6PIH
Hexameric ArnA cryo-EM structure
Summary for 6PIH
| Entry DOI | 10.2210/pdb6pih/pdb |
| EMDB information | 0456 |
| Descriptor | Bifunctional polymyxin resistance protein ArnA, UDP-4-amino-4-deoxy-L-arabinose formyltransferase (2 entities in total) |
| Functional Keywords | polymyxin resistance, hexamer, tetramer, antibiotic |
| Biological source | Escherichia coli DH5[alpha] More |
| Total number of polymer chains | 12 |
| Total formula weight | 436650.01 |
| Authors | Yang, M.,Gehring, K. (deposition date: 2019-06-26, release date: 2019-07-31, Last modification date: 2024-03-13) |
| Primary citation | Yang, M.,Chen, Y.S.,Ichikawa, M.,Calles-Garcia, D.,Basu, K.,Fakih, R.,Bui, K.H.,Gehring, K. Cryo-electron microscopy structures of ArnA, a key enzyme for polymyxin resistance, revealed unexpected oligomerizations and domain movements. J.Struct.Biol., 208:43-50, 2019 Cited by PubMed Abstract: Gram-negative bacteria evade the attack of cationic antimicrobial peptides through modifying their lipid A structure in their outer membranes with 4-amino-4-deoxy-L-arabinose (Ara4N). ArnA is a crucial enzyme in the lipid A modification pathway and its deletion abolishes the polymyxin resistance of gram-negative bacteria. Previous studies by X-ray crystallography have shown that full-length ArnA forms a three-bladed propeller-shaped hexamer. Here, the structures of ArnA determined by cryo-electron microscopy (cryo-EM) reveal that ArnA exists in two 3D architectures, hexamer and tetramer. This is the first observation of a tetrameric ArnA. The hexameric cryo-EM structure is similar to previous crystal structures but shows differences in domain movements and conformational changes. We propose that ArnA oligomeric states are in a dynamic equilibrium, where the hexamer state is energetically more favorable, and its domain movements are important for cooperating with downstream enzymes in the lipid A-Ara4N modification pathway. The results provide us with new possibilities to explore inhibitors targeting ArnA. PubMed: 31344437DOI: 10.1016/j.jsb.2019.07.009 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (6.6 Å) |
Structure validation
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