8K9P

Neutron X-ray joint structure of pseudoazurin from Alcaligenes faecalis

Summary for 8K9P

• Entry DOI: 10.2210/pdb8k9p/pdb
• Related: 8K9N
• Descriptor: Pseudoazurin, COPPER (II) ION, SULFATE ION, ... (4 entities in total)
• Functional Keywords: blue copper, electron transfer, electron transport
• Biological source: Alcaligenes faecalis
• Total number of polymer chains: 1
• Total formula weight: 13832.47

Authors

Fukuda, Y.,Kurihara, K.,Inoue, T.,Tamada, T. (deposition date: 2023-08-01, release date: 2024-02-14, Last modification date: 2024-02-21)

Primary citation

Fukuda, Y.,Lintuluoto, M.,Kurihara, K.,Hasegawa, K.,Inoue, T.,Tamada, T.
Overlooked Hydrogen Bond in a Blue Copper Protein Uncovered by Neutron and Sub- angstrom ngstrom Resolution X-ray Crystallography.
Biochemistry, 63:339-347, 2024

PubMed Abstract: Metalloproteins play fundamental roles in organisms and are utilized as starting points for the directed evolution of artificial enzymes. Knowing the strategies of metalloproteins, by which they exquisitely tune their activities, will not only lead to an understanding of biochemical phenomena but also contribute to various applications. The blue copper protein (BCP) has been a renowned model system to understand the biology, chemistry, and physics of metalloproteins. Pseudoazurin (Paz), a blue copper protein, mediates electron transfer in the bacterial anaerobic respiratory chain. Its redox potential is finely tuned by hydrogen (H) bond networks; however, difficulty in visualizing H atom positions in the protein hinders the detailed understanding of the protein's structure-function relationship. We here used neutron and sub-ångström resolution X-ray crystallography to directly observe H atoms in Paz. The 0.86-Å-resolution X-ray structure shows that the peptide bond between Pro80 and the His81 Cu ligand deviates from the ideal planar structure. The 1.9-Å-resolution neutron structure confirms a long-overlooked H bond formed by the amide of His81 and the S atom of another Cu ligand Cys78. Quantum mechanics/molecular mechanics calculations show that this H bond increases the redox potential of the Cu site and explains the experimental results well. Our study demonstrates the potential of neutron and sub-ångström resolution X-ray crystallography to understand the chemistry of metalloproteins at atomic and quantum levels.

PubMed: 38232298
DOI: 10.1021/acs.biochem.3c00517

Experimental method

NEUTRON DIFFRACTION (1.9 Å)
X-RAY DIFFRACTION (1.5 Å)