Apoprotein heterogeneity increases spectral disorder and a step-wise modification of the B850 fluorescence peak position

Biochim Biophys Acta Bioenerg. 2018 Feb;1859(2):137-144. doi: 10.1016/j.bbabio.2017.11.003. Epub 2017 Nov 21.


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.

Keywords: Light harvesting complexes; Photosynthesis; Purple bacteria; Single molecule spectroscopy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoproteins / chemistry*
  • Bacterial Proteins / chemistry*
  • Light-Harvesting Protein Complexes / chemistry*
  • Rhodopseudomonas / chemistry*
  • Spectrometry, Fluorescence


  • Apoproteins
  • Bacterial Proteins
  • Light-Harvesting Protein Complexes