title: Requirement of dimerization for RNA editing activity of adenosine deaminases acting on RNA.
abstract: Adenosine deaminases acting on RNA (ADAR) convert adenosine residues into inosines in double-stranded RNA. Three vertebrate ADAR gene family members, ADAR1, ADAR2, and ADAR3, have been identified. The catalytic domain of all three ADAR gene family members is very similar to that of Escherichia coli cytidine deaminase and APOBEC-1. Homodimerization is essential for the enzyme activity of those cytidine deaminases. In this study, we investigated the formation of complexes between differentially epitope-tagged ADAR monomers by sequential affinity chromatography and size exclusion column chromatography. Both ADAR1 and ADAR2 form a stable enzymatically active homodimer complex, whereas ADAR3 remains as a monomeric, enzymatically inactive form. No heterodimer complex formation among different ADAR gene family members was detected. Analysis of HeLa and mouse brain nuclear extracts suggested that endogenous ADAR1 and ADAR2 both form a homodimer complex. Interestingly, endogenous ADAR3 also appears to form a homodimer complex, indicating the presence of a brain-specific mechanism for ADAR3 dimerization. Homodimer formation may be necessary for ADAR to act as active deaminases. Analysis of dimer complexes consisting of one wild-type and one mutant monomer suggests functional interactions between the two subunits during site-selective RNA editing.
authors.affiliation: Wistar Institute, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Dan-Sung C
authors.initials: DS
authors.lastname: Cho
authors.forename: Weidong
authors.initials: W
authors.lastname: Yang
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Lee
authors.forename: Ramin
authors.initials: R
authors.lastname: Shiekhattar
authors.forename: John M
authors.initials: JM
authors.lastname: Murray
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nishikura
mesh_terms: D000243:Adenosine Deaminase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D019281:Dimerization; D004926:Escherichia coli; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D012313:RNA / Q000235:genetics / Q000378:metabolism; D017393:RNA Editing; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D012313:RNA; D000243:Adenosine Deaminase