Solution structure of the GUCT domain from human RNA helicase II/Guβ reveals the RRM fold, but implausible RNA interactions

Satoshi Ohnishi, Kimmo Pääkkönen, Seizo Koshiba, Naoya Tochio, Manami Sato, Naohiro Kobayashi, Takushi Harada, Satoru Watanabe, Yutaka Muto, Peter Güntert, Akiko Tanaka, Takanori Kigawa, Shigeyuki Yokoyama

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Human RNA helicase II/Guaα (RH-II/Guaα) and RNA helicase II/Guf (RH-II/Guβ) are paralogues that share the same domain structure, consisting of the DEAD box helicase domain (DEAD), the helicase conserved C-terminal domain (helicase-C), and the GUCT domain. The N-terminal regions of the RH-II/Gu proteins, including the DEAD domain and the helicase-C domain, unwind double-stranded RNAs. The C-terminal tail of RH-II/Guaα, which follows the GUCT domain, folds a single RNA strand, while that of RH-II/Guβ does not, and the GUCT domain is not essential for either the RNA helicase or foldase activity. Thus, little is known about the GUCT domain. In this study, we have determined the solution structure of the RH-II/Guβ GUCT domain. Structural calculations using NOE-based distance restraints and residual dipolar coupling-based angular restraints yielded a well-defined structure with β-α-aα-β-β-α-β topology in the region for K585-A659, while the Pfam HMM algorithm defined the GUCT domain as G571-E666. This structure-based domain boundary revealed false positives in the sequence homologue search using the HMM definition. A structural homology search revealed that the GUCT domain has the RRM fold, which is typically found in RNA-interacting proteins. However, it lacks the surface- exposed aromatic residues and basic residues on the β-sheet that are important for the RNA recognition in the canonical RRM domains. In addition, the overall surface of the GUCT domain is fairly acidic, and thus the GUCT domain is unlikely to interact with RNA molecules. Instead, it may interact with proteins via its hydrophobic surface around the surface-exposed tryptophan.

Original languageEnglish
Pages (from-to)133-144
Number of pages12
JournalProteins: Structure, Function and Bioinformatics
Issue number1
Publication statusPublished - 2009 Jan 1
Externally publishedYes


  • GUCT domain
  • NMR
  • RNA helicase
  • RRM domain superfamily
  • Residual dipolar couplings
  • Structural genomics

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Molecular Biology


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