Molecular cloning and characterization of coffee cDNA encoding spermidine synthase

A cDNA for spermidine synthase (SPDS), which converts putrescine to spermidine using decarboxylated S-adenosylmethionine as a co-factor, has been isolated from Coffea arabica. When the SPDS cDNA is expressed in an SPDS-deficient E. coli mutant: the recombinant protein shows high SPDS activity. The C. arabica SPDS possesses the co-factor binding motifs which have been proposed for S-adenosylmethionine, and its amino acid sequence is similar to other plant SPDSs. The SPDS transcripts have been observed in roots, green stems, old and young leaves, and accumulated to a higher level in rapid growing tissues, such as green stems and younger leaves, compared to old leaves. In callus tissues, it has been expressed in all stages, even though callus growth is very slow during somatic embryogenesis. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.