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Crystal structure of Escherichia coli SufA involved in biosynthesis of iron–sulfur clusters: Implications for a functional dimer
Author(s) -
Wada Kei,
Hasegawa Yuko,
Gong Zhao,
Minami Yoshiko,
Fukuyama Keiichi,
Takahashi Yasuhiro
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.10.046
Subject(s) - dimer , protein subunit , cysteine , chemistry , crystallography , crystal structure , molecule , cluster (spacecraft) , protein structure , iron–sulfur cluster , stereochemistry , biochemistry , gene , enzyme , organic chemistry , computer science , programming language
IscA and SufA are paralogous proteins that play crucial roles in the biosynthesis of Fe–S clusters, perhaps through a mechanism involving transient Fe–S cluster formation. We have determined the crystal structure of E. coli SufA at 2.7 Å resolution. SufA exists as a homodimer, in contrast to the tetrameric organization of IscA. Furthermore, a C‐terminal segment containing two essential cysteine residues (Cys‐Gly‐Cys), which is disordered in the IscA structure, is clearly visible in one molecule (the α 1 subunit) of the SufA homodimer. Although this segment is disordered in the other molecule (the α 2 subunit), computer modeling of this segment based on the well‐defined conformation of α 1 subunit suggests that the four cysteine residues (Cys114 and Cys116 in each subunit) in the Cys‐Gly‐Cys motif are positioned in close proximity at the dimer interface. The arrangement of these cysteines together with the nearby Glu118 in SufA dimer may allow coordination of an Fe–S cluster and/or an Fe atom.