4bwg

Structural highlights

Function

[SUBA_ECOLX] Protease subunit of subtilase cytotoxin SubAB5 (PubMed:17024087). An endoprotease specific for host endoplasmic reticulum (ER) chaperone BiP/HSPA5, has no activity on human HSP70 or HSPA8 (PubMed:17024087). Cleaves between 'Leu-416' and 'Leu-417' of BiP/HSPA5 in the hinge between BiP's ATPase and protein-binding domains (PubMed:17024087). This induces host ER stress response and eventual cell death (PubMed:18005237, PubMed:18433465). Culture supernatant of E.coli expressing both subA and subB are toxic for Vero cells (African green monkey kidney cell line), Chinese hamster ovary cells and Hct-8 cells (human colonic epithelial cell line); the subunits are not toxic individually (PubMed:15226357). Purified SubAB5 is highly toxic, <0.1 pg is able to kill at least 50% of 30'000 Vero cells in a microtiter plate assay after 3 days; no cytotoxicity is seen at 24 hours (PubMed:15226357). Preabsorption with cells expressing a ganglioside GM2 mimic reduced cytotoxicity of SubAB5 by 93% in the Vero cytotoxicity assay (PubMed:15226357). Intraperitoneal injection of 200 ng of purified SubAB5 kills mice; the higher the dose the faster the mice die. Animals injected intraperitoneally with purified SubAB5 have microvascular thrombi in the brain and other organs, including the renal tubules and glomeruli (PubMed:15226357). Injection induces an unfolded response in mice (PubMed:17024087). Mice fed E.coli cells expressing cloned SubAB5 experience drastic weight loss and appear ill and lethargic (PubMed:15226357). Protein synthesis in Vero cells is transiently inhibited by SubAB5; both subunits are required for this effect (PubMed:17101670, PubMed:18005237, PubMed:18433465). Inhibition of protein synthesis is prevented by brefeldin A; cells are arrested in the G1 phase (PubMed:18005237). SubAB5 at 100 ng/ml induced caspase-dependent apoptosis in Vero cells through mitochondrial membrane damage (PubMed:19380466).^{[1] [2] [3] [4] [5] [6]}

References

1. ↑ Paton AW, Srimanote P, Talbot UM, Wang H, Paton JC. A new family of potent AB(5) cytotoxins produced by Shiga toxigenic Escherichia coli. J Exp Med. 2004 Jul 5;200(1):35-46. doi: 10.1084/jem.20040392. Epub 2004 Jun 28. PMID:15226357 doi:http://dx.doi.org/10.1084/jem.20040392
2. ↑ Paton AW, Beddoe T, Thorpe CM, Whisstock JC, Wilce MC, Rossjohn J, Talbot UM, Paton JC. AB5 subtilase cytotoxin inactivates the endoplasmic reticulum chaperone BiP. Nature. 2006 Oct 5;443(7111):548-52. PMID:17024087 doi:10.1038/nature05124
3. ↑ Morinaga N, Yahiro K, Matsuura G, Watanabe M, Nomura F, Moss J, Noda M. Two distinct cytotoxic activities of subtilase cytotoxin produced by shiga-toxigenic Escherichia coli. Infect Immun. 2007 Jan;75(1):488-96. doi: 10.1128/IAI.01336-06. Epub 2006 Nov 13. PMID:17101670 doi:http://dx.doi.org/10.1128/IAI.01336-06
4. ↑ Morinaga N, Yahiro K, Matsuura G, Moss J, Noda M. Subtilase cytotoxin, produced by Shiga-toxigenic Escherichia coli, transiently inhibits protein synthesis of Vero cells via degradation of BiP and induces cell cycle arrest at G1 by downregulation of cyclin D1. Cell Microbiol. 2008 Apr;10(4):921-9. doi: 10.1111/j.1462-5822.2007.01094.x. Epub, 2007 Nov 14. PMID:18005237 doi:http://dx.doi.org/10.1111/j.1462-5822.2007.01094.x
5. ↑ Wolfson JJ, May KL, Thorpe CM, Jandhyala DM, Paton JC, Paton AW. Subtilase cytotoxin activates PERK, IRE1 and ATF6 endoplasmic reticulum stress-signalling pathways. Cell Microbiol. 2008 Sep;10(9):1775-86. doi: 10.1111/j.1462-5822.2008.01164.x., Epub 2008 Apr 21. PMID:18433465 doi:http://dx.doi.org/10.1111/j.1462-5822.2008.01164.x
6. ↑ Matsuura G, Morinaga N, Yahiro K, Komine R, Moss J, Yoshida H, Noda M. Novel subtilase cytotoxin produced by Shiga-toxigenic Escherichia coli induces apoptosis in vero cells via mitochondrial membrane damage. Infect Immun. 2009 Jul;77(7):2919-24. doi: 10.1128/IAI.01510-08. Epub 2009 Apr, 20. PMID:19380466 doi:http://dx.doi.org/10.1128/IAI.01510-08