Crystal structure of Escherichia coli SufC, an ABC-type ATPase component of the SUF iron-sulfur cluster assembly machinery |
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Authors: | Kitaoka Shintaro Wada Kei Hasegawa Yuko Minami Yoshiko Fukuyama Keiichi Takahashi Yasuhiro |
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Affiliation: | Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. |
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Abstract: | SufC is an ATPase component of the SUF machinery, which is involved in the biosynthesis of Fe-S clusters. To gain insight into the function of this protein, we have determined the crystal structure of Escherichia coli SufC at 2.5A resolution. Despite the similarity of the overall structure with ABC-ATPases (nucleotide-binding domains of ABC transporters), some key differences were observed. Glu171, an invariant residue involved in ATP hydrolysis, is rotated away from the nucleotide-binding pocket to form a SufC-specific salt bridge with Lys152. Due to this salt bridge, D-loop that follows Glu171 is flipped out to the molecular surface, which may sterically inhibit the formation of an active dimer. Thus, the salt bridge may play a critical role in regulating ATPase activity and preventing wasteful ATP hydrolysis. Furthermore, SufC has a unique Q-loop structure on its surface, which may form a binding site for its partner proteins, SufB and/or SufD. |
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Keywords: | ABC-ATPase ABC transporter Crystal structure Iron-sulfur cluster SufC |
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