ABC  Vol.3 No.1 , February 2013
Spectral properties of LH2 exhibit very similar even when heterologously express LH2 with β-subunit fusion protein in Rhodobacter sphaeroides

Interactions between the light-harvesting subunits and the non-covalently bound photopigments attribute considerably to the spectral properties of photosynthetic bacteria light-harvesting complexes. In our previous studies, we have constructed a novel Rhodobacter sphaeroides expression system. In the present study, we focus on the spectral properties of LH2 when heterologously express LH2 with β-subunit- GFP fusion protein in Rb. sphaeroides. Near infra-red spectrum of LH2 remained nearly unchanged as measured by spectroscopy. Fluorescence spectrum suggested that the LH2 with β-subunit-GFP fusion protein complexes still possessed normal activity in energy transfer. However, photopigments contents were significantly decreased to a very low level in the LH2 with β-subunit-GFP fusion protein complexes compared to that of LH2. FT-IR spectra indicated that interactions between photopigments and LH2 α/β- subunits appeared not to be changed. It was concluded that the LH2 spectral properties exhibited very similar even when heterologously expressed LH2 b-subunit fusion protein in Rb. sphaeroides. Our present study may supply a new insight into better understand the interactions between light-harvesting subunits and photopigments and bacterial photosynthesis and promote the development of the novel Rb. sphaeroides expression system.

Cite this paper: Zhao, Z. , Nie, X. , Hu, Z. , Chen, G. , Li, Z. and Zhang, Z. (2013) Spectral properties of LH2 exhibit very similar even when heterologously express LH2 with β-subunit fusion protein in Rhodobacter sphaeroides. Advances in Biological Chemistry, 3, 101-107. doi: 10.4236/abc.2013.31013.

[1]   Tucker, J.D., Siebert, C.A., Escalante, M., et al. (2010) Membrane invagination in Rhodobacter sphaeroides is initiated at curved regions of the cytoplasmic membrane, then forms both budded and fully detached spherical vesicles. Molecular Microbiology, 4, 833-847. doi:10.1111/j.1365-2958.2010.07153.x

[2]   Pugh, R.J., McGlynn, P., Jones, M.R., et al. (1998) The LH1-RC core complex of Rhodobacter sphaeroides: Interaction between components, time-dependent assembly, and topology of the PufX protein. Biochimica et Bio physica Acta, 3, 301-316.

[3]   Olsen, J.D., Tucker, J.D., Timney, J.A., et al. (2008) The organization of LH2 complexes in membranes from Rhodobacter sphaeroides. Journal of Biological Chemis try, 45, 30772-30779. doi:10.1074/jbc.M804824200

[4]   Zeilstra-Ryalls, J., Gomelsky, M., Eraso, J.M., et al. (1998) Control of photosystem formation in Rhodobacter sphaeroides. Journal of Bacteriology, 11, 2801-2809.

[5]   Boonstra, A.F., Visschers, R.W., Calkoen, F., et al. (1993) Structural characterization of the B800-850 and B875 light-harvesting antenna complexes from Rhodobacter sphaeroides by electron microscopy. Biochimica et Biophysica Acta, 50, 181-188.

[6]   Hu, X., Damjanovic, A., Ritz, T., et al. (1998) Architecture and mechanism of the light-harvesting apparatus of purple bacteria. Proceedings of the National Academy of Sciences of the USA, 11, 5935-5941. doi:10.1073/pnas.95.11.5935

[7]   Walz, T., Jamieson, S.J., Bowers, C.M., et al. (1998) Projection structures of three photosynthetic complexes from Rhodobacter sphaeroides: LH2 at 6 ?, LH1 and RC-LH1 at 25 A. Journal of Molecular Biology, 4, 833-845. doi:10.1006/jmbi.1998.2050

[8]   Lang, H.P. and Hunter, C.N. (1994) The relationship between carotenoid biosynthesis and the assembly of the light-harvesting LH2 complex in Rhodobacter sphaeroides. Biochemical Journal, 298, 197-205.

