1. Regulatory Circuits Controlling Photosynthesis Gene Expression
Carl E Bauer, Terry H Bird 
Cell 
Volume 85, Issue 1, Pages 5-8 (April 1996)
DOI: /S (00)

2. Figure 1
Genetic and Biochemical Features of the Rhodobacter capsulatus Photosystem
Bottom section depicts the photosynthesis gene cluster which codes for bacteriochlorophyll biosynthesis (green), carotenoid biosynthesis (orange), reaction center (red) and light harvesting (blue) genes. Unlinked to the photosynthesis gene cluster is the puc operon encoding the light harvesting-II structural polypeptides. Arrows denote mRNA produced from the superoperons (light) or the vigorously transcribed puf, puh, and puc operons (heavy). Middle section shows the molecular structures of bacteriochlorophyll a (green) and the predominant carotenoid, spheroidenone (orange). The red and blue structures represent membrane spanning polypeptides of the reaction center and light harvesting complexes, respectively. Top section is a cutaway diagram of the intracytoplasmic membrane which houses the photosystem.
Cell  , 5-8DOI: ( /S (00) )

3. Figure 2
Regulatory Circuits Controlling Photosynthesis Gene Expression
(A) Bacteriochlorophyll, carotenoid and light harvesting-II (puc) transcripts are repressed by CrtJ (gray box) under aerobic growth conditions (green circuit).
(B) Light harvesting-I and reaction center genes (puh and puf) as well as the light harvesting-II structural genes are transactivated under anaerobic conditions by a multi-component signal transduction pathway (red circuit). RegX represents a hypothetical downstream component of the RegB-RegA signal transduction pathway that is believed to interact with an unspecified alternative sigma factor (σP) during transcription of the puf and puh operons (see text).
(C) Under anaerobic dim light conditions the transactivator HvrA stimulates high level expression of the puf and puh operons (blue circuit).
Cell  , 5-8DOI: ( /S (00) )

4. Figure 3 Complexity of the Photosynthesis Regulatory Network
Superimposing the three regulatory circuits (as described in Figure 2) on the overlapping transcription units of the superoperons emphasizes the complexities involved in coordinating expression of photopigment biosynthesis genes with those of the light harvesting and reaction center structural genes.
Cell  , 5-8DOI: ( /S (00) )