Open AccessOrganization and regulation of cbb CO 2 assimilation genes in autotrophic bacteria
Author(s) -
Kusian Bernhard,
Bowien Botho
Publication year - 1997
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.1997.tb00348.x
Subject(s) - operon , biology , autotroph , gene , regulator gene , genetics , archaea , transcriptional regulation , obligate , regulation of gene expression , bacteria , biochemistry , gene expression , escherichia coli , ecology
The Calvin‐Benson‐Bassham cycle constitutes the principal route of CO 2 assimilation in aerobic chemoautotrophic and in anaerobic phototrophic purple bacteria. Most of the enzymes of the cycle are found to be encoded by cbb genes. Despite some conservation of the internal gene arrangement cbb gene clusters of the various organisms differ in size and operon organization. The cbb operons of facultative autotrophs are more strictly regulated than those of obligate autotrophs. The major control is exerted by the cbbR gene, which codes for a transcriptional activator of the LysR family. This gene is typically located immediately upstream of and in divergent orientation to the regulated cbb operon, forming a control region for both transcriptional units. Recent studies suggest that additional protein factors are involved in the regulation. Although the metabolic signal(s) received by the regulatory components of the operons is (are) still unknown, the redox state of the cell is believed to play a key role. It is proposed that the control of cbb operon expression is integrated into a regulatory network.