Exosome RNA helicase Mtr4 is a essential RNA helicase, and is an exosome-activating cofactor. It functions together with the nuclear exosome being involved in processing of structured RNAs, including snRNAs and snoRNAs. It also plays a role in nuclear RNA surveillance pathways involving the so-called TRAMP complex [1,2,3]. It contains an arch domain, required for proper 5.8S rRNA processing, and appears to function independently of canonical helicase activity [3]. The arch domain comprises an helical stalk/elbow that flanks a KOW module which adopts a beta-barrel fold. Thsi entry represents the beta-barrel of MTR4 and related Ski2-like helicases. Ski2 from yeast has an overall similar structure to MTR4 proteins. However, it does not have the KOW motif [4] and it is not included in this entry.

1: The crystal structure of Mtr4 reveals a novel arch domain required for rRNA processing. Jackson RN, Klauer AA, Hintze BJ, Robinson H, van Hoof A, Johnson SJ; EMBO J. 2010;29:2205-2216. PMID:20512111

2: Structural analysis reveals the characteristic features of Mtr4, a DExH helicase involved in nuclear RNA processing and surveillance. Weir JR, Bonneau F, Hentschel J, Conti E; Proc Natl Acad Sci U S A. 2010;107:12139-12144. PMID:20566885

3: Structure of the frequency-interacting RNA helicase: a protein interaction hub for the circadian clock. Conrad KS, Hurley JM, Widom J, Ringelberg CS, Loros JJ, Dunlap JC, Crane BR; EMBO J. 2016;35:1707-1719. PMID:27340124

4: The crystal structure of S. cerevisiae Ski2, a DExH helicase associated with the cytoplasmic functions of the exosome. Halbach F, Rode M, Conti E; RNA. 2012;18:124-134. PMID:22114319