3MHZ

1.7A structure of 2-fluorohistidine labeled Protective Antigen

Summary for 3MHZ

• Entry DOI: 10.2210/pdb3mhz/pdb
• Descriptor: Protective antigen, CALCIUM ION, TETRAETHYLENE GLYCOL, ... (4 entities in total)
• Functional Keywords: anthrax, toxin, 2-fluorohistidine, pore, histidine, receptor, hydrogen bonding
• Biological source: Bacillus anthracis (anthrax,anthrax bacterium)
• Cellular location: Secreted, extracellular space: P13423
• Total number of polymer chains: 1
• Total formula weight: 83223.12

Authors

Lovell, S.,Battaile, K.P.,Wimalasena, D.S.,Janowiak, B.E.,Miyagi, M.,Sun, J.,Hajduch, J.,Pooput, C.,Kirk, K.L.,Bann, J.G. (deposition date: 2010-04-09, release date: 2010-08-11, Last modification date: 2024-11-27)

Primary citation

Wimalasena, D.S.,Janowiak, B.E.,Lovell, S.,Miyagi, M.,Sun, J.,Zhou, H.,Hajduch, J.,Pooput, C.,Kirk, K.L.,Battaile, K.P.,Bann, J.G.
Evidence that histidine protonation of receptor-bound anthrax protective antigen is a trigger for pore formation.
Biochemistry, 49:6973-6983, 2010

PubMed Abstract: The protective antigen (PA) component of the anthrax toxin forms pores within the low pH environment of host endosomes through mechanisms that are poorly understood. It has been proposed that pore formation is dependent on histidine protonation. In previous work, we biosynthetically incorporated 2-fluorohistidine (2-FHis), an isosteric analogue of histidine with a significantly reduced pK(a) ( approximately 1), into PA and showed that the pH-dependent conversion from the soluble prepore to a pore was unchanged. However, we also observed that 2-FHisPA was nonfunctional in the ability to mediate cytotoxicity of CHO-K1 cells by LF(N)-DTA and was defective in translocation through planar lipid bilayers. Here, we show that the defect in cytotoxicity is due to both a defect in translocation and, when bound to the host cellular receptor, an inability to undergo low pH-induced pore formation. Combining X-ray crystallography with hydrogen-deuterium (H-D) exchange mass spectrometry, our studies lead to a model in which hydrogen bonds to the histidine ring are strengthened by receptor binding. The combination of both fluorination and receptor binding is sufficient to block low pH-induced pore formation.

PubMed: 20672855
DOI: 10.1021/bi100647z

Experimental method

X-RAY DIFFRACTION (1.7 Å)