The structure of a yeast RNA-editing deaminase provides insight into the fold and function of activation-induced deaminase and APOBEC-1.

ABSTRACT: 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 importantl

SUBMITTER: Xie K 

PROVIDER: S-EPMC419566 | biostudies-literature | 2004 May

REPOSITORIES: biostudies-literature