Biosynthesis of a 42-kD Polypeptide in the Cytoplasmic Membrane of the Cyanobacterium Anacystis nidulans Strain R2 during Adaptation to Low CO₂ Concentration

Abstract

When cells of Anacystis nidulans strain R2 grown under high CO2 conditions (3%) were transferred to low CO2 conditions (0.05%), their ability to accumulate inorganic carbon (C1) increased up to 8 times.Cytoplasmic membranes (plasmalemma) isolated at various stages of low CO2 adaptation were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There was a marked increase of a 42-kilodalton polypeptide in the cytoplasmic membrane during adaptation; a linear relationship existed between the amount of this polypeptide and the Cr accumulating capability of the cells. No significant changes were observed during this process in the amount of other polypeptides in the cytoplasmic membranes or in the polypeptide profiles of the thylakoid membranes, cell walls, and soluble fractions. Spectinomycin, an inhibitor of protein biosynthesis, inhibited both the increase of the 42-kilodalton polypeptide and the induction of high Ci-accumulating capability. The incorporation of 135SIsulfate into membrane proteins was greatly reduced during low CO2 adaptation. Radioautograms of the 35S-labeled membrane proteins revealed that synthesis of the 42-kilodalton polypeptide in the cytoplasmic membrane was specifically activated during the adaptation, while that of most other proteins was greatly suppressed. These results suggested that the 42-kilodalton polypeptide in the cytoplasmic membrane is involved in the active Ci transport by A. nidulans strain R2 and its synthesis under low CO2 conditions leads to high Cr-transporting activity. mechanism of Ci transport.Exposure of high C02-grown cells ofcyanobacteria to low CO2 conditions increases their Ci-accumulating capability and their photosynthetic affinity to C1 (15,25,28 Cyanobacteria have a mechanism to transport exogenous Cj2 and concentrate it internally (1,7,13,16,20,27). The C02-concentrating mechanism involves an active C, transport, which is driven by PSI reaction of photosynthesis (20)(21)(22). While the presently available evidence does not allow one to explain the transport with a specific mechanism, three models are most commonly discussed: (a) a primary electrogenic HCO3 pump (9), (b) (29) under aeration with 3% CO2 in air. Continuous illumination was provided by fluorescent lamps at 120 ,umol PAR/M2 -s. For low CO2 adaptation experiments, cells were harvested by centrifugation at 2200g for 10 min, resuspended in fresh BG-11 growth medium supplemented with 20 mM Hepes-NaOH buffer (pH 7.0), and aerated with air containing about 0.05% CO2 under the same light conditions. Gas Exchange Measurements. Cells were harvested by centrifugation at 3000g for 5 min, resuspended in 30 ml of 40 mM Hepes-NaOH buffer (pH 7.0 OMATA AND OGAWA 2* s); the postillumination CO2 burst was measured in the presence of 3 mm iodoacetamide which inhibits photosynthetic CO2 fixation completely (3,21). It has been shown that the amount of intracellular Ci calculated by the CO2 burst method agrees with that measured using the silicone oil-centrifugation method (23). The intrace...

Ethoxyzolamide Inhibition of CO2 Uptake in the Cyanobacterium Synechococcus PCC7942 without Apparent Inhibition of Internal Carbonic Anhydrase Activity

“…This conversion is depicted as occuring largely within or close to the membrane and would be tightly coupled to both the C, pump and a proton efflux mechanism. The identity of the front-end mechanism is unknown, but it is possible that it may involve the 42 kD polypeptide which is induced under low C, conditions and is associated with the cytoplasmic membrane (18 HCOi as compared to CO2 as a substrate (14). Further experiments are necessary to confirm the various elements of this model.…”

A putative HCO−3 transporter in the cyanobacterium Synechococcus sp. strain PCC 79421

“…Sequence similarity between cmpA, encoding a 42-kDa polypeptide which accumulates in the cytoplasmic-membrane of low-CO P -exposed Synechococcus PCC 7942 [28], and nrtA involved in nitrate transport [29], raised the possibility that CmpA may be the periplasmic part of an ABC-type transporter engaged in rgy 3 3 transport ( [21], Omata, personal communication). The role of the 42-kDa polypeptide, however, is not clear since inactivation of cmpA did not a¡ect the ability of Synechococcus PCC 7942 [30] and Synechocystis PCC 6803 [21] to grow under air level of CO P but lowered growth under 20 ppm CO P in air [21].…”

A Mutant of Synechococcus PCC7942 Incapable of Adapting to Low CO2 Concentration

“…A 42-kD polypeptide is synthesized in the cytoplasmic membrane of Synechococcus PCC7942 or PCC6301 during the adaptation process (8,11,12,14 …”

“…A 42-kD polypeptide is synthesized in the cytoplasmic membrane of Synechococcus PCC7942 or PCC6301 during the adaptation process (8,11,12,14). The antibody against this polypeptide cross-reacted with a 45-kD polypeptide in the cytoplasmic membrane of low C02-grown cells of Synechocystis PCC6803 (13 Figure 3.…”