[9]   McDermott, G., Prince, S.M., Freer, A.A., et al. (1995) Crystal structure of an integral membrane light-harves ting complex from photosynthetic bacteria. Nature, 374, 517-521. doi:10.1038/374517a0

[10]   Braun, P., Gebhardt, R., Kwa, L., et al. (2005) High pressure near infrared study of the mutated light-har vesting complex LH2. Brazilian Journal of Medical and Biological Research, 8, 1273-1278.

[11]   Law, C.J., Roszak, A.W., Southall, J., et al. (2004) The structure and function of bacterial light-harvesting complexes. Molecular Membrane Biology, 3, 183-191. doi:10.1080/09687680410001697224

[12]   Urboniene, V., Vrublevskaja, O., Trinkunas, G., et al. (2007) Solvation effect of bacteriochlorophyll excitons in light-harvesting complex LH2. Biophysical Journal, 6, 2188-2198. doi:10.1529/biophysj.106.103093

[13]   Pandit, A., Buda, F., van Gammeren, A.J., et al. (2010) Selective chemical shift assignment of bacteriochloro phyll a in uniformly [13C-15N]-labeled light-harvesting 1 complexes by solid-state NMR in ultrahigh magnetic field. Journal of Physical Chemistry B, 18, 6207-6215. doi:10.1021/jp100688u

[14]   Fowler, G.J., Sockalingum, G.D., Robert, B., et al. (1994) Blue shifts in bacteriochlorophyll absorbance correlate with changed hydrogen bonding patterns in light-harvesting 2 mutants of Rhodobacter sphaeroides with al terations at alpha-Tyr-44 and alpha-Tyr-45. Biophysical Journal, 299, 695-700.

[15]   Gall, A., Fowler, G.J., Hunter, C.N., et al. (1997) Influ ence of the protein binding site on the absorption proper ties of the monomeric bacteriochlorophyll in Rhodobacter sphaeroides LH2 complex. Biochemistry, 51, 16282 16287. doi:10.1021/bi9717237

[16]   Braun, P., Vegh, A.P., von Jan, M., et al. (2003) Identifi cation of intramembrane hydrogen bonding between 13(1) ketogroup of bacteriochlorophyll and serine residue alpha27 in the LH2 light-harvesting complex. Biochim Biophys Acta, 1, 19-26.

[17]   Garcia-Martin, A., Kwa, L.G., Strohmann, B., et al. (2006) Structural role of (bacterio)chlorophyll ligated in the energetically unfavorable beta-position. Journal of Biological Chemistry, 15, 10626-10634. doi:10.1074/jbc.M510731200

[18]   Kwa, L.G., Garcia-Martin, A., Vegh, A.P., et al. (2004) Hydrogen bonding in a model bacteriochlorophyll-binding site drives assembly of light harvesting complex. Journal of Biological Chemistry, 15, 15067-15075. doi:10.1074/jbc.M312429200

[19]   Olsen, J.D., Sockalingum, G.D., Robert, B., et al. (1994) Modification of a hydrogen bond to a bacteriochlorophyll a molecule in the light-harvesting 1 antenna of Rhodo bacter sphaeroides. Proceedings of the National Academy of Sciences of the USA, 15, 7124-7128. doi:10.1073/pnas.91.15.7124

[20]   Kimura, Y., Hirano, Y., Yu, L.J., et al. (2008) Calcium ions are involved in the unusual red shift of the light harvesting 1 Qy transition of the core complex in thermophilic purple sulfur bacterium Thermochromatium tepidum. Journal of Biological Chemistry, 20, 13867 13873. doi:10.1074/jbc.M800256200

[21]   Allen, J.P., Artz, K., Lin, X., et al. (1996) Effects of hydrogen bonding to a bacteriochlorophyll-bacteriopheo phytin dimer in reaction centers from Rhodobacter spha eroides. Biochemistry, 21, 6612-6619. doi:10.1021/bi9528311

