Crystal structure of atypical cytoplasmic ABC-ATPase SufC from Thermus thermophilus HB8

Satoshi Watanabe, Akiko Kita, Kunio Miki

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15 Citations (Scopus)


SufC, a cytoplasmic ABC-ATPase, is one of the most conserved Suf proteins. SufC forms a stable complex with SufB and SufD, and the SufBCD complex interacts with other Suf proteins in the Fe-S cluster assembly. We have determined the crystal structure of SufC from Thermus thermophilus HB8 in nucleotide-free and ADP-Mg-bound states at 1.7 Å and 1.9 Å resolution, respectively. The overall architecture of the SufC structure is similar to other ABC ATPases structures, but there are several specific motifs in SufC. Three residues following the end of the Walker B motif form a novel 310 helix which is not observed in other ABC ATPases. Due to the novel 310 helix, a conserved glutamate residue involved in ATP hydrolysis is flipped out. Although this unusual conformation is unfavorable for ATP hydrolysis, salt-bridges formed by conserved residues and a strong hydrogen-bonding network around the novel 310 helix suggest that the novel 310 helix of SufC is a rigid conserved motif. Compared to other ABC-ATPase structures, a significant displacement occurs at a linker region between the ABC α/β domain and the α-helical domain. The linker conformation is stabilized by a hydrophobic interaction between conserved residues around the Q loop. The molecular surfaces of SufC and the C-terminal helices of SufD (PDB code: 1VH4) suggest that the unusual linker conformation conserved among SufC proteins is probably suitable for interacting with SufB and SufD.

Original languageEnglish
Pages (from-to)1043-1054
Number of pages12
JournalJournal of Molecular Biology
Issue number5
Publication statusPublished - 2005 Nov 11


  • ABC-ATPase
  • Crystal structure
  • Hydrogen-bonding network
  • Hydrophobic interaction
  • Suf operon


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