Molecular Cloning of Plant Spermidine Synthases

Abstract

Four cDNAs for spermidine synthase (SPDS), which converts the diamine putrescine to the higher polyamine spermidine using decarboxylated S-adenosylmethionine as the co-factor, were isolated from Nicotiana sylvestris, Hyoscyamus niger, and Arabidopsis thaliana. When the N.sylvestris SPDS cDNA was expressed in a SPDS-deficient E. coli mutant, the recombinant protein showed high SPDS activity, but did not have any spermine synthase activity. The plant SPDSs have molecular masses of about 34 kDa, possess the co-factor binding motifs which have been proposed for S-adenosylmethionine, and are more homologous in amino acid sequence to tobacco putrescine N-methyltransferase (PMT) than to SPDSs from mammals and E. coli. The SPDS gene is expressed in root, stem, and leaf in N.sylvestris, whereas the PMT gene is expressed only in root. The potential evolution of plant SPDS and PMT, and their evolutionary relationships with animal SPDS are discussed.

Characterization of the spermidine synthase‐related gene family in Arabidopsis thaliana

“…These include ACL5, which has been shown to encode spermine synthase [11], and two genes whose mRNA sequences have been registered as SPDS1 and SPDS2 (accession numbers AJ251296 and AJ251297). A partial cDNA sequence of SPDS2 has also been reported by Hashimoto et al [16]. An additional gene was found to be located on chromosome 5.…”

Improvement of environmental stress tolerance of sweet potato by introduction of genes for spermidine synthase

“…The gene, designated as FSPD1 (GenBank accession No. BD142348), shares 84% homology in the deduced nucleotide sequence with Arabidopsis SPDS cDNA (Hashimoto et al 1998).…”

Cloning of nicotianamine synthase genes fromArabidopsis thaliana

“…Kagan and Clarke (1994) and Joshi and Chiang (1998) proposed the SAM binding site based on a computer analysis of the amino acid sequences of SAM-dependent methyltransferases that use SAM as a substrate. Schluckebier et al (1995) and Hashimoto et al (1998) also examined the common catalytic domain of spermidine synthase and spermine synthase, which both use decarboxy-SAM as a substrate, in terms of amino acid sequences. Of the conserved regions in the NAS protein, residues 136-145 (Fig.…”