4.5 Article

Correlated fluorescence quenching and topographic mapping of Light-Harvesting Complex II within surface-assembled aggregates and lipid bilayers

Journal

BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
Volume 1859, Issue 10, Pages 1075-1085

Publisher

ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbabio.2018.06.011

Keywords

Light harvesting; Photosynthesis; Non-photochemical quenching (NPQ); Time-resolved fluorescence; Atomic force microscopy (AFM); Light-Harvesting Complex II (LHCII)

Funding

  1. Biotechnology and Biological Sciences Research Council (BBSRC UK) [BB/M013723/1]
  2. BBSRC UK [BB/M000265/1]
  3. European Research Council [338895]
  4. Leverhulme Trust
  5. Human Frontiers Science Programme
  6. Photosynthetic Antenna Research Center (PARC), an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC 0001035]
  7. PARC
  8. BBSRC [BB/M000265/1, BB/M013723/1] Funding Source: UKRI

Ask authors/readers for more resources

Light-Harvesting Complex II (LHCII) is a chlorophyll-protein antenna complex that efficiently absorbs solar energy and transfers electronic excited states to photosystems I and II. Under excess light intensity LHCII can adopt a photoprotective state in which excitation energy is safely dissipated as heat, a process known as Non-Photochemical Quenching (NPQ). In vivo NPQ is triggered by combinatorial factors including transmembrane ApH, PsbS protein and LHCII-bound zeaxanthin, leading to dramatically shortened LHCII fluorescence lifetimes. In vitro, LHCII in detergent solution or in proteoliposomes can reversibly adopt an NPQ-like state, via manipulation of detergent/protein ratio, lipid/protein ratio, pH or pressure. Previous spectroscopic investigations revealed changes in exciton dynamics and protein conformation that accompany quenching, however, LHCII-LHCII interactions have not been extensively studied. Here, we correlated fluorescence lifetime imaging microscopy (FLIM) and atomic force microscopy (AFM) of trimeric LHCII adsorbed to mica substrates and manipulated the environment to cause varying degrees of quenching. AFM showed that LHCII self-assembled onto mica forming 2D-aggregates (25-150 nm width). FLIM determined that LHCII in these aggregates were in a quenched state, with much lower fluorescence lifetimes (similar to 0.25 ns) compared to free LHCII in solution (2.2-3.9 ns). LHCII-LHCII interactions were disrupted by thylakoid lipids or phospholipids, leading to intermediate fluorescent lifetimes (0.6-0.9 ns). To our knowledge, this is the first in vitro correlation of nanoscale membrane imaging with LHCII quenching. Our findings suggest that lipids could play a key role in modulating the extent of LHCII-LHCII interactions within the thylakoid membrane and so the propensity for NPQ activation.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.5
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available