The effect of the side chain length of Asp and Glu on coordination structure of Cu(2+) in a de novo designed protein.
Metal ions in proteins are important not only for the formation of the proper structures but also for various biological activities. For biological functions such as hydrolysis and oxidation, metal ions often adopt unusual coordination structures. We constructed a stable scaffold for metal binding to create distorted metal coordination structures. A stable four stranded alpha-helical coiled-coil structure was used as the scaffold, and the metal binding site was in the cavity created at the center of the structure. Two His residues and one Asp or Glu residue were used to coordinate the metal ions, AM2D and AM2E, respectively. Cu(2+) bound to AM2D with an equatorial planar coordination structure with two His, one Asp, and H(2)O as detected by electron spin resonance and UV spectral analyzes. On the other hand, Cu(2+) had a slightly distorted square planar structure when it bound two His and Glu in AM2E, due to the longer side-chain of the Glu residue as compared to the Asp residue. Computational analysis also supported the distorted coordination structure of Cu(2+) in AM2E. This construct should be useful to create various coordinations of metal ions for catalytic functions.
Shiga
Daigo
D
Department of Material Sciences, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-chou, Nagoya 466-8555, Japan.
Nakane
Daisuke
D
Inomata
Tomohiko
T
Masuda
Hideki
H
Oda
Masayuki
M
Noda
Masanori
M
Uchiyama
Susumu
S
Fukui
Kiichi
K
Takano
Yu
Y
Nakamura
Haruki
H
Mizuno
Toshihisa
T
Tanaka
Toshiki
T
D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry*; D001665:Binding Sites; D002614:Chelating Agents / Q000138:chemical synthesis / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D018698:Glutamic Acid / Q000737:chemistry*; D008667:Metalloproteins / Q000737:chemistry*; D008958:Models, Molecular; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification
D002614:Chelating Agents; D008667:Metalloproteins; D011993:Recombinant Fusion Proteins; D001224:Aspartic Acid; D018698:Glutamic Acid; D003300:Copper