Identification and expression analysis of the cyclophilin gene in Kandelia candel under stress of salt.

Two cDNA fragments, named for SRGKC2 and SRGKC3, encoding cyclophilin in Kandelia candel were isolated by Representational Difference Analysis of cDNA. The two cDNA fragments were 282 bp and 160 bp, respectively. Sequence analysis shows that both of the SRGKC2 and SRGKC3 come from the same gene region, and SRGKC3 is a part of SRGKC2. In addition the SRGKC2 displayed 90% sequence identity over a region of 84 amino acids to the cyclophilin from Euphorbia esula and the SRGKC3 displayed 93% sequence identity over a region of 47 amino acids to the fava bean. The Northern blotting showed that the expression of SRGKC2 was suppressed under stress of salt. Based on the sequence of SRGKC2, a full-length cDNA (KCCYP1) was isolated by RACE reaction (This sequence data has been submitted to the EMBL databases under accession No. AY150052). The full-length cDNA was about 0.9 kb, which contained an open reading frame (ORF) of 516 bp and coded for 172 amino acid residues with isoelectric point of 8.57 and molecular weight of 18.2 kD. The motif A of the ATP/GTP-binding site in KCCYP1 appears at amino acid residues of 41-49, and seven-amino-acids-residue was inserted at 48-54 amino acid residues. The expression patterns of SRGKC2 in various species were also investigated.