PMID: 28291752

Authors:

Fukuda Y, Mizohata E, Inoue T

Title:

New molecular packing in a crystal of pseudoazurin from Alcaligenes faecalis: a double-helical arrangement of blue copper.

Journal:

Acta Crystallogr F Struct Biol Commun. 2017 Mar 1;73(Pt 3):159-166. doi:, 10.1107/S2053230X17002631. Epub 2017 Feb 28.

Abstract:

Pseudoazurin from the denitrifying bacterium Alcaligenes faecalis (AfPAz) is a blue copper protein and functions as an electron donor to copper-containing nitrite reductase (CuNIR). Conventionally, AfPAz has been crystallized using highly concentrated ammonium sulfate as a precipitant. Here, a needle-like crystal of AfPAz grown in a solution containing a macromolecular precipitant, polyethylene glycol 8000 (PEG 8000), is reported. The crystal belonged to space group P61, with unit-cell parameters a = b = 68.7, c = 94.2 A. The structure has been determined and refined at 2.6 A resolution. The asymmetric unit contained two AfPAz molecules contacting each other on negatively charged surfaces. The molecular packing of the crystal showed a right-handed double-helical arrangement of AfPAz molecules and hence of blue copper sites. This structure provides insight into the excluded-volume effect of PEG and the manner of assembly of AfPAz.