[22]   Gall, A., Cogdell, R.J. and Robert, B. (2003) Influence of carotenoid molecules on the structure of the bacterio chlorophyll binding site in peripheral light-harvesting proteins from Rhodobacter sphaeroides. Biochemistry, 23, 7252-7258. doi:10.1021/bi0268293

[23]   Sundstrom, V. and Pullerits, T. (1999) Photosynthetic light-harvesting: Reconciling dynamics and structure of purple bacterial LH2 reveals function of photosynthetic unit. The Journal of Physical Chemistry, 13, 2327-2346. doi:10.1021/jp983722+

[24]   Wormit, M., Harbach, P.H., Mewes, J.M., et al. (2009) Excitation energy transfer and carotenoid radical cation formation in light harvesting complexes—A theoretical perspective. Biochimica et Biophysica Acta, 6, 738-746.

[25]   Moskalenko, A.A., Makhneva, Z.K., Fiedor, L., et al. (2005) Effects of carotenoid inhibition on the photosyn thetic RC-LH1 complex in purple sulphur bacterium Thiorhodospira sibirica. Photosynthesis Research, 1-2, 71 80. doi:10.1007/s11120-005-4473-9

[26]   Garcia-Martin, A., Pazur, A., Wilhelm, B., et al. (2008) The role of aromatic phenylalanine residues in binding carotenoid to light-harvesting model and wild-type com plexes. Journal of Molecular Biology, 1, 154-166. doi:10.1016/j.jmb.2008.07.002

[27]   Hu, Z., Zhao, Z., Pan, Y., et al. (2010) A powerful hybrid pucoperon promoter tightly regulated by both IPTG and low oxygen level. Biochemistry, 4, 519-512.

[28]   Zhao, Z., Hu, Z., Liang, Y., et al. (2010) One-step purifi cation of functional light-harvesting 2 complex from Rhodobacter sphaeroides. Protein & Peptide Letters, 4, 444-448. doi:10.2174/092986610790963663

[29]   Zhao, Z., Hu, Z., Nie, X., et al. (2011) A novel Rhodo bacter sphaeroides expression system for real-time eva luation of heterologous protein expression levels. Protein & Peptide Letters, 6, 568-572. doi:10.2174/092986611795222722

[30]   Hunter, C.N. and Turner, G. (1988) Transfer of genes coding for apoproteins of reaction center and light-har vesting LH1 complexes to Rhodobacter sphearoides. Journal of General Microbiology, 6, 1471-1480.

[31]   Clayton, R.K. and Clayton, B.J. (1981) B850 pigment protein complex of Rhodopseudomonas sphaeroides: Ex tinction coefficients, circular dichroism, and the reverseble binding of bacteriochlorophyll. Proceedings of the National Academy of Sciences of the USA, 9, 5583-5587. doi:10.1073/pnas.78.9.5583

[32]   Bailey, S. and Grossman, A. (2008) Photoprotection in cyanobacteria: Regulation of light harvesting. Photoche mistry and Photobiology, 6, 1410-1420. doi:10.1111/j.1751-1097.2008.00453.x

[33]   DeGrado, W.F., Gratkowski, H. and Lear, J.D. (2003) How do helix-helix interactions help determine the folds of membrane proteins? Perspectives from the study of homo-oligomeric helical bundles. Protein Science, 4, 647 665. doi:10.1110/ps.0236503

[34]   Uyeda, G., Williams, J.C., Roman, M., et al. (2010) The influence of hydrogen bonds on the electronic structure of light-harvesting complexes from photosynthetic bacteria. Biochemistry, 6, 1146-1159. doi:10.1021/bi901247h

[35]   Gratkowski, H., Lear, J.D. and DeGrado, W.F. (2001) Polar side chains drive the association of model trans membrane peptides. Proceedings of the National Academy of Sciences of the USA, 3, 880-885. doi:10.1073/pnas.98.3.880