Apoprotein heterogeneity increases spectral disorder and a step-wise modification of the B850 fluorescence peak
Cristian Ilioaia1, Tjaart P J Krüger2, Oana Ilioaia3
1Institut des sciences du vivant Frédéric Joliot, Commissariat à l'Energie Atomique et aux énergies alternatives (CEA), 91191 Gif-sur-Yvette, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91191 Gif-sur-Yvette cedex, France; Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan, 1081 HV Amsterdam, The Netherlands.
Abstract:
It has already been established that the quaternary structure of the main light-harvesting complex (LH2) from the photosynthetic bacterium Rhodopseudomonas palustris is a nonameric 'ring' of PucAB heterodimers and under low-light culturing conditions an increased diversity of PucB synthesis occurs. In this work, single molecule fluorescence emission studies show that different classes of LH2 'rings' are present in "low-light" adapted cells and that an unknown chaperon process creates multiple sub-types of 'rings' with more conformational sub-states and configurations. This increase in spectral disorder significantly augments the cross-section for photon absorption and subsequent energy flow to the reaction centre trap when photon availability is a limiting factor. This work highlights yet another variant used by phototrophs to gather energy for cellular development.
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