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1.
Heterologous hybridization of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) restores the enzyme activities 总被引:3,自引:0,他引:3
A Incharoensakdi T Takabe T Takabe T Akazawa 《Biochemical and biophysical research communications》1985,126(2):698-704
The catalytic core (A8) and small subunit (B) of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) were isolated from two species of cyanobacteria (Aphanothece halophytica and Synechococcus ACMM 323) as well as from the photosynthetic purple sulfur bacterium, Chromatium vinosum. The subunit B is essential for the activity of all three enzymes. The heterologous hybridization of RuBisCO molecules from the three organisms was attempted and the reconstitution of the catalytically active hybrid was achieved between A8 derived from either Aphanothece or Synechococcus and subunit B from Aphanothece, Synechococcus or Chromatium. However, reconstitution of the enzymically active hybrid between A8 from Chromatium and B subunits from the cyanobacteria could not be achieved. Experiments by using high performance liquid column chromatography also showed the formation of a heterologous hybrid possessing RuBP carboxylase activity. 相似文献
2.
Salt inhibition of RuBP carboxylase activity from Aphanothecehalophytica was caused by Cl-, but not by K+ nor Na+. The intracellularCl- concentration increased about 4-fold from 35 mM to 150 mM,when NaCl concentration in the culture medium was increasedfrom 0.5 M to 2.0 M.
1Permanent address: Department of Biochemistry, Faculty of Science,Chulalongkorn University, Bangkok, Thailand (Received February 12, 1988; Accepted June 1, 1988) 相似文献
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CO(2) Fixation Rate and RuBisCO Content Increase in the Halotolerant Cyanobacterium, Aphanothece halophytica, Grown in High Salinities 下载免费PDF全文
The growth of the halotolerant cyanobacterium Aphanothece halophytica, previously adapted to 0.5 molar NaCl, was optimal when NaCl concentration in culture medium was in the range 0.5 to 1.0 molar. The growth was delayed at either too low or too high salinities with lag time of ca. 0.5 day in 0.25 molar NaCl and ca. 2 days in 2 molar NaCl under the experimental conditions. However, the growth rates at the logarithmic phase were similar in the culture media containing NaCl in the range 0.25 to 2.0 molar. The capacity of photosynthetic CO2 fixation increased 3.7-fold in the cells at the logarithmic phase as NaCl concentration in the culture medium increased from 0.25 to 2.0 molar. The protein level of ribulose 1,5-bisphosphate carboxylase/oxygenase was also found to increase with increasing salinity using both an immunoblotting method and protein A-gold immunoelectron microscopy. These results indicate that high photosynthetic capacity and high ribulose 1,5-bisphosphate carboxylase/oxygenase content may entail an important role in betaine synthesis and adaptation of the A. halophytica cells to high NaCl level. 相似文献
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Promariya Authen Mäenpää Pirkko Incharoensakdi Aran Raksajit Wuttinun 《Journal of applied phycology》2021,33(4):2313-2325
Journal of Applied Phycology - In this study, the dried biomass of Synechocystis sp. PCC 6803 was used as biosorbent for removing Fe(III)) ions from aqueous solution. The effects of exposure time,... 相似文献
6.
Samart Taikhao Suwannee Junyapoon Aran Incharoensakdi Saranya Phunpruch 《Journal of applied phycology》2013,25(2):575-585
The effects of several physiological parameters on H2 production rate in the unicellular halotolerant cyanobacterium Aphanothece halophytica were investigated. Under nitrogen deprivation, the growth of cells was inhibited, but H2 production rate was enhanced approximately fourfold. Interestingly, cells grown under sulfur deprivation exhibited a decrease in cell growth, H2 production rate, and bidirectional hydrogenase activity. Glucose was the preferred sugar source for H2 production by A. halophytica, but H2 production decreased at high glucose concentrations. H2 production rate was optimum when cells were grown in the presence of 0.75 M?NaCl, or 0.4 μM?Fe3+, or 1 μM?Ni2+. The optimum light intensity and temperature for H2 production were 30 μmol photons m?2?s?1 and 35 °C, respectively. A two-stage culture of A. halophytica was performed in order to overcome the reduction of cell growth in N-free medium. In the first stage, cells were grown in normal medium to accumulate biomass, and in the second stage, H2 production by the obtained biomass was induced by growing cells in N-free medium supplemented with various chemicals for 24 h. A. halophytica grown in N-free medium containing various MgSO4 concentrations had a high H2 production rate between 11.432 and 12.767 μmol H2 mg?chlorophyll a (chl a)?1?h?1, a 30-fold increase compared to cells grown in normal medium. The highest rate of 13.804 μmol H2 mg?chl a ?1?h?1 was obtained when the N-free growth medium contained 0.4 μM Fe3+. These results suggested the possibility of using A. halophytica and some other halotolerant cyanobacteria thriving under extreme environmental conditions in the sea as potential sources for H2 production in the future. 相似文献
7.
