4AZU

CRYSTAL STRUCTURE ANALYSIS OF OXIDIZED PSEUDOMONAS AERUGINOSA AZURIN AT PH 5.5 AND PH 9.0. A PH-INDUCED CONFORMATIONAL TRANSITION INVOLVES A PEPTIDE BOND FLIP

Summary for 4AZU

• Entry DOI: 10.2210/pdb4azu/pdb
• Descriptor: AZURIN, COPPER (II) ION, NITRATE ION, ... (4 entities in total)
• Functional Keywords: electron transport(copper binding)
• Biological source: Pseudomonas aeruginosa
• Cellular location: Periplasm: P00282
• Total number of polymer chains: 4
• Total formula weight: 56163.39

Authors

Nar, H.,Messerschmidt, A.,Huber, R. (deposition date: 1993-06-23, release date: 1994-01-31, Last modification date: 2024-06-05)

Primary citation

Nar, H.,Messerschmidt, A.,Huber, R.,van de Kamp, M.,Canters, G.W.
Crystal structure analysis of oxidized Pseudomonas aeruginosa azurin at pH 5.5 and pH 9.0. A pH-induced conformational transition involves a peptide bond flip.
J.Mol.Biol., 221:765-772, 1991

PubMed Abstract: The X-ray crystal structure of recombinant wild-type azurin from Pseudomonas aeruginosa was determined by difference Fourier techniques using phases derived from the structure of the mutant His35Leu. Two data sets were collected from a single crystal of oxidized azurin soaked in mother liquor buffered at pH 5.5 and pH 9.0, respectively. Both data sets extend to 1.93 A resolution. The two pH forms were refined independently to crystallographic R-factors of 17.6% (pH 5.5) and 17.5% (pH 9.0). The conformational transition previously attributed to the protonation/deprotonation of residue His35 (pKa(red) = 7.3, pKa(ox) = 6.2), which lies in a crevice of the protein close to the copper binding site, involves a concomitant Pro36-Gly37 main-chain peptide bond flip. At the lower pH, the protonated imidazole N delta 1 of His35 forms a strong hydrogen bond with the carbonyl oxygen from Pro36, while at alkaline pH the deprotonated N delta 1 acts as an acceptor of a weak hydrogen bond from HN Gly37. The structure of the remainder of the azurin molecule, including the copper binding site, is not significantly affected by this transition.

PubMed: 1942029
DOI: 10.1016/0022-2836(91)80173-R

Experimental method

X-RAY DIFFRACTION (1.9 Å)