Objective Sequence of the gene associated with the key enzyme in sucrose metabolism pathway of potatoes, sucrose synthase (SuSy), was determined for studying the biological function of the enzyme.
Method The core fragment (PGSC0003DMG400002895, SuSy 4) of SuSy was screened from the transcriptome database on the plantlets of Alpine potatoes (Solanum tuberosum L. cv. Huaiyushan). The gene was cloned by RT-PCR, and its sequence analyzed using the bioinformatics method.
Result The total length of cDNA of SuSy gene was 2 418 bp containing 45.08% of G+C. The hydrophilic protein had 805 amino acids with a molecular weight of 92 471.33 Da and an isoelectric point of 5.87. Its secondary structure was 45.84% of alpha helix, 15.16% of β -extended strands, and 39.01% of random coils. The β-lamellae and α-helix were found throughout the entire protein but appeared as irregular, curl, extension chains at the C- and N-terminals. The tetrameric gene mainly existed in the cytoplasm, mitochondria, and chloroplast. It closely related to those of S. lycopersicum, S. pennellii, S. chilense, S. tuberosum, Capsicum annuum, and C. baccatum in evolution, especially, S. tuberosum.
Conclusion The SuSy gene in the Alpine potato of Huaiyushan had the characteristic structure of a typical sucrose synthase. The amino acid and nucleic acid sequences were highly conserved and homologous to the similar species. The findings would be of great significance for further understanding on the biological function of the enzyme.
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