摘要
Methylobacterium species,the representative bacteria distributed in phyllosphere region of plants,often synthesize carotenoids to resist harmful UV radiations.Methylobacterium extorquens is known to produce a carotenoid pigment and recent research revealed that this carotenoid has a C_(30) backbone.However,its exact structure remains unknown.In the present study,the carotenoid produced by M.extorquens AM1 was isolated and its structure was determined as 4-[2-O-11Z-octadecenoyl-β-glucopyranosyl]-4,4′-diapolycopenedioc acid(1),a glycosylated C_(30) carotenoid.Furthermore,the genes related to the C_(30)carotenoid synthesis were investigated.Squalene,the precursor of the C_(30) carotenoid,is synthesized by the co-occurrence of META1p1815,META1p1816 and META1p1817.Further overexpression of the genes related to squalene synthesis improved the titer of carotenoid 1.By using gene deletion and gene complementation experiments,the glycosyltransferase META1p3663 and acyltransferase META1p3664 were firstly confirmed to catalyze the tailoring steps from 4,4′-diapolycopene-4,4′-dioic acid to carotenoid 1.In conclusion,the structure and biosynthetic genes of carotenoid 1 produced by M.extorquens AM1 were firstly characterized in this work,which shed lights on engineering M.extorquens AM1 for producing carotenoid 1 in high yield.
基金
the National Key R&D Program of China(grant No.2021YFC2103500)
National Natural Science Foundation of China(grant No.22078169)
Natural Science Foundation of Shandong Province,China(ZR2021MC074,ZR2020MC008)
Shandong Provincial Key Research and Development Plan(2021ZDSYS28).
