Use of carbon oxysulfide, a structural analog of CO sub 2 , to study active CO sub 2 transport in the cyanobacterium Synechococcus UTEX 625

Journal Article · Sat Jul 01 04:00:00 EDT 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.90.3.1221· OSTI ID:6968377

Miller, A G; Espie, G S; Canvin, D T ^[1]

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1. Queens Univ., Kingston, Ontario (Canada)

Carbon oxysulfide (carbonyl sulfide, COS) is a close structural analog of CO{sub 2}. Although hydrolysis of COS (to CO{sub 2} and H{sub 2}S) does occur at alkaline pH (> 9), at pH 8.0 the rate of hydrolysis is slow enough to allow investigation of COS as a possible substrate and inhibitor of the active CO{sub 2} transport system of Synechococcus UTEX 625. A light-dependent uptake of COS was observed that was inhibited by CO{sub 2} and the ATPase inhibitor diethylstilbestrol. The COS taken up by the cells could not be recovered when the lights were turned off or when acid was added. Bovine erythrocyte carbonic anhydrase catalyzed the stoichiometric hydrolysis of COS to H{sub 2}S. The active transport of CO{sub 2} was inhibited by COS in an apparently competitive manner. When Na{sup +}-dependent HCO{sub 3}{sup {minus}} transport was allowed in the presence of COS, the extracellular (CO{sub 2}) rose considerably above the equilibrium level. This CO{sub 2} appearing in the medium was derived from the dehydration of transported HCO{sub 3}{sup {minus}} and was leaked from the cells. In the presence of COS the return to the cells of this leaked CO{sub 2} was inhibited. These results showed that the Na{sup +}-dependent HCO{sub 3}{sup {minus}} transport was not inhibited by COS, whereas active CO{sub 2} transport was inhibited. The steady state rate of CO{sub 2} fixation was, however, inhibited about 50% in the presence of COS. This inhibition can be at least partially explained by the significant leakage of CO{sub 2} from the cells that occurred when CO{sub 2} uptake was inhibited by COS. Neither CS{sub 2} nor N{sub 2}O acted like COS. It is concluded that COS is an effective and selective inhibitor of active CO{sub 2} transport.

• OSTI ID: 6968377
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 90:3; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
ACID CARBONATES
BIOCHEMICAL REACTION KINETICS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON DIOXIDE FIXATION
CARBON OXIDES
CHALCOGENIDES
CYANOBACTERIA
INHIBITION
KINETICS
MICROORGANISMS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
UPTAKE