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Journal of Bacteriology, May 2009, p. 3292-3300, Vol. 191, No. 10
0021-9193/09/$08.00+0     doi:10.1128/JB.00050-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

The Biosynthetic Pathway for Myxol-2' Fucoside (Myxoxanthophyll) in the Cyanobacterium Synechococcus sp. Strain PCC 7002{triangledown} ,{dagger}

Joel E. Graham{ddagger} and Donald A. Bryant*

Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802

Received 15 January 2009/ Accepted 12 March 2009

Synechococcus sp. strain PCC 7002 produces a variety of carotenoids, which comprise predominantly dicylic β-carotene and two dicyclic xanthophylls, zeaxanthin and synechoxanthin. However, this cyanobacterium also produces a monocyclic myxoxanthophyll, which was identified as myxol-2' fucoside. Compared to the carotenoid glycosides produced by diverse microorganisms, cyanobacterial myxoxanthophyll and closely related compounds are unusual because they are glycosylated on the 2'-OH rather than on the 1'-OH position of the {psi} end of the molecule. In this study, the genes encoding two enzymes that modify the {psi} end of myxoxanthophyll in Synechococcus sp. strain PCC 7002 were identified. Mutational and biochemical studies showed that open reading frame SynPCC7002_A2032, renamed cruF, encodes a 1'-hydroxylase and that open reading frame SynPCC7002_A2031, renamed cruG, encodes a 2'-O-glycosyltransferase. The enzymatic activity of CruF was verified by chemical characterization of the carotenoid products synthesized when cruF was expressed in a lycopene-producing strain of Escherichia coli. Database searches showed that homologs of cruF and cruG occur in the genomes of all sequenced cyanobacterial strains that are known to produce myxol or the acylic xanthophyll oscillaxanthin. The genomes of many other bacteria that produce hydroxylated carotenoids but do not contain crtC homologs also contain cruF orthologs. Based upon observable intermediates, a complete biosynthetic pathway for myxoxanthophyll is proposed. This study expands the suite of enzymes available for metabolic engineering of carotenoid biosynthetic pathways for biotechnological applications.

* Corresponding author. Mailing address: Department of Biochemistry and Molecular Biology, S-235 Frear Building, The Pennsylvania State University, University Park, PA 16802. Phone: (814) 865-1992. Fax: (814) 863-7024. E-mail: dab14{at}psu.edu

{triangledown} Published ahead of print on 20 March 2009.

{dagger} Supplemental material for this article may be found at http://jb.asm.org/.

{ddagger} Present address: Center for Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202.

Journal of Bacteriology, May 2009, p. 3292-3300, Vol. 191, No. 10
0021-9193/09/$08.00+0     doi:10.1128/JB.00050-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Sun, Z., Shen, S., Wang, C., Wang, H., Hu, Y., Jiao, J., Ma, T., Tian, B., Hua, Y. (2009). A novel carotenoid 1,2-hydratase (CruF) from two species of the non-photosynthetic bacterium Deinococcus. Microbiology 155: 2775-2783 [Abstract] [Full Text]  


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