This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Prado-Cabrero, A.
Right arrow Articles by Al-Babili, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Prado-Cabrero, A.
Right arrow Articles by Al-Babili, S.

 Previous Article  |  Next Article 

Eukaryotic Cell, April 2007, p. 650-657, Vol. 6, No. 4
1535-9778/07/$08.00+0     doi:10.1128/EC.00392-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Retinal Biosynthesis in Fungi: Characterization of the Carotenoid Oxygenase CarX from Fusarium fujikuroi{triangledown}

Alfonso Prado-Cabrero,1 Daniel Scherzinger,2 Javier Avalos,1 and Salim Al-Babili2*

Faculty of Biology, Albert-Ludwigs University of Freiburg, Schaenzlestr. 1, D-79104 Freiburg, Germany,2 Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain1

Received 8 December 2006/ Accepted 4 February 2007

The car gene cluster of the ascomycete Fusarium fujikuroi encodes two enzymes responsible for torulene biosynthesis (CarRA and CarB), an opsin-like protein (CarO), and a putative carotenoid cleaving enzyme (CarX). It was presumed that CarX catalyzes the formation of the major carotenoid in F. fujikuroi, neurosporaxanthin, a cleavage product of torulene. However, targeted deletion of carX did not impede neurosporaxanthin biosynthesis. On the contrary, {Delta}carX mutants showed a significant increase in the total carotenoid content, indicating an involvement of CarX in the regulation of the pathway. In this work, we investigated the enzymatic activity of CarX. The expression of the enzyme in ß-carotene-accumulating Escherichia coli cells led to the formation of the opsin chromophore retinal. The identity of the product was proven by high-performance liquid chromatography and gas chromatography-mass spectrometry. Subsequent in vitro assays with heterologously expressed and purified CarX confirmed its ß-carotene-cleaving activity and revealed its capability to produce retinal also from other substrates, such as {gamma}-carotene, torulene, and ß-apo-8'-carotenal. Our data indicate that the occurrence of at least one ß-ionone ring in the substrate is required for the cleavage reaction and that the cleavage site is determined by the distance to the ß-ionone ring. CarX represents the first retinal-synthesizing enzyme reported in the fungal kingdom so far. It seems likely that the formed retinal is involved in the regulation of the carotenoid biosynthetic pathway via a negative feedback mechanism.

* Corresponding author. Mailing address: Faculty of Biology, Albert-Ludwigs University of Freiburg, Schaenzlestr. 1, D-79104 Freiburg, Germany. Phone: 49 761 203 8454. Fax: 49 761 203 2675. E-mail: salim.albabili{at}biologie.uni-freiburg.de

{triangledown} Published ahead of print on 9 February 2007.

Eukaryotic Cell, April 2007, p. 650-657, Vol. 6, No. 4
1535-9778/07/$08.00+0     doi:10.1128/EC.00392-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Rodriguez-Ortiz, R., Limon, M. C., Avalos, J. (2009). Regulation of Carotenogenesis and Secondary Metabolism by Nitrogen in Wild-Type Fusarium fujikuroi and Carotenoid-Overproducing Mutants. Appl. Environ. Microbiol. 75: 405-413 [Abstract] [Full Text]  


Copyright © 2010 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»