Received June 25, 2003
Accepted August 15, 2003
Lesions in Phycoerythrin Chromophore Biosynthesis in Fremyella diplosiphon
Reveal Coordinated Light Regulation of Apoprotein and Pigment Biosynthetic Enzyme
Gene Expression
Richard M. Alvey 1, Jonathan A. Karty 2, Elicia Roos 1, James P. Reilly 2, and David M. Kehoe 1*
1
Department of Biology, Indiana University, Bloomington, Indiana 47405
2
Department of Chemistry, Indiana University, Bloomington, Indiana 47405
* To whom correspondence should be addressed. E-mail: dkehoe{at}bio.indiana.edu.
We have characterized the regulation of the expression of the pebAB operon,
which encodes the enzymes required for phycoerythrobilin synthesis in the filamentous
cyanobacterium Fremyella diplosiphon. The expression of the pebAB
operon was found to be regulated during complementary chromatic adaptation, the system
that controls the light responsiveness of genes that encode several light-harvesting
proteins in F. diplosiphon. Our analyses of pebA mutants demonstrated
that although the levels of phycoerythrin and its associated linker proteins decreased
in the absence of phycoerythrobilin, there was no significant modulation of the expression
of pebAB and the genes that encode phycoerythrin. Instead, regulation of
the expression of these genes is coordinated at the level of RNA accumulation by
the recently discovered activator CpeR.
