Crystal structure of sulerythrin, a rubrerythrin-like protein from a strictly aerobic archaeon, Sulfolobus tokodaii strain 7, shows unexpected domain swapping.
Sulerythrin is the first rubrerythrin-like protein to be isolated from an aerobic organism, Sulfolobus tokodaii strain 7, and it lacks a C-terminal rubredoxin-like FeS(4) domain. The protein purified from Sulfolobus cells was crystallized, and the crystal structure was determined at 1.7 A resolution. The dimer of sulerythrin exhibited "domain-swapping" at the loop connecting alphaB and alphaC, hybrid four-helix bundles consisting of alphaA/B and alphaC/D being formed. The structure and atomic identity of the binuclear metal center were determined by means of anomalous scattering analysis. The site contained 1.0 mol of hexacoordinate Fe, 0.80-0.87 mol of tetracoordinate Zn, and 0.73-0.88 mol of putative O(2) per monomer. The metal ions were found at exchanged positions compared to those in the Fe/Zn-containing rubrerythrin from Desulfovibrio vulgaris. The results demonstrate that the binuclear metal center of rubrerythrin-like proteins is plastic in its ability to bind metal ions.
Fushinobu
Shinya
S
Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. asfushi@mail.ecc.u-tokyo.ac.jp
Shoun
Hirofumi
H
Wakagi
Takayoshi
T
D000332:Aerobiosis; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D003198:Computer Simulation; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D005288:Ferredoxins / Q000737:chemistry*; D006422:Hemerythrin; D007501:Iron / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012416:Rubredoxins; D017386:Sequence Homology, Amino Acid; D016944:Sulfolobus / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D005288:Ferredoxins; D006422:Hemerythrin; D012416:Rubredoxins; C055857:rubrerythrins; D007501:Iron; D015032:Zinc