3IXV

Scorpion Hemocyanin resting state pseudo atomic model built based on cryo-EM density map

Summary for 3IXV

• Entry DOI: 10.2210/pdb3ixv/pdb
• Related: 3IXW
• EMDB information: 5100 5101
• Descriptor: Hemocyanin AA6 chain (1 entity in total)
• Functional Keywords: hemocyanin, hc, phenolxoidase activity, tyrosinase (ty), catecholoxidase (co), enzyme, sds, cryo-em, single particle analysis, copper, metal-binding, oxygen transport, phosphoprotein, secreted, transport, oxygen binding
• Biological source: Androctonus australis (Sahara scorpion)
• Total number of polymer chains: 12
• Total formula weight: 862604.34

Authors

Cong, Y.,Zhang, Q.,Woolford, D.,Schweikardt, T.,Khant, H.,Ludtke, S.,Chiu, W.,Decker, H. (deposition date: 2009-02-13, release date: 2009-06-02, Last modification date: 2024-02-21)

Primary citation

Cong, Y.,Zhang, Q.,Woolford, D.,Schweikardt, T.,Khant, H.,Dougherty, M.,Ludtke, S.J.,Chiu, W.,Decker, H.
Structural Mechanism of SDS-Induced Enzyme Activity of Scorpion Hemocyanin Revealed by Electron Cryomicroscopy.
Structure, 17:749-758, 2009

PubMed Abstract: Phenoloxidases (POs) occur in all organisms and are involved in skin and hair coloring in mammals, and initiating melanization in wound healing. Mutation or overexpression of PO can cause albinism or melanoma, respectively. SDS can convert inactive PO and the oxygen carrier hemocyanin (Hc) into enzymatically active PO. Here we present single-particle cryo-EM maps at subnanometer resolution and pseudoatomic models of the 24-oligomeric Hc from scorpion Pandinus imperator in resting and SDS-activated states. Our structural analyses led to a plausible mechanism of Hc enzyme PO activation: upon SDS activation, the intrinsically flexible Hc domain I twists away from domains II and III in each subunit, exposing the entrance to the active site; this movement is stabilized by enhanced interhexamer and interdodecamer interactions, particularly in the central linker subunits. This mechanism could be applicable to other type 3 copper proteins, as the active site is highly conserved.

PubMed: 19446530
DOI: 10.1016/j.str.2009.03.005

Experimental method

ELECTRON MICROSCOPY (6.8 Å)