The uptake of [14C]choline by a suspension of exponential-phase Aphanothece halophytica under various conditions has been studied. Salt stress was found to enhance the uptake of choline. The kinetics of choline transport followed the Michaelis-Menten relationship with apparent K(m) values of 272 and 286 microM, maximum rates of transport (V(max)) of 18 and 37 nmol/min/mg protein for unstressed and salt-stressed cells, respectively. Choline uptake under salt stress was significantly reduced in chloramphenicol-treated cells, suggesting that the activation by salt stress occurred via an inducible transport system. This was corroborated by the existence of the periplasmic choline binding protein, whose content was higher in cells grown under salt-stress condition. Exogenously provided choline significantly increased the growth rate of cells grown under salt stress, although less efficiently than glycine betaine. The presence of 1 mM choline in the growth medium conferred tolerance to high salinity on A. halophytica with the maintenance of high growth up to 1.5 M NaCl. The uptake of choline was Na(+)-dependent, sensitive to various metabolic inhibitors as well as thiol-reactive agents. The results of competition studies suggested that N-methyl on one end of molecule and on the other end either an aldehyde, an alcohol or a neutral group were important features for substrate recognition. 相似文献
8.
We have investigated conditions leading to the degradation of glycinebetaine in Aphanothece halophytica and have shown the activity of betaine-homocysteine methyltransferase (BHMT). The intracellular glycinebetaine level was
decreased approximately 50% after 36 h salt downshock from 2.0 m NaCl medium to 0.5 m NaCl medium. A slight additional decrease
of glycinebetaine occurred when salt downshock was combined with dark treatment. The omission of carbon and nitrogen sources
in the growth medium further decreased intracellular glycinebetaine. The activity of BHMT increased from 0 to 460 nmol h−1mg−1 after 3 h salt downshock. Higher strength of salt downshock resulted in higher activity of the enzyme. Small increase of
the enzyme activity was also observed when A. halophytica was deprived of carbon and nitrogen sources in the growth medium.
Received: 17 March 2000 / Accepted: 24 April 2000 相似文献
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Juntarajumnong W Hirani TA Simpson JM Incharoensakdi A Eaton-Rye JJ 《Archives of microbiology》2007,188(4):389-402
The Pho regulon is controlled by the histidine kinase-response regulator pair SphS–SphR in many cyanobacteria and up-regulation
of the Pho regulon can be monitored by measuring alkaline phosphatase activity. However, the mechanism regulating signal transduction
between SphS and SphR has not been described. We have created a cyanobacterial strain allowing the introduction of mutations
into the transmitter domain of SphS. Mutations at Thr-167, adjacent to the H motif of SphS, introduce elevated alkaline phosphatase
activity in the presence of phosphate and an enhancement of alkaline phosphatase activity, when compared to the control strain,
in phosphate-limiting media. SphU acts as a negative regulator of the SphS–SphR system in Synechocystis sp. PCC 6803 and we show that constitutive alkaline phosphatase activity in the absence of SphU requires signal transduction
through SphS and SphR. However, constitutive activity in the absence of SphU is severely attenuated in the ΔSphU:SphS-T167N
mutant. Our data suggest that Thr-167 contributes to the mechanism underlying regulation by SphU. We have also assembled a
deletion mutant system allowing the introduction of mutations into SphR and show that Gly-225 and Trp-236, which are both
conserved in SphR from cyanobacteria, are essential for activation of the Pho regulon under phosphate-limiting conditions. 相似文献