Pasteurella multocida toxin (PMT) inhibits osteoblastic differentiation in mammals and birds. Its N-terminal region binds to target cells, while its C-terminal region, with a Trojan horse-like shape, carries the intracellularly active moiety. The latter consists of three distinct domains: C1 (Pfam:PF11647), C2 and C3. This entry represents the larger of these domains, the central region C2, which has 18 helices and nine beta-strands and is organised into two subdomains with typical alpha-beta structures characteristic of nucleotide-binding proteins [1]. This domain is also found in the Ras/Rap1-specific endopeptidase (RRSP), an effector domain from the multifunctional-autoprocessing repeats-in- toxin (MARTX) toxin from Vibrio vulnificus responsible for the disruption of host innate immune defenses during infection [2,3].

1: Crystal structures reveal a thiol protease-like catalytic triad in the C-terminal region of Pasteurella multocida toxin. Kitadokoro K, Kamitani S, Miyazawa M, Hanajima-Ozawa M, Fukui A, Miyake M, Horiguchi Y; Proc Natl Acad Sci U S A. 2007;104:5139-5144. PMID:17360394

2: The bacterial Ras/Rap1 site-specific endopeptidase RRSP cleaves Ras through an atypical mechanism to disrupt Ras-ERK signaling. Biancucci M, Minasov G, Banerjee A, Herrera A, Woida PJ, Kieffer MB, Bindu L, Abreu-Blanco M, Anderson WF, Gaponenko V, Stephen AG, Holderfield M, Satchell KJF; Sci Signal. 2018; [Epub ahead of print] PMID:30279169

3: Structural basis of inactivation of Ras and Rap1 small GTPases by Ras/Rap1-specific endopeptidase from the sepsis-causing pathogen Vibrio vulnificus. Jang SY, Hwang J, Kim BS, Lee EY, Oh BH, Kim MH; J Biol Chem. 2018;293:18110-18122. PMID:30282804