2 research outputs found
Revisiting the Role of Xanthophylls in Nonphotochemical Quenching
Photoprotective
nonphotochemical quenching (NPQ) of absorbed solar
energy is vital for survival of photosynthetic organisms, and NPQ
modifications significantly improve plant productivity. However, the
exact NPQ quenching mechanism is obscured by discrepancies between
reported mechanisms, involving xanthophyll–chlorophyll (Xan–Chl)
and Chl–Chl interactions. We present evidence of an experimental
artifact that may explain the discrepancies: strong laser pulses lead
to the formation of a novel electronic species in the major plant
light-harvesting complex (LHCII). This species evolves from a high
excited state of Chl <i>a</i> and is absent with weak laser
pulses. It resembles an excitonically coupled heterodimer of Chl <i>a</i> and lutein (or other Xans at site L1) and acts as a de-excitation
channel. Laser powers, and consequently amounts of artifact, vary
strongly between NPQ studies, thereby explaining contradicting spectral
signatures attributed to NPQ. Our results offer pathways toward unveiling
NPQ mechanisms and highlight the necessity of careful attention to
laser-induced artifacts
Rapid reconstitution of ubiquitinated nucleosome using a non-denatured histone octamer ubiquitylation approach.
BACKGROUND: Histone ubiquitination modification is emerging as a critical epigenetic mechanism involved in a range of biological processes. In vitro reconstitution of ubiquitinated nucleosomes is pivotal for elucidating the influence of histone ubiquitination on chromatin dynamics. RESULTS: In this study, we introduce a Non-Denatured Histone Octamer Ubiquitylation (NDHOU) approach for generating ubiquitin or ubiquitin-like modified histone octamers. The method entails the co-expression and purification of histone octamers, followed by their chemical cross-linking to ubiquitin using 1,3-dibromoacetone. We demonstrate that nucleosomes reconstituted with these octamers display a high degree of homogeneity, rendering them highly compatible with in vitro biochemical assays. These ubiquitinated nucleosomes mimic physiological substrates in function and structure. Additionally, we have extended this method to cross-linking various histone octamers and three types of ubiquitin-like proteins. CONCLUSIONS: Overall, our findings offer an efficient strategy for producing ubiquitinated nucleosomes, advancing biochemical and biophysical studies in the field of chromatin biology