ISSN:
1574-6968
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
In the cyanobacterium Synechocystis sp. strain PCC6803 photosynthetic and respiratory electron transport chains are closely linked and share common components, among them cytochrome c553, plastocyanin, and possibly cytochrome cM. In order to characterize their function more closely, mutants were constructed that lack the genes for one or more of these proteins in both wild-type and coxBAC− (coding for cytochrome c oxidase) backgrounds. Not all constructions led to homozygous strains, especially the joint inactivation of the petJ (cytochrome c553) and petE (plastocyanin) genes or petE and cytM (cytochrome cM) genes proved impossible. The capacity for chemoheterotrophic growth is strictly coupled to the presence of the coxBAC locus. Since even a strain with an intact coxBAC locus but lacking both cytochrome c's grows chemoheterotrophically, plastocyanin or an unidentified substance might be a possible donor to cytochrome c oxidase in this strain. Respiration in strains lacking both the coxBAC locus and the petJ gene is completely inhibitable by HQNO or pentachlorophenol. Since the cytochrome b6f complex is not sensitive to HQNO, the sole respiratory terminal oxidase in these strains is apparently the cytochrome bd quinol oxidase (known to be sensitive to HQNO and pentachlorophenol in Escherichia coli) so far characterized only by DNA sequencing. As respiration in a strain lacking only the coxBAC locus is partially sensitive to HQNO, the non-inhibitable part of the electron transport is identified with a respiratory chain ending in the ARTO, the third respiratory terminal oxidase identified through the total sequence of Synechocystis sp. PCC6803, thus providing for the first time evidence for in vivo activity of all three putative respiratory terminal oxidases.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1574-6968.1997.tb10412.x
