Effect of growth condition on enzymes of the citric acid cycle and the glyoxylate cycle in the photosynthetic bacterium Rhodopseudomonas palustris

Abstract

The enzymes of the citric acid and glyoxylate cycles as well as RuBP4 carboxylase were measured in cell-free extracts from Rhodopseudomonas palustris after growth under chemoheterotrophic, photoheterotrophic and photolithotrophic conditions. Although the citric acid cycle was found to be complete under all growth conditions, significant differences in certain enzyme activities occurred as a function of the different energy sources applied. The glyoxylate cycle also was complete under all growth conditions with highest isocitrate lyase activity seen after photoheterotrophic growth on acetate. Photo- and chemoheterotrophic growth on malate reduced the isocitrate lyase. The activity was not repressed further by photolithotrophic growth on thiosulfate. RuBP carboxylase activity, present under photolithotrophic conditions, was repressed by chemoheterotrophic growth but was not decreased by the presence of organic substrates during photoheterotrophic growth.

The Tricarboxylic Acid Cycle of Heterogeneous and Swarmer Cell Populations of Rhodomicrobium vannielii Rm5

“…vannielii and that repression of 2-oxoglutarate dehydrogenase synthesis under anaerobic conditions is more complete. However, its response to increasing oxygen levels, the production of higher levels of the enzyme, is identical to that observed in other Rhodospirillaceae (Eley et al, 1979;Cox et al, 1983). Under anaerobic conditions the role of the TCA cycle of Rm.…”

“…This observation is similar to those made for other members of the Rhodospirillaceae and also for E. coli under variable growth conditions (Amarasingham & Davis, 1965). However, in the other Rhodospirillaceae even under anaerobic photoheterotrophic growth conditions a low but significant level of 2-oxoglutarate dehydrogenase activity is detectable (Beatty & Gest, 1981a, b ;Eley et al, 1979;Cox et al, 1983). The various lines of evidence suggest that this is not the case in Rm.…”

TCA Cycle Replenishing Pathways in Photosynthetic Purple Non-Sulfur Bacteria Growing with Acetate

“…The purple non-sulfur ICL + bacterium Rps. palustris has been reported to exhibit TCA cycle and glyoxylate cycle enzyme activity when growing in the acetate medium [ 43 ]. TCA cycle and glyoxylate cycle enzymes as well as Rubisco were found to be fully present in cell-free extracts of Rps.…”

“…TCA cycle and glyoxylate cycle enzymes as well as Rubisco were found to be fully present in cell-free extracts of Rps. palustris after growing under chemoheterotrophic, photoheterotrophic and photolithotrophic conditions [ 43 ]. The glyoxylate cycle had the highest ICL activity after photoheterotrophic growth with acetate.…”

GLYOXYLATE CYCLE ENZYME ACTIVITIES IN THE CYANOBACTERIUM ANACYSTIS NIDULANS1

“…(EC.4.1.3.1) and malate synthase (EC.4.1.3.2), have been demonstrated in cell-free extracts from numerous microorganisms (Kornberg and Lascelles 1960, John and Syrett 1967, Peeters et al 1971, Eley et al 1979, Omar and Rehm 1980 where they serve replenishment functions for carbon intermediates common to both the glyoxylate and tricarboxylic acid cycles. However, previous studies on cyanobacteria using cell-free enzyme activities of the glyoxylate cycle enzymes have indicated that the levels of isocitrate lyase and malate synthase were very low compared to other microorganisms Carr 1967, Carr et al 1969).…”