Thermostability and Ca2+ binding properties of wild type and heterologously expressed PsbO protein from cyanobacterial photosystem II

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Item Type:	Article
Title:	Thermostability and Ca2+ binding properties of wild type and heterologously expressed PsbO protein from cyanobacterial photosystem II
Creators Name:	Loll, B., Gerold, G., Slowik, D., Voelter, W., Jung, C., Saenger, W. and Irrgang, K.D.
Abstract:	Oxygenic photosynthesis takes place in the thylakoid membrane of cyanobacteria, algae, and higher plants. Initially light is absorbed by an oligomeric pigment-protein complex designated as photosystem II (PSII), which catalyzes light-induced water cleavage under release of molecular oxygen for the biosphere on our planet. The membrane-extrinsic manganese stabilizing protein (PsbO) is associated on the lumenal side of the thylakoids close to the redox-active (Mn)4Ca cluster at the catalytically active site of PSII. Recombinant PsbO from the thermophilic cyanobacterium Thermosynechococcus elongatus was expressed in Escherichia coli and spectroscopically characterized. The secondary structure of recombinant PsbO (recPsbO) was analyzed in the absence and presence of Ca2+ using Fourier transform infrared spectroscopy (FTIR) and circular dichroism spectropolarimetry (CD). No significant structural changes could be observed when the PSII subunit was titrated with Ca2+ in vitro. These findings are compared with data for spinach PsbO. Our results are discussed in the light of the recent 3D-structural analysis of the oxygen-evolving PSII and structural/thermodynamic differences between the two homologous proteins from thermophilic cyanobacteria and plants.
Keywords:	Bacterial Proteins, Calcium, Calcium-Binding Proteins, Circular Dichroism, Cyanobacteria, Deuterium Exchange Measurement, Fourier Transform Infrared Spectroscopy, Heat, Photosystem II Protein Complex, Protein Denaturation, Protein Subunits, Recombinant Proteins, Secondary Protein Structure, Spinacia oleracea
Source:	Biochemistry
ISSN:	0006-2960
Publisher:	American Chemical Society
Volume:	44
Number:	12
Page Range:	4691-4698
Date:	1 January 2005
Official Publication:	https://doi.org/10.1021/bi047614r
PubMed:	View item in PubMed

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