Crystal Structure of the GTP-binding Protein Obg from Thermus thermophilus HB8

Mutsuko Kukimoto-Niino, Kazutaka Murayama, Mio Inoue, Takaho Terada, Jeremy R.H. Tame, Seiki Kuramitsu, Mikako Shirouzu, Shigeyuki Yokoyama

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


Obg comprises a unique family of high-molecular mass GTPases conserved from bacteria to eukaryotes. Bacterial Obg is essential for cellular growth, sporulation, and differentiation. Here, we report the crystal structure of the full-length form of Obg from Thermus thermophilus HB8 at 2.07Å resolution, in the nucleotide-free state. It reveals a three-domain arrangement, composed of the N-terminal domain, the guanine nucleotide-binding domain (G domain), and the C-terminal domain. The N-terminal and G domains have the Obg fold and the Ras-like fold, respectively. These global folds are similar to those of the recently published structure of the C-terminal domain-truncated form of Obg from Bacillus subtilis. On the other hand, the C-terminal domain of Obg was found to have a novel fold (the OCT fold). A comparison of the T.thermophilus and B.subtilis nucleotide-free Obg structures revealed significant conformational changes in the switch-I and switch-II regions of the G domain. Notably, the N-terminal domain is rotated drastically, by almost 180°, around the G domain axis. In the T.thermophilus Obg crystal, the nucleotide-binding site of the G domain interacts with the C-terminal domain of the adjacent molecule. These data suggest a possible domain rearrangement of Obg, and a potential role of the C-terminal domain in the regulation of the nucleotide-binding state.

Original languageEnglish
Pages (from-to)761-770
Number of pages10
JournalJournal of Molecular Biology
Issue number3
Publication statusPublished - 2004 Mar 26
Externally publishedYes


  • EF-Tu
  • GAP, GTPase-activating protein
  • GDI, guanine nucleotide dissociation inhibitor
  • GEF, guanine nucleotide exchange factor
  • GTP-binding protein
  • GTPase
  • MIR, multiple isomorphous replacement
  • MPD, 2-methyl-2,4-pentanediol
  • OCT, Obg C-terminal
  • Obg
  • Ras

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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