6A7H

Bacterial protein toxins

Summary for 6A7H

• Entry DOI: 10.2210/pdb6a7h/pdb
• Descriptor: RTX toxin, SULFATE ION (3 entities in total)
• Functional Keywords: protein toxins, virulence, toxin
• Biological source: Vibrio vulnificus CMCP6
• Total number of polymer chains: 4
• Total formula weight: 212778.90

Authors

Kim, M.H.,Hwang, J.,Jang, S.Y. (deposition date: 2018-07-03, release date: 2018-10-10, Last modification date: 2024-03-27)

Primary citation

Jang, S.Y.,Hwang, J.,Kim, B.S.,Lee, E.Y.,Oh, B.H.,Kim, M.H.
Structural basis of inactivation of Ras and Rap1 small GTPases by Ras/Rap1-specific endopeptidase from the sepsis-causing pathogenVibrio vulnificus
J. Biol. Chem., 293:18110-18122, 2018

PubMed Abstract: Multifunctional autoprocessing repeats-in-toxin (MARTX) toxins are secreted by Gram-negative bacteria and function as primary virulence-promoting macromolecules that deliver multiple cytopathic and cytotoxic effector domains into the host cytoplasm. Among these effectors, Ras/Rap1-specific endopeptidase (RRSP) catalyzes the sequence-specific cleavage of the Switch I region of the cellular substrates Ras and Rap1 that are crucial for host innate immune defenses during infection. To dissect the molecular basis underpinning RRSP-mediated substrate inactivation, we determined the crystal structure of an RRSP from the sepsis-causing bacterial pathogen (RRSP). Structural and biochemical analyses revealed that RRSP is a metal-independent TIKI family endopeptidase composed of an N-terminal membrane-localization and substrate-recruitment domain (N lobe) connected via an inter-lobe linker to the C-terminal active site-coordinating core β-sheet-containing domain (C lobe). Structure-based mutagenesis identified the 2His/2Glu catalytic residues in the core catalytic domain that are shared with other TIKI family enzymes and that are essential for Ras processing. KRas cleavage assays disclosed that deleting the N lobe in RRSP causes complete loss of enzymatic activity. Endogenous Ras cleavage assays combined with confocal microscopy analysis of HEK293T cells indicated that the N lobe functions both in membrane localization via the first α-helix and in substrate assimilation by altering the functional conformation of the C lobe to facilitate recruitment of cellular substrates. Collectively, these results indicate that RRSP is a critical virulence factor that robustly inactivates Ras and Rap1 and augments the pathogenicity of invading bacteria via the combined effects of its N and C lobes.

PubMed: 30282804
DOI: 10.1074/jbc.RA118.004857

Experimental method

X-RAY DIFFRACTION (2.301 Å)