biostudies-literatureUnknown99(18)Slaymaker DHIn plants, salicylic acid (SA) plays an important role in signaling both local and systemic defense responses. Previous efforts to identify SA effector proteins in tobacco have led to the isolation of two soluble cytoplasmic SA-binding proteins (SABPs): catalase, SABP, and an approximately 25-kDa protein, SABP2. Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts. SABP3 bound SA with an apparent dissociation constant (K(d)) of 3.7 microM and exhibited much greater affinity for biologically active than inactive analogs. Purification and partial sequencing of SABP3 indicated that it is the chloroplast carbonic anhydrase (CA). Confirming this finding, recombinant tobacco chloroplast CA exhibited both CA enzymatic and SA-binding activitiesProceedings of the National Academy of Sciences of the United States of America11640-5https://www.ebi.ac.uk/biostudies/studies/S-EPMC129322biostudies-literatureThe 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.PMC129322Navarre DASlaymaker DHdel Pozo OMartin GBKlessig DFClark DfalseThe 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.In plants, salicylic acid (SA) plays an important role in signaling both local and systemic defense responses. Previous efforts to identify SA effector proteins in tobacco have led to the isolation of two soluble cytoplasmic SA-binding proteins (SABPs): catalase, SABP, and an approximately 25-kDa protein, SABP2. Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts. SABP3 bound SA with an apparent dissociation constant (K(d)) of 3.7 microM and exhibited much greater affinity for biologically active than inactive analogs. Purification and partial sequencing of SABP3 indicated that it is the chloroplast carbonic anhydrase (CA). Confirming this finding, recombinant tobacco chloroplast CA exhibited both CA enzymatic and SA-binding activities2002-01-01T00:00:00Z2002 Sep2025-04-05T16:16:36.451Z2019-03-27T00:17:19ZS-EPMC1293221218525310.1073/pnas.182427699