Open AccessCarbon dioxide fixation in ‘ Archaeoglobus lithotrophicus ’: are there multiple autotrophic pathways?
Author(s) -
Estelmann Sebastian,
RamosVera Walter Hugo,
Gad'on Nasser,
Huber Harald,
Berg Ivan A.,
Fuchs Georg
Publication year - 2011
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2011.02268.x
Subject(s) - carbon fixation , autotroph , rubisco , pyruvate carboxylase , biochemistry , dehydratase , ribulose , carbon dioxide , chemistry , enzyme , obligate , citric acid cycle , metabolic pathway , biology , photosynthesis , botany , bacteria , genetics , organic chemistry
Several representatives of the euryarchaeal class Archaeoglobi are able to grow facultative autotrophically using the reductive acetyl‐CoA pathway, with ‘ Archaeoglobus lithotrophicus ’ being an obligate autotroph. However, genome sequencing revealed that some species harbor genes for key enzymes of other autotrophic pathways, i.e. 4‐hydroxybutyryl‐CoA dehydratase of the dicarboxylate/hydroxybutyrate cycle and the hydroxypropionate/hydroxybutyrate cycle and ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) of the Calvin–Benson cycle. This raised the question of whether only one or multiple autotrophic pathways are operating in these species. We searched for the presence of enzyme activities specific for the dicarboxylate/hydroxybutyrate or the hydroxypropionate/hydroxybutyrate cycles in ‘ A. lithotrophicus ’, but such enzymes could not be detected. Low Rubisco activity was detected that could not account for the carbon dioxide (CO 2 ) fixation rate; in addition, phosphoribulokinase activity was not found. The generation of ribulose 1,5‐bisphosphate from 5‐phospho‐ d ‐ribose 1‐pyrophosphate was observed, but not from AMP; these sources for ribulose 1,5‐bisphosphate have been proposed before. Our data indicate that the reductive acetyl‐CoA pathway is the only functioning CO 2 fixation pathway in ‘ A. lithotrophicus ’.