TY - JOUR
T1 - Identification and expression of a soybean nodule-enhanced PEP-carboxylase kinase gene (NE-PpcK) that shows striking up-/down-regulation in vivo
AU - Xu, Wenxin
AU - Zhou, You
AU - Chollet, Raymond
PY - 2003/5
Y1 - 2003/5
N2 - Various isoforms of plant phosphoenolpyruvate carboxylase (PEPC (Ppc)) are controlled post-translationally by an intricate interaction between allosteric regulation and reversible protein phosphorylation. In leaves and root nodules of legumes, these changes in PEPC phosphorylation state are governed primarily by PEPC-kinase (PpcK), a novel, 'minimal but functional' Ser/Thr kinase. To date, this plant-specific kinase has been investigated in molecular terms exclusively in non-leguminous plants, such as Crassulacean-acid-metabolism (CAM) species and Arabidopsis. As an important extension of our earlier biochemical studies on this dedicated kinase and PEPC phosphorylation in soybean (Glycine max) nodules, we now report the molecular cloning of the first legume PpcK from a soybean nodule cDNA library, which encodes a functional, 31.0 kDa PpcK polypeptide. Besides displaying organ, developmental, and spatial expression properties that are strikingly up-regulated in mature nodules, the expression pattern of this transcript is distinct from that of a second soybean PpcK isogene (GmPpcK). The steady-state abundance of this former, nodule-enhanced transcript (NE-PpcK) is markedly influenced by photosynthate supply from the shoots. This latter up-/down-regulation of NE-PpcK transcript level occurs in vivo in concert with the corresponding changes in the nodule PpcK activity, the phosphorylation-state of PEPC, and the abundance of a previously identified, nodule-enhanced transcript (GmPEPC7) that encodes the target enzyme (NE-Ppc). Furthermore, genomic Southern analysis and inspection of the public database indicate that there are at least three distinct PpcK and Ppc isogenes in soybean. Collectively, these and recent findings with Arabidopsis implicate the existence of multiple PpcK-Ppc 'expression-partners' in plants, exemplified by NE-PpcK and NE-Ppc in the soybean nodule.
AB - Various isoforms of plant phosphoenolpyruvate carboxylase (PEPC (Ppc)) are controlled post-translationally by an intricate interaction between allosteric regulation and reversible protein phosphorylation. In leaves and root nodules of legumes, these changes in PEPC phosphorylation state are governed primarily by PEPC-kinase (PpcK), a novel, 'minimal but functional' Ser/Thr kinase. To date, this plant-specific kinase has been investigated in molecular terms exclusively in non-leguminous plants, such as Crassulacean-acid-metabolism (CAM) species and Arabidopsis. As an important extension of our earlier biochemical studies on this dedicated kinase and PEPC phosphorylation in soybean (Glycine max) nodules, we now report the molecular cloning of the first legume PpcK from a soybean nodule cDNA library, which encodes a functional, 31.0 kDa PpcK polypeptide. Besides displaying organ, developmental, and spatial expression properties that are strikingly up-regulated in mature nodules, the expression pattern of this transcript is distinct from that of a second soybean PpcK isogene (GmPpcK). The steady-state abundance of this former, nodule-enhanced transcript (NE-PpcK) is markedly influenced by photosynthate supply from the shoots. This latter up-/down-regulation of NE-PpcK transcript level occurs in vivo in concert with the corresponding changes in the nodule PpcK activity, the phosphorylation-state of PEPC, and the abundance of a previously identified, nodule-enhanced transcript (GmPEPC7) that encodes the target enzyme (NE-Ppc). Furthermore, genomic Southern analysis and inspection of the public database indicate that there are at least three distinct PpcK and Ppc isogenes in soybean. Collectively, these and recent findings with Arabidopsis implicate the existence of multiple PpcK-Ppc 'expression-partners' in plants, exemplified by NE-PpcK and NE-Ppc in the soybean nodule.
KW - Nodule-enhanced PEPC-kinase
KW - PEPC
KW - PpcK
KW - Protein phosphorylation
KW - Root nodules
KW - Ser/Thr kinase
KW - Soybean (Glycine max)
UR - http://www.scopus.com/inward/record.url?scp=0038751865&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0038751865&partnerID=8YFLogxK
U2 - 10.1046/j.1365-313X.2003.01740.x
DO - 10.1046/j.1365-313X.2003.01740.x
M3 - Article
C2 - 12753584
AN - SCOPUS:0038751865
VL - 34
SP - 441
EP - 452
JO - Plant Journal
JF - Plant Journal
SN - 0960-7412
IS - 4
ER -