Changes in Relative Thylakoid Protein Abundance Induced by Fluctuating Light in the Diatom Thalassiosira pseudonana

One of the hallmarks
of marine diatom biology is their ability
to cope with rapid changes in light availability due to mixing of
the water column and the lens effect. We investigated how irradiance
fluctuations influence the relative abundance of key photosynthetic
proteins in the centric diatom Thalassiosira pseudonana by means of mass-spectrometry-based approaches for relative protein
quantitation. Most notably, fluctuating-light conditions lead to a
substantial overall up-regulation of light-harvesting complex proteins
as well as several subunits of photosystems II and I. Despite an initial
delay in growth under FL, there were no indications of FL-induced
photosynthesis limitation, in contrast to other photosynthetic organisms.
Our findings further strengthen the notion that diatoms use a qualitatively
different mechanism of photosynthetic regulation in which chloroplast–mitochondria
interaction has overtaken crucial regulatory processes of photosynthetic
light reactions that are typical for the survival of land plants,
green algae, and cyanobacteria.