FEBS Letters最新文献

In plants and algae, photosynthesis is driven by the absorption of sunlight energy by networks of pigments housed within light-harvesting proteins. Special photosynthetic complexes can intercept the low-energy photons corresponding to the far-red spectrum of the photosynthetically active radiation. These so-called red chlorophyll forms are found in multiple lineages of the Viridiplantae clade, are formed upon a change in spatial organization of chromophores within specific subunits of the photosystem I supercomplex, and can be detected by their unique red-shifted fluorescence emission signatures. Red forms enabled phototrophs to colonize light-limited ecological niches, especially where far-red radiation is enriched by leaf shading. The protein environment plays a key role in determining the occurrence of red forms, promoting strong excitonic interactions among chlorophyll a molecules and facilitating their excitation by low-energy photons. In this review, we present a comprehensive account of the evolutionary diversity of long-wavelength-driven photosynthesis in eukaryotes, and detail the biophysical and structural determinants of this phenomenon. Finally, we discuss how this knowledge can be applied in biotechnology to engineer crop canopies with broadened light absorption and higher yield potential.

Colorectal cancer (CRC) presents significant therapeutic challenges, particularly due to the development of resistance to standard chemotherapeutic agents such as irinotecan. In this study, we aimed to investigate the molecular and phenotypic mechanisms underlying irinotecan resistance in CRC using the LIM1215 cell line model. Transcriptomic analysis demonstrated that drug withdrawal induced major transcriptional reprogramming, characterized by downregulation of ABC transporters (ABCB1 and ABCG2), extracellular matrix-related genes, and markers of epithelial-to-mesenchymal transition (EMT), alongside reactivation of cell cycle pathways. Drug screening further indicated that resistant cells maintained under irinotecan pressure exhibited a multidrug-resistant phenotype, while withdrawn cells regained sensitivity, particularly to tyrosine kinase inhibitors. Supplementation with the efflux inhibitor Elacridar partially restored drug sensitivity in resistant cells, emphasizing the role of transporter-mediated efflux in maintaining resistance.

Lentiviral vectors are powerful tools for long-term expression of large genes in the mammalian brain, but the palette of lentiviral tools available for targeting specific cell subpopulations is restricted. We describe a lentiviral vector for neuronal subtype-specific expression in Cre mouse lines. Combining a Cre-dependent flip excision switch with a GFP and a 2A self-cleaving peptide, it enables identification of living neurons expressing a gene of interest using fluorescence. We validated this vector by targeting neocortical interneuron types and midbrain dopaminergic neurons. Gene expression occurred exclusively in Cre-expressing neurons without altering their basic electrophysiological properties. This system has been designed to be flexible and easy to modify in order to target expression of any gene of interest in any cell subtype.

Rising atmospheric CO₂ negatively affects plant iron (Fe) content, yet the underlying mechanisms remain poorly understood. Here, we identified More Iron under elevated CO₂ (MIC) as a new player involved in Fe homeostasis under elevated CO₂ in Arabidopsis thaliana. MIC is a previously uncharacterized transmembrane protein which we found predominantly localized to the Golgi apparatus. Loss of MIC function results in increased Fe content under elevated CO₂, effectively mitigating the Fe decline observed in plants. MIC protein abundance is reduced in roots under elevated CO₂, suggesting post-transcriptional regulation of protein stability. This work identifies MIC as a novel component in the plant response to elevated CO₂, with potential implications for improving the nutritional quality of crops under climate change.

DNA copy number changes are the most frequent genomic alterations in cancer cells. Here, we demonstrate that Rad27/FEN1, a structure-specific nuclease in budding yeast, plays a crucial role in maintaining the stability of the ribosomal DNA (rDNA) repeats. Severe rDNA instability is observed in the rad27∆ mutant, independently of Fob1-mediated DNA replication fork arrest and DNA double-strand break (DSB) formation in the rDNA. The rad27Δ mutant accumulates Okazaki fragments in the rDNA region, without inducing the formation of detectable DSBs. Similar rDNA instability is observed in DNA ligase^Cdc9-deficient cells. Furthermore, Exonuclease 1 and PCNA partially compensate for the loss of Rad27 in rDNA stabilization. These findings highlight the importance of proper Okazaki fragment maturation in the maintenance of rDNA stability.

Most mitochondrial proteins are synthesized in the cytosol and imported into the organelle. Here, we describe a novel Import and de-Quenching Competition (IQ-compete) assay which monitors the import efficiency of model proteins by fluorescence in living cells. For this method, the sequence of the tobacco etch virus (TEV) protease is fused to a mitochondrial precursor and coexpressed with a cytosolic reporter which becomes fluorescent upon TEV cleavage. Thus, inefficient import of the fusion protein leads to a fluorescent signal. With the IQ-compete assay, the import efficiency of proteins can be reliably analyzed in fluorescence readers, by flow cytometry, by microscopy, and by western blotting. We are convinced that the IQ-compete assay will be a powerful strategy for many different applications.

CRISPR-Cas systems provide adaptive immunity to bacteria by recognizing and destroying foreign genetic elements. The type I-E CRISPR-Cas system utilizes a multi-subunit Cascade complex to detect target DNA and recruit the Cas3 nuclease for degradation. To overcome this defense, bacteriophages have evolved anti-CRISPR (Acr) proteins that inhibit various steps of the CRISPR interference pathway. Here, we determined the crystal structure of AcrIE8.1, an uncharacterized Acr, revealing it binds to Cas11, a Cascade subunit, to disrupt function. AcrIE8.1 has a compact fold with a defined Cas11-binding interface, suggesting a unique inhibitory mechanism among AcrIE proteins. These findings highlight Cas11 as a critical target for Acr-mediated immune evasion.

To mark the 10th anniversary of International Day of Women and Girls in Science on 11th February 2025, FEBS Letters opened a writing contest on the topic of female role models in science. We invited entrants not only to reflect on the careers of prominent academics, but also to share stories about the supervisors, colleagues, and other women who have inspired their own research journeys. Here, we present one of two runners-up, an essay by physicist Cara Giovanetti (UC Berkeley and Lawrence Berkeley National Lab), which maps out the challenges faced by women in physical science in an antagonistic political climate through conversations with mentors and colleagues.