2nyt
From Proteopedia
The APOBEC2 Crystal Structure and Functional Implications for AID
Overview
APOBEC-2 (APO2) belongs to the family of apolipoprotein B messenger RNA-editing enzyme catalytic (APOBEC) polypeptides, which deaminates mRNA and single-stranded DNA. Different APOBEC members use the same deamination activity to achieve diverse human biological functions. Deamination by an APOBEC protein called activation-induced cytidine deaminase (AID) is critical for generating high-affinity antibodies, and deamination by APOBEC-3 proteins can inhibit retrotransposons and the replication of retroviruses such as human immunodeficiency virus and hepatitis B virus. Here we report the crystal structure of APO2. APO2 forms a rod-shaped tetramer that differs markedly from the square-shaped tetramer of the free nucleotide cytidine deaminase, with which APOBEC proteins share considerable sequence homology. In APO2, two long alpha-helices of a monomer structure prevent the formation of a square-shaped tetramer and facilitate formation of the rod-shaped tetramer via head-to-head interactions of two APO2 dimers. Extensive sequence homology among APOBEC family members allows us to test APO2 structure-based predictions using AID. We show that AID deamination activity is impaired by mutations predicted to interfere with oligomerization and substrate access. The structure suggests how mutations in patients with hyper-IgM-2 syndrome inactivate AID, resulting in defective antibody maturation.
About this Structure
2NYT is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
The APOBEC-2 crystal structure and functional implications for the deaminase AID., Prochnow C, Bransteitter R, Klein MG, Goodman MF, Chen XS, Nature. 2007 Jan 25;445(7126):447-51. Epub 2006 Dec 24. PMID:17187054 Page seeded by OCA on Sun May 4 10:05:27 2008
