The tobacco salicylic acid-binding protein 3 (SABP3) is the chloroplast carbonic anhydrase, which exhibits antioxidant activity and plays a role in the hypersensitive defense response

摘要: In plants, salicylic acid (SA) plays an important role in signaling both local and systemic defense responses. Previous efforts to identify SA effector proteins tobacco have led the isolation of two soluble cytoplasmic SA-binding (SABPs): catalase, SABP, ≈25-kDa protein, SABP2. Here we describe identification SABP3, stroma chloroplasts. SABP3 bound with apparent dissociation constant (Kd) 3.7 μM exhibited much greater affinity for biologically active than inactive analogs. Purification partial sequencing indicated that it is chloroplast carbonic anhydrase (CA). Confirming this finding, recombinant CA enzymatic activities. Expression protein yeast also demonstrated CA/SABP3 has antioxidant activity. A second gene encoding was cloned, its encoded shown behave similarly purified as SABP3. Finally, silencing expression leaves suppressed Pto:avrPto-mediated hypersensitive response disease resistance. These results demonstrate may act through multiple plants shed further light on function