Publications

• Advances in steroidal saponins biosynthesis.

  Chen Y., Wu J., Yu D., Du X.

  <h4>Main conclusion</h4>This work reviews recent advances in the pathways and key enzymes of steroidal saponins biosynthesis and sets the foundation for the biotechnological production of these useful compounds through transformation of microorganisms. Steroidal saponins, due to their specific che ... >> More

  <h4>Main conclusion</h4>This work reviews recent advances in the pathways and key enzymes of steroidal saponins biosynthesis and sets the foundation for the biotechnological production of these useful compounds through transformation of microorganisms. Steroidal saponins, due to their specific chemical structures and active effects, have long been important natural products and that are irreplaceable in hormone production and other pharmaceutical industries. This article comprehensively reviewed the previous and current research progress and summarized the biosynthesis pathways and key biosynthetic enzymes of steroidal saponins that have been discovered in plants and microoganisms. On the basis of the general biosynthetic pathway in plants, it was found that the starting components, intermediates and catalysing enzymes were diverse between plants and microorganisms; however, the functions of their related enzymes tended to be similar. The biosynthesis pathways of steroidal saponins in microorganisms and marine organisms have not been revealed as clearly as those in plants and need further investigation. The elucidation of biosynthetic pathways and key enzymes is essential for understanding the synthetic mechanisms of these compounds and provides researchers with important information to further develop and implement the massive production of steroidal saponins by biotechnological approaches and methodologies. << Less

  Planta 254:91-91(2021) [PubMed] [EuropePMC]

• Cloning and functional analysis of two sterol-C24-methyltransferase 1 (SMT1) genes from Paris polyphylla.

  Guan H.Y., Su P., Zhao Y.J., Zhang X.N., Dai Z.B., Guo J., Tong Y.R., Liu Y.J., Hu T.Y., Yin Y., Gao L.H., Gao W., Huang L.Q.

  The biosynthetic pathways of phytosterols and steroidal saponins are located in two adjacent branches which share cycloartenol as substrate. The rate-limiting enzyme S-adenosyl-L-methionine-sterol-C24-methyltransferase 1 (SMT1) facilitates the metabolic flux toward phytosterols. It catalyzes the m ... >> More

  The biosynthetic pathways of phytosterols and steroidal saponins are located in two adjacent branches which share cycloartenol as substrate. The rate-limiting enzyme S-adenosyl-L-methionine-sterol-C24-methyltransferase 1 (SMT1) facilitates the metabolic flux toward phytosterols. It catalyzes the methylation of the cycloartenol in the side chain of the C24-alkyl group, to generate 24(28)-methylene cycloartenol. In this study, we obtained two full-length sequences of SMT1 genes from Pari polyphylla, designated PpSMT1-1 and PpSMT1-2. The full-length cDNA of PpSMT1-1 was 1369 bp long with an open reading frame (ORF) of 1038 bp, while the PpSMT1-2 had a length of 1222 bp, with a 1005 bp ORF. Bioinformatics analysis confirmed that the two cloned SMTs belong to the SMT1 family. The predicted function was further validated by performing in vitro enzymatic reactions, and the results showed that PpSMT1-1 encodes a cycloartenol-C24-methyltransferase, which catalyzes the conversion of cycloartenol to 24-methylene cycloartenol, whereas PpSMT1-2 lacked this catalytic activity. The tissue expression patterns of the two SMTs revealed differential expression in different organs of Paris polyphylla plants of different developmental stage and age. These results lay the foundation for detailed genetic studies of the biosynthetic pathways of steroid compounds, which constitute the main class of active substances found in P. polyphylla. << Less

  J Asian Nat Prod Res 20:595-604(2018) [PubMed] [EuropePMC]

• Two families of sterol methyltransferases are involved in the first and the second methylation steps of plant sterol biosynthesis.

  Bouvier-Nave P., Husselstein T., Benveniste P.

  Two methyl transfers are involved in the biosynthesis of 24-methyl and 24-ethyl sterols, which play major roles in plant growth and development. The first methyl transfer applies to cycloartenol, the second to 24-methylene lophenol. About ten cDNA clones encoding S-adenosyl-L-methionine (AdoMet) s ... >> More

  Two methyl transfers are involved in the biosynthesis of 24-methyl and 24-ethyl sterols, which play major roles in plant growth and development. The first methyl transfer applies to cycloartenol, the second to 24-methylene lophenol. About ten cDNA clones encoding S-adenosyl-L-methionine (AdoMet) sterol methyltransferases (SMTs) have been isolated so far from various plants. According to their deduced amino acid sequences, they were classified in two families, smtl and smt2; in addition, smt2 cDNAs were shown to encode a 24-methylene lophenol C24 methyltransferase [Bouvier-Navé, P., Husselstein, T., Desprez, T. & Benveniste, P. (1997) Eur. J. Biochem. 246, 518-529]. We now report the comparison of two cDNAs isolated from Nicotiana tabacum, Ntsmt1-1 which belongs to the first SMT cDNA family and Ntsmt2-1 which belongs to the second. Both cDNAs were expressed in the yeast null mutant erg6, deficient in SMT. Whereas erg6 is devoid of 24-alkyl sterols, erg6 Ntsmt1-1 contained a majority of 24-methylene sterols and erg6 Ntsmt2-1, a majority of 24-ethylidene sterols, indicating distinct functions for the expression products of these cDNAs. In the presence of AdoMet, delipidated microsomes from erg6 Ntsm1-1 efficiently converted cycloartenol into 24-methylene cycloartanol, but did not produce any 24-ethylidene lophenol upon incubation with 24-methylene lophenol. This demonstrates that cDNA Ntsmt1-1 (and most probably the other plant SMT cDNAs of the first family) encode(s) a cycloartenol C24 methyltransferase. In contrast, delipidated microsomes of erg6 Ntsmt2-1 were shown to methylate preferentially 24-methylene lophenol, as expected from an SMT encoded by an smt2 cDNA. In summary, among various cDNAs isolated from N. tabacum, one (Ntsmt1-1) belongs to the first family of plant SMT cDNAs according to its deduced amino acid sequence and was shown to encode a cycloartenol C24 methyltransferase, whereas another (Ntsmt2-1) belongs to the second family and was shown to encode a 24-methylene lophenol C24 methyltransferase. Meanwhile, two cDNAs were isolated from Oriza sativa and shown to belong to smtl and to smt2 families, respectively. These data disclose the coexistence, in a given plant species, of two distinct SMTs, each catalyzing one step of methylation in the sterol biosynthesis pathway. << Less

  Eur. J. Biochem. 256:88-96(1998) [PubMed] [EuropePMC]

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