The Panoptes antiphage system defends bacteria by detecting phage-encoded counter-defences that sequester cyclic nucleotide signals, triggering membrane disruption and highlighting a broader strategy of sensing immune evasion through second-messenger surveillance.

Microbial rhodopsins are photoactive membrane proteins known for transporting small inorganic ions such as H+, Cl–, and Na+. Their compact structure─comprising seven transmembrane helices─has long bee...

Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans...

Carbon dioxide (CO2) assimilation by the enzyme Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) underpins biomass accumulation in photosy...