RHAU explained

RHAU (RNA Helicase associated with AU-rich element, also known as DHX36 or G4R1) is a 114-kDa human RNA helicase of the DEAH-box family of helicases encoded by the DHX36 gene.^[1]

Structure

Structurally, RHAU is a 1008 amino acid-long modular protein. It consists of a ~440-amino acid helicase core comprising all signature motifs of the DEAH-box family of helicases with N- and C-terminal flanking regions of ~180 and ~380 amino acids, respectively. Like all the DEAH-box proteins, the helicase associated domain is located adjacent to the helicase core region and occupies 75% of the C-terminal region.

Function

RHAU exhibits a unique ATP-dependent guanine-quadruplex (G4) resolvase activity and specificity for its substrate in vitro.^{[2] [3]} RHAU binds G4-nucleic acid with sub-nanomolar affinity and unwinds G4 structures much more efficiently than double-stranded nucleic acid. Consistent with these biochemical observations, RHAU was also identified as the major source of tetramolecular RNA-resolving activity in HeLa cell lysates.

Previous work showed that RHAU associates with mRNAs and re-localises to stress granules (SGs) upon translational arrest induced by various environmental stresses.^{[4] [5]} A region of the first 105 amino acid was shown to be critical for RNA binding and re-localisation to SGs.^[4]

External links

• Group Yoshikuni Nagamine homepage
• Group Steven Akman homepage

Notes and References

1. 10.1016/S0888-7543(03)00049-1 . Abdelhaleem M, Maltais L, Wain H . The human DDX and DHX gene families of putative RNA helicases . Genomics . 81 . 6 . 618–22 . June 2003 . 12782131 .
2. Vaughn JP, Creacy SD, Routh ED, etal . The DEXH protein product of the DHX36 gene is the major source of tetramolecular quadruplex G4-DNA resolving activity in HeLa cell lysates . The Journal of Biological Chemistry . 280 . 46 . 38117–20 . November 2005 . 16150737 . 10.1074/jbc.C500348200. free .
3. Creacy SD, Routh ED, Iwamoto F, Nagamine Y, Akman SA, Vaughn JP . G4 resolvase 1 binds both DNA and RNA tetramolecular quadruplex with high affinity and is the major source of tetramolecular quadruplex G4-DNA and G4-RNA resolving activity in HeLa cell lysates . The Journal of Biological Chemistry . 283 . 50 . 34626–34 . December 2008 . 18842585 . 2596407 . 10.1074/jbc.M806277200. free .
4. Chalupníková K, Lattmann S, Selak N, Iwamoto F, Fujiki Y, Nagamine Y . Recruitment of the RNA helicase RHAU to stress granules via a unique RNA-binding domain . The Journal of Biological Chemistry . 283 . 50 . 35186–98 . December 2008 . 18854321 . 10.1074/jbc.M804857200 . free . 3259895.
5. Web site: Kateřina . Chalupníková . 2008 . Characterizing functional domains of the RNA helicase RHAU involved in subcellular localization and RNA interaction.