‘Every dogma has its day’: a personal look at carbon metabolism in photosynthetic bacteria

Thioredoxin: an unexpected meeting place

“…The acceptance of the work was likely held back by the fact that Calvin, himself, did not believe the evidence for the cycle (Ormerod 2003). However, in the end, other studies, including genome sequencing, confirmed the original observations: the reverse citric acid cycle was the major mechanism of carbon fixation in Chlorobium and the organism lacked the cycle described by the Calvin laboratory (Buchanan and Sirevåg 1976;Sirevåg and Buchanan 1977;Fuchs et al 1980a, b;Ivanovsky et al 1980;Tabita 1988;Buchanan and Arnon 1990;Eisen et al 2002;Ormerod 2003).…”

“…However, in the end, other studies, including genome sequencing, confirmed the original observations: the reverse citric acid cycle was the major mechanism of carbon fixation in Chlorobium and the organism lacked the cycle described by the Calvin laboratory (Buchanan and Sirevåg 1976;Sirevåg and Buchanan 1977;Fuchs et al 1980a, b;Ivanovsky et al 1980;Tabita 1988;Buchanan and Arnon 1990;Eisen et al 2002;Ormerod 2003). According to recent evidence, the reverse citric acid cycle functions more broadly than originally envisaged and is present in a variety of nonphotosynthetic (chemoautotrophic) bacteria, including magnetotactic cocci (Williams et al 2006), and inhabitants of hydrothermal vents (Takai et al 2005;Hügler 2007; and references therein).…”

“…The new Chlorobium pathway, which was worked out jointly with Michael Evans, Daniel Arnon and myself, was the first described as being independent of the cycle identified by Calvin and collaborators for algae and leaves (Bassham et al 1954). As detailed by Ormerod (2003), the work went firmly against entrenched dogma, and, as a consequence, almost 25 years elapsed before the cycle was accepted by the scientific community (Buchanan and Arnon 1990).…”

“…A strain of Chlorobium was recently identified among the inhabitants isolated from the East Pacific Rise-an area of high-volcanic activity with vents that support a variety of ecosystems (Beatty et al 2005). In view of the diversity of microorganisms, it is perhaps not surprising that, since the Chlorobium work, paths of authotrophic carbon dioxide assimilation have been identified that function independently of either the Calvin cycle or the reverse citric acid cycle (Ormerod 2003).…”

Time line of discoveries: anoxygenic bacterial photosynthesis

“…Subsequent research, notably by Sirevåg (1995), provided the missing evidence. See also Ormerod (2003). Don DeVault and Britton Chance report the temperature-independent photooxidation of cytochromes in Chromatium vinosum, the first evidence for quantum mechanical tunneling processes in any biological system (DeVault and Chance 1966).…”