InterPro domain: IPR034348

This entry represents an N-terminal domain of the ABC ATPase, RNase L inhibitor (RLI). RLI is also known as ABCE1, which contains two nucleotide-binding domains (NBDs) typical of the ABC transporter protein superfamily [ 1 ]; however, it lacks the transmembrane domains required for membrane transport functions [ 2 , 2 ].

RLI is a key enzyme in ribosomal biogenesis, formation of translation pre-initiation complexes, and assembly of HIV capsids [ 3 , 4 ]. RLI1 was first identified as an endoribonuclease inhibitor that interacts directly with RNase L to prevent it from binding 2-5A (5'-phosphorylated 2',5'-linked oligo- adenylates) [ 5 ]. Structurally, RLIs have an N-terminal Fe-S domain and two nucleotide binding domains which are arranged to form two composite active sites in their interface cleft [ 5 ]. RLI is one of the most conserved enzymes between archaea and eukaryotes with a sequence identity more than 48%. The high degree of evolutionary conservation suggests that RLI performs a central role in archaeal and eukaryotic physiology.

1. Cloning and characterization of a RNAse L inhibitor. A new component of the interferon-regulated 2-5A pathway. J. Biol. Chem. 270, 13308-17
2. The human ATP-binding cassette (ABC) transporter superfamily. Genome Res. 11, 1156-66
3. X-ray structure of RLI, an essential twin cassette ABC ATPase involved in ribosome biogenesis and HIV capsid assembly. Structure 13, 649-59
4. Identification of a host protein essential for assembly of immature HIV-1 capsids. Nature 415, 88-92