Expression of the chloroplast thioredoxins f and m is linked to short-term changes in the sugar and thiol status in leaves of Pisum sativum.
Thioredoxins (TRXs) f and m are key components in the light regulation of photosynthetic metabolism via thiol-dithiol modulation in chloroplasts of leaves; however, little is known about the factors modulating the expression of these proteins. To investigate the effect of sugars as photosynthetic products on the expression of PsTRX f and m1 genes, sucrose and glucose were externally supplied to pea plants during the day. There was an increase in the mRNA levels of PsTRX f and m1 genes in response mainly to glucose. When leaf discs were incubated for up to 4h in the dark, glucose also led to an increase in both mRNA and protein levels of TRXs f and m, while sucrose had no substantial effect. Expression of PsDOF7, a carbon metabolism-related transcription factor gene, was also induced by glucose. Protein-DNA interaction showed that PsDOF7 binds specifically to the DOF core located in PsTRX f and m1 gene promoters. Transient expression in agroinfiltrated pea leaves demonstrated that PsDOF7 activated transcription of both promoters. The incubation of leaf discs in dithiotreitol (DTT) to increase the redox status led to a marked increase in the mRNA and protein levels of both TRXs within 4h. The increase in TRX protein levels occurred after 1h DTT feeding, implying a rapid effect of the thiol status on TRX f and m1 protein turnover rates, while transcriptional regulation took 3h to proceed. These results show that the protein levels of both TRXs are under short-term control of the sugar and thiol status in plants.
Departamento de Bioquímica, Biología Molecular y Celular de Plantas, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, 18008, Granada, Spain.
Juan
J
de Dios Barajas-López
Justyna
J
Tezycka
Claudia N
CN
Travaglia
Antonio Jesús
AJ
Serrato
Ana
A
Chueca
Ina
I
Thormählen
Peter
P
Geigenberger
Mariam
M
Sahrawy
D000595:Amino Acid Sequence; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000032:analysis / Q000494:pharmacology*; D054479:Chloroplast Thioredoxins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D005632:Fructose / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D015870:Gene Expression; D005947:Glucose / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D018532:Pisum sativum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D015398:Signal Transduction; D013395:Sucrose / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D013438:Sulfhydryl Compounds / Q000378:metabolism*
D002241:Carbohydrates; D054479:Chloroplast Thioredoxins; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D013438:Sulfhydryl Compounds; D005632:Fructose; D013395:Sucrose; D005947:Glucose