Cloning,expression and characterization of a nucleoside diphosphate kinase (NDPK) gene from tobacco

Nucleoside diphosphate kinase (NDPK) is a housekeeping enzyme that maintains the intracellular levels of all (d)NTPs used in biosynthesis except ATP.Here we report that a full-length cDNA encoding nucleoside diphosphate kinase (NDPK) was cloned us- ing yeast two-hybrid approach.A tobacco NDPK gene was obtained and designated as NtNDPK1.NtNDPK1 is 704 bp in length and en- codes a putative 16.2 kD protein of 148 amino acids.Phylogenic analysis showed that NtNDPK1 is highly homologous to other plant NDPK genes and identified as type I (NDPK1).RNA-gel blot analysis showed that there was no significant difference of NtNDPK1 ex- pression in roots,stems,leaves and buds.And expression of NtNDPK1 was induced by ABA and PEG and repressed by NaCl,but not significantly affected by Paraquat,wounding and low temperature (4℃) treatments,indicating that NtNDPK1 may play a certain role in response to abiotic stress.In vitro phosphorylation assay demonstrated that NtNDPK1 had autophosphoryLation activity.