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JOURNAL OF BACTERIOLOGY, Mar. 2004, p. 15311536 Vol. 186, No. 5 0021-9193/04/$08.00 0 DOI: 10.1128/JB.186.5.15311536.2004
 

Summary: JOURNAL OF BACTERIOLOGY, Mar. 2004, p. 15311536 Vol. 186, No. 5
0021-9193/04/$08.00 0 DOI: 10.1128/JB.186.5.15311536.2004
Copyright 2004, American Society for Microbiology. All Rights Reserved.
Evolution of a Pathway to Novel Long-Chain Carotenoids
Daisuke Umeno* and Frances H. Arnold
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena,
California 91125
Received 5 June 2003/Accepted 30 October 2003
Using methods of laboratory evolution to force the C30 carotenoid synthase CrtM to function as a C40
synthase, followed by further mutagenesis at functionally important amino acid residues, we have discovered
that synthase specificity is controlled at the second (rearrangement) step of the two-step reaction. We used this
information to engineer CrtM variants that can synthesize previously unknown C45 and C50 carotenoid
backbones (mono- and diisopentenylphytoenes) from the appropriate isoprenyldiphosphate precursors. With
this ability to produce new backbones in Escherichia coli comes the potential to generate whole series of novel
carotenoids by using carotenoid-modifying enzymes, including desaturases, cyclases, hydroxylases, and dioxy-
genases, from naturally occurring pathways.
Carotenoids are natural pigments with important biological
activities (4, 10, 16, 17). Most are based on a 40-carbon (C40)
phytoene backbone produced by condensation of 2 molecules
of geranylgeranyldiphosphate (GGDP; C20PP), a reaction cat-

  

Source: Arnold, Frances H. - Division of Chemistry and Chemical Engineering, California Institute of Technology

 

Collections: Chemistry; Biology and Medicine