首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Carotenoid biosynthesis in <Emphasis Type="Italic">Gloeobacter violaceus</Emphasis> PCC4721 involves a single crtI-type phytoene desaturase instead of typical cyanobacterial enzymes
Authors:Sabine?Steiger  Yvonne?Jackisch  Email author" target="_blank">Gerhard?SandmannEmail author
Institution:(1) Biosynthesis Group, Botanical Institute 213, J.W. Goethe University, P.O. Box 111932, 60054 Frankfurt, Germany
Abstract:Gloeobacter violaceus is a cyanobacterium isolated from other groups by lack of thylakoids and unique structural features of its photosynthetic protein complexes. Carotenoid biosynthesis has been investigated with respect to the carotenoids formed and the genes and enzymes involved. Carotenoid analysis identified ss-carotene as major carotenoid and echinenone as a minor component. This composition is quite unique and the cellular amounts are up to 10-fold lower than in other unicellular cyanobacteria. Carotenoid biosynthesis is up-regulated in a light-dependent manner. This enhanced biosynthesis partially compensates for photooxidation especially of ss-carotene. The sequenced genome of G. violaceus was analyzed and several gene candidates homologous to carotenogenic genes from other organisms obtained. Functional expression of all candidates and complementation in Escherichia coli led to the identification of all genes involved in the biosynthesis of the G. violaceus carotenoids with the exception of the lycopene cyclase gene. An additional diketolase gene was found that functioned in E. coli but is silent in G. violaceus cells. The biggest difference from all other cyanobacteria is the existence of a single bacterial-type 4-step desaturase instead of the poly cis cyanobacterial desaturation pathway catalyzed by two cyanobacterial-type desaturases and an isomerase. The genes for these three enzymes are absent in G. violaceus.
Keywords:Carotenogenic genes  Carotenoid biosynthesis  CrtI-type phytoene desaturase  Echinenone  Light regulation
本文献已被 PubMed SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号