High impact information on NDPK2

• Depending on the specific serine residues dephosphorylated by PAPP5, phytochrome stability and affinity for a downstream signal transducer, NDPK2, were enhanced [1].
• These results indicate that NDPK2 is a positive signalling component of the phytochrome-mediated light-signal-transduction pathway in Arabidopsis [2].
• The phosphorylation at Ser598 prevented its interaction with putative signal transducers, Nucleoside Diphosphate Kinase-2 and Phytochrome-Interacting Factor-3 [3].
• H(2)O(2) stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2) [4].
• Furthermore, AtNDPK2 also enhances the myelin basic protein phosphorylation activity of AtMPK3 in vitro [4].

Biological context of NDPK2

• Domain studies revealed that PER-ARNT-SIM domain A in the C-terminal domain of phytochrome is the binding site for NDPK2 [5].
• Of the three NDPKs (NDPK1-NDPK3) expressed in Arabidopsis thaliana, NDPK2 is involved in phytochrome-mediated signal transduction [6].
• A possible role for NDPK2 in the regulation of auxin-mediated responses for plant growth and development [7].
• In the absence of H(2)O(2) treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased in the AtNDPK2 deletion mutant [4].
• A new type of nucleotide diphosphate kinase (NDPK Ia) with a significant homology to the human tumor suppressor protein Nm23 rescued the gcn4 phenotype [8].

Anatomical context of NDPK2

• In Arabidopsis, the NDPK Ia protein is located in the nucleus and cytosol [8].

Associations of NDPK2 with chemical compounds

• Further studies indicated that the low enzymatic activity and autophosphorylation level of NDPK2 mutant S199A are shown to be due to a damaged H-bonding with the active histidine residue His197 in the nucleotide-binding pocket [9].
• To resolve the controversy of whether serine/threonine phosphorylation of NDPK occurs as has been suggested by other NDPK studies, NDPK2 putative phosphorylation site mutants were generated and examined [9].

Other interactions of NDPK2

• The structure of Arabidopsis NDPK1 and NDPK2 showed that the isoforms share common electrostatic surfaces at the nucleotide-binding site, but the variable C-terminal regions have distinct electrostatic charge distributions [6].
• These results collectively suggest that NDPK2 appears to participate in auxin-regulated processes, partly through the modulation of auxin transport [7].
• Expression studies in seedlings revealed that the level of NDPK Ia mRNA, like that of HDH, increases in response to UV-B light [8].

References