens and X. nematophilus are Gram-negative bacteria that form entomopathogenic symbioses with soil nematodes. The bacteria are found in the gut of entomopathogenic nematodes that invade and kill insects. When the nematode invades an insect host the bacteria are released into the insect haemocoel (the open circulatory system), both the bacteria and the nematode undergo multiple rounds of replication which kills the insect host. Mapping of the insecticidal toxin loci and studies on knockout mutants in P. luminescens showed that deletion of either tca or tcd loci dramatically reduced toxicity, while the double mutant tca/tcd abolished toxicity []. However the biology of toxin action is unclear as is the species range of insects the toxins are active against.S. typhimurium contains a 90kb plasmid that is associated withvirulence. This plasmid encodes at least 6 genes needed by thebacterium for invading host macrophages during infection. These includethe 70kDa mkaA protein [], a recognised virulence factor, and more recently described, four spv genes under the control of a regulator [].Deletion studies on the virulence plasmid have shown that an open reading frame encoding a 28kDa protein was needed for successful invasion of the host. This protein, designated mkfA [], VRP4 []or VirA []by differentgroups, is utilised by the microbe upon entry into macrophages, although the exact mechanism is unclear. |
