Activation-induced deaminase (AID) uses base deamination for class-switch recombination and somatic hypermutation and is related to the mammalian RNA-editing enzyme apolipoprotein B editing catalytic subunit 1 (APOBEC-1). CDD1 is a yeast ortholog of APOBEC-1 that exhibits cytidine deaminase and RNA-editing activity ...
Activation-induced deaminase (AID) uses base deamination for class-switch recombination and somatic hypermutation and is related to the mammalian RNA-editing enzyme apolipoprotein B editing catalytic subunit 1 (APOBEC-1). CDD1 is a yeast ortholog of APOBEC-1 that exhibits cytidine deaminase and RNA-editing activity. Here, we present the crystal structure of CDD1 at 2.0-A resolution and its use in comparative modeling of APOBEC-1 and AID. The models explain dimerization and the need for trans-acting loops that contribute to active site formation. Substrate selectivity appears to be regulated by a central active site "flap" whose size and flexibility accommodate large substrates in contrast to deaminases of pyrimidine metabolism that bind only small nucleosides or free bases. Most importantly, the results suggested both AID and APOBEC-1 are equally likely to bind single-stranded DNA or RNA, which has implications for the identification of natural AID targets.
Related Citations:
Activation induced deaminase: the importance of being specific Smith, H.C., Bottaro, A., Sowden, M.P., Wedekind, J.E. (2004) Trends Genet 20: 224
Messenger RNA editing in mammals: new members of the APOBEC family seeking roles in the family business Wedekind, J.E., Dance, G.S., Sowden, M.P., Smith, H.C. (2003) Trends Genet 19: 207
Identification of the Yeast Cytidine Deaminase CDD1 as an Orphan C-to-U RNA Editase Dance, G.S., Beemiller, P., Yang, Y., Mater, D.V., Mian, I.S., Smith, H.C. (2001) Nucleic Acids Res 29: 1772
APOBEC-1 Dependent Cytidine to Uridine Editing of Apolipoprotein B RNA in Yeast Dance, G.S., Sowden, M.P., Yang, Y., Smith, H.C. (2000) Nucleic Acids Res 28: 424
Organizational Affiliation:
Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
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