Poster: Oxidative Stress

Abs # 126: The Arabidopsis ankyrin repeat-containing protein 2 interacts with the transmembrane domain of the peroxisomal antioxidant enzyme, ascorbate peroxidase 3

Presenter:	Yan, Juqiang , xiyan@ttu.edu
Authors	Yan, Juqiang  (A)   Zhang, Hong  (A)   Wang, Jing  (A)   Narendra, Savitha  (A)   Venkataramani, Sujatha  (A)   Li, Qingtian  (A)   Mano, Shoji  (B)   Nishimura, Mikio  (B)
Affiliations:	(A): Texas Tech University (B): National Institute for Basic Biology

The Arabidopsis ankyrin repeat-containing protein 2 (AKR2) was identified as a GF14l-interacting protein from yeast two-hybrid screening (GF14l is a 14-3-3 protein). The AKR2 interacts with another GF14l-interacting protein, the peroxisomal ascorbate peroxidase 3 (APX3) both in vivo and in vitro. The protein-protein interaction between AKR2 and APX3 appears to involve the N-terminal side of AKR2 (1 to 207) and the C-terminal transmembrane domain of APX3. Since the transmembrane domain of APX3 anchors APX3 on the peroxisomal membranes, the AKR2-APX3 interaction may prevent APX3 from binding to peroxisomal membranes, hinting a mechanism by which APX3¡¯s targeting to peroxisome or biogenesis is regulated. Preliminary data suggest that AKR2 is most likely located in cytoplasm, whereas APX3 is found in both cytoplasm and peroxisomes, supporting that AKR2 can interact with APX3 in cytoplasm. The AKR2 binding site on APX3 does not overlap with the GF14l binding site, suggesting that these proteins can form a protein complex in plant cells. Because AKR2 is structurally similar to animal regulatory protein IkB, it might be subject to quick degradation upon certain signal stimulations like what happens with IkB in animals, which expose the transmembrane of APX3 and allows it to be inserted into peroxisomal membrane, perhaps with the help of GF14l during the insertion process