In:
Scientific Reports, Springer Science and Business Media LLC, Vol. 6, No. 1 ( 2016-09-14)
Abstract:
Paralogous members of the oxidosqualene cyclase (OSC) family encode a diversity of enzymes that are important in triterpenoid biosynthesis. This report describes the isolation of the Gentiana straminea gene GsAS2 that encodes a β - amyrin synthase ( β AS) enzyme. Unlike its previously isolated paralog GsAS1, GsAS2 lacks introns. Its predicted protein product was is a 759 residue polypeptide that shares high homology with other known β -amyrin synthases ( β ASs). Heterologously expressed GsAS2 generates more β -amyrin in yeast than does GsAS1 . Constitutive over-expression of GsAS2 resulted in a 5.7 fold increase in oleanolic acid accumulation, while over-expression of GsAS1 led to a 3 fold increase. Additionally, RNAi-directed suppression of GsAS2 and GsAS1 in G. straminea decreased oleonolic acid levels by 65.9% and 21% respectively, indicating that GsAS2 plays a more important role than GsAS1 in oleanolic acid biosynthesis in G. straminea . We uses a docking model to explore the catalytic mechanism of GsAS1/2 and predicted that GsAS2, with its Y560, have higher efficiency than GsAS1 and mutated versions of GsAS2 in β -amyrin produce. When the key residue in GsAS2 was mutagenized, it produced about 41.29% and 71.15% less β -amyrin than native, while the key residue in GsAS1 was mutagenized to that in GsAS2, the mutant produced 38.02% more β -amyrin than native GsAS1.
Type of Medium:
Online Resource
ISSN:
2045-2322
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2016
detail.hit.zdb_id:
2615211-3
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