PARENT SESSION
Posters P2B Light, redox and metabolic regulation: Light Reactions. Abstracts (444-478)

State transitions and organisation of PCB antenna in Prochlorothrix Hollandica. Sam Benson^*,1, James Duncan¹, James Barber¹, ¹ The Wolfson Laboratories, London, Greater London, United kingdom

ABSTRACT- State transitions are an adaptive mechanism which enables the maximum rate of photosynthesis in a changing light environment. Linear electron transport between PSI and PSII requires that they receive photons at an equal rate. Many aspects of state transitions are now well understood. In higher plants and green algae, state transitions involve the activation of a kinase and a lateral migration of phosphoLHCII from PSII to PSI. However, state transitions are also found in prokaryotic organisms which do not contain LHCII, but have different light harvesting systems. Here we show Prochlorothrix Hollandica, a prochlorophyte with a chlorophyll a/b containing PCB light harvesting system undergoes changes in room temperature fluorescence arising from PSII in response to selective excitation of PSI and PSII that are characteristic of state transitions. We also observed that phosphorylation of a 36kDa polypeptide occurs in response to changing light conditions. Biochemical characterisation of this phosphoprotein indicates that it is a PCB protein. Further analysis of the organisation of the PCB antenna system of Prochlorothrix has been investigated by electron microscopy and single particle analysis.

KEY WORDS: phosphorylation, state transitions, PCB, Light harvesting antenna