Literature summary for 3.6.4.13 extracted from

De, I.; Bessonov, S.; Hofele, R.; dos Santos, K.; Will, C.L.; Urlaub, H.; Luehrmann, R.; Pena, V.
The RNA helicase Aquarius exhibits structural adaptations mediating its recruitment to spliceosomes (2015), Nat. Struct. Mol. Biol., 22, 138-144 .

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Activating Compound

Activating Compound	Comment	Organism	Structure
RNA	Aquarius hydrolyzes ATP, and this activity is highly stimulated in the presence of a 22-nt RNA with a random sequence. Aquarius does not bind a blunt-ended RNA duplex, and correspondingly the latter does not stimulate Aquarius's ATPase activity	Homo sapiens

Crystallization (Commentary)

Crystallization (Comment)	Organism
purified recombinant enzyme Aquanrius, X-ray diffraction structure determination and analysis at 2.3 A resolution	Homo sapiens

Protein Variants

Protein Variants	Comment	Organism
K829A	site-directed mutagenesis, mutation of the invariant lysine residue from motif I involved in ATP binding and hydrolysis drastically reduced Aquarius's ability to bind ATP and ADP and to hydroxadlyze ATP, the mutant shows significantly reduced ATPase activity compared to wild-type enzyme	Homo sapiens
Y1196A	site-directed mutagenesis, mutation of a conserved aromatic residue located near the putative RNA-binding surface of the RecA2 inhibits Aquarius's RNA-unwinding activity without changing its RNA-binding and ATPase properties, a helicase-deficient mutant	Homo sapiens

Inhibitors

Inhibitors	Comment	Organism	Structure
AMP-PNP	structure of Aquarius in complex with AMP-PNP, modelling, overview	Homo sapiens

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
nucleus	-	Homo sapiens	5634	-

Metals/Ions

Metals/Ions	Comment	Organism	Structure
Mg2+	required	Homo sapiens

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
ATP + H2O	Homo sapiens	-	ADP + phosphate	-	?
additional information	Homo sapiens	multiple cross-links between Aquarius and hSyf1, hIsy1, CCDC16 or CypE, with the majority of the cross-linked residues located in domains or structural insertions specific for Aquarius, such as the ARM, pointer and thumb domains, and in the large insertions of the beta-barrel	?	-	-

Organism

Organism	UniProt	Comment	Textmining
Homo sapiens	O60306	-	-

Source Tissue

Source Tissue	Comment	Organism	Textmining
HeLa cell	-	Homo sapiens	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
ATP + H2O	-	Homo sapiens	ADP + phosphate	-	?
additional information	multiple cross-links between Aquarius and hSyf1, hIsy1, CCDC16 or CypE, with the majority of the cross-linked residues located in domains or structural insertions specific for Aquarius, such as the ARM, pointer and thumb domains, and in the large insertions of the beta-barrel	Homo sapiens	?	-	-
additional information	Aquarius exhibits ATPase and RNA-unwinding activity in vitro. Consistently with its possessing a Q motif and thus specifically binding ATP, Aquarius does not hydrolyze GT. Aquarius does not bind a blunt-ended RNA duplex	Homo sapiens	?	-	-

Subunits

Subunits	Comment	Organism
More	enzyme Aquarius is integrated into the spliceosome as part of the intron-binding complex (IBC). The ARM domain is essential for IBC formation	Homo sapiens
pentamer	-	Homo sapiens

Synonyms

Synonyms	Comment	Organism
Aquarius	-	Homo sapiens
DExH/D-box RNA helicase	-	Homo sapiens
IBP160	-	Homo sapiens
intron-binding protein 160	-	Homo sapiens
RNA helicase Aquarius	-	Homo sapiens

General Information

General Information	Comment	Organism
malfunction	an ATPase-deficient Aquarius mutant hinders splicing	Homo sapiens
metabolism	the spliceosome's structural rearrangements are driven by eight conserved DExH/D-box RNA helicases that contain two RecA-like domains, which form a motor module required for ATP hydrolysis, RNA unwinding and coupling of these two processes. RNA helixadcases can have very diverse functions, including proofreading specific steps of pre-mRNA splicing. Most helicases also conxadtain specific accessory domains important for their regulation or task-specific function. The human spliceosome contains five addixadtional RNA helicases (Aquarius, SF3b125, elFAIII and DDX35 and Abstrakt). Multiple cross-links between Aquarius and hSyf1, hIsy1, CCDC16 or CypE, with the majority of the cross-linked residues located in domains or structural insertions specific for Aquarius, such as the ARM, pointer and thumb domains, and in the large insertions of the beta-barrel. The for intron-binding complex (IBC) is cross-linked to U2 SF3a and SF3b proteins, interaction partners of the IBC in the spliceosome. The Aquarius ARM domain is cross-linked to SF3b155	Homo sapiens
additional information	the SF1 core of Aquarius consists of two RecA-like domains, an alpha-helical stalk and a beta-barrel domain. The canonical sequence motifs of RNA helicases are conserved, and the ATP analogue binds with the adenine sandwiched between Leu1157 and Ile800. The amino group of the adenine is recognized by Gln806 from the Q motif, a distinctive feature of helicases able to use only ATP. The space between the RecA1, RecA2, beta-barrel and a domain that we denote as an armadillo (ARM) domain is filled by the so-called stalk, a structural unit encompassing 125 residues (416-492 and 660-710) exhibiting helixadces, extensive coils and loops. The large surfaces that the stalk shares with other domains suggest that it has a key architectural role. Notably, numerous large hydrophobic residues that mediate these contacts are highly conxadserved. Aquarius's ARM domain is required for intron-binding complex (IBC) formation	Homo sapiens
physiological function	RNA helicase Aquarius is crucial for the assembly of box C and box D (box C/D) small nucleolar RNPs (snoRNPs), whose small nucleolar RNAs (snoRNAs) are found in introns about 50 nt upstream of the BS, i.e., 10 nt upstream of Aquarius's binding site. The ATP hydrolysis by Aquarius is required for efficient pre-mRNA splicing	Homo sapiens

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Release 2023.1 (January 2023)