Structural and functional insights into sulfide:quinone oxidoreductase.
A sulfide:quinone oxidoreductase (SQR) was isolated from the membranes of the hyperthermoacidophilic archaeon Acidianus ambivalens, and its X-ray structure, the first reported for an SQR, was determined to 2.6 A resolution. This enzyme was functionally and structurally characterized and was shown to have two redox active sites: a covalently bound FAD and an adjacent pair of cysteine residues. Most interestingly, the X-ray structure revealed the presence of a chain of three sulfur atoms bridging those two cysteine residues. The possible implications of this observation in the catalytic mechanism for sulfide oxidation are discussed, and the role of SQR in the sulfur dependent bioenergetics of A. ambivalens, linked to oxygen reduction, is addressed.
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal.
José A
JA
Brito
Filipa L
FL
Sousa
Meike
M
Stelter
Tiago M
TM
Bandeiras
Clemens
C
Vonrhein
Miguel
M
Teixeira
Manuela M
MM
Pereira
Margarida
M
Archer
D041541:Acidianus / Q000201:enzymology / Q000378:metabolism; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011808:Quinone Reductases / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism
D019843:Archaeal Proteins; D008565:Membrane Proteins; D013440:Sulfides; D011808:Quinone Reductases; C073412:sulfide quinone reductase; D003545:Cysteine