The effect of manganous ions [Mn(II)] and ferrous ions [Fe(II)] on expression of photosynthesis genes in was investigated. The presence of Mn(II) during phototrophic (anaerobic) and chemotrophic (aerobic) growth of caused a decrease in the amount of bacteriochlorophyll and carotenoid pigments which were synthesized and this was associated mainly with a decrease in the level of light-harvesting complex II. Mn(II) was shown to cause a decrease in expression of the operon, which encodes the polypeptides of light-harvesting complex II. Expression of the operon is controlled by the central repressor of photosynthesis gene expression, PpsR. In a mutant there was no effect of Mn(II) on photosynthesis gene expression. It is concluded that Mn(II) may act as a compressor in the action of PpsR or act via an as yet uncharacterized protein that interacts with PpsR. In contrast to the effects of Mn(II), Fe(II) was required for high levels of photosynthesis gene expression. This requirement for Fe(II) was shown to be related to the regulation of , a gene under the control of the transcriptional regulator, FnrL. Mn(II) did not affect FnrL-dependent gene expression.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error