Abstract
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 activities. Expression of this protein in yeast also demonstrated that CA/SABP3 has antioxidant activity. A second gene encoding CA was also cloned, and its encoded protein was shown to behave similarly to that purified as SABP3. Finally, silencing of CA gene expression in leaves suppressed the Pto:avrPto-mediated hypersensitive response in disease resistance. These results demonstrate that SA may act through multiple effector proteins in plants and shed further light on the function of CA in chloroplasts.
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Claims 8
Claim · model-written summary
SABP3 binds salicylic acid with an apparent dissociation constant of 3.7 microM
- Taxon
- tobacco
Nicotiana tabacume1 - Gene
- SABP3e2
- Compound
- SAe2
- Outcome
- dissociation constante2
- Value
- 3.7 microMe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts”
e2“SABP3 bound SA with an apparent dissociation constant (K(d)) of 3.7 microM”
Claim · model-written summary
SABP3 has much greater affinity for biologically active than for inactive SA analogs
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- biologically activee3
- Outcome
- affinitye3
- Direction
- greatere3
- Comparator
- inactive analogse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts”
e3“exhibited much greater affinity for biologically active than inactive analogs”
Claim · model-written summary
SABP3 is the chloroplast carbonic anhydrase
- Taxon
- tobaccoNicotiana tabacume1
- Gene
- SABP3e4
- Outcome
- chloroplast carbonic anhydrasee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts”
e4“Purification and partial sequencing of SABP3 indicated that it is the chloroplast carbonic anhydrase (CA)”
Claim · model-written summary
Recombinant tobacco chloroplast CA has both carbonic anhydrase enzymatic activity and SA-binding activity
- Taxon
- tobaccoNicotiana tabacume5
- Compound
- SAe5
- Outcome
- CA enzymatic and SA-binding activitiese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“recombinant tobacco chloroplast CA exhibited both CA enzymatic and SA-binding activities”
Claim · model-written summary
Expression of CA/SABP3 in yeast shows antioxidant activity
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- Expression of this protein in yeaste6
- Gene
- CA/SABP3e6
- Outcome
- antioxidant activitye6
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts”
e6“Expression of this protein in yeast also demonstrated that CA/SABP3 has antioxidant activity”
Claim · model-written summary
A second CA-encoding gene gives a protein that behaves similarly to SABP3
- Taxon
- tobaccoNicotiana tabacume1
- Gene
- gene encoding CAe7
- Outcome
- behave similarly to that purified as SABP3e7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts”
e7“A second gene encoding CA was also cloned, and its encoded protein was shown to behave similarly to that purified as SABP3”
Claim · model-written summary
Silencing CA gene expression in leaves suppresses the Pto:avrPto-mediated hypersensitive response
- Taxon
- tobaccoNicotiana tabacume1
- Organ / stage
- leavese0
- Treatment
- silencing of CA gene expressione0
- Gene
- CAe0
- Outcome
- Pto:avrPto-mediated hypersensitive responsee0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Here we describe the identification of an SA-binding protein, SABP3, in the stroma of tobacco chloroplasts”
e0“silencing of CA gene expression in leaves suppressed the Pto:avrPto-mediated hypersensitive response in disease resistance”
Claim · model-written summary
SA may act through multiple effector proteins in plants
- Taxon
- plantsViridiplantaee0
- Compound
- SAe0
- Outcome
- multiple effector proteinse0
Verbatim
e0“SA may act through multiple effector proteins in plants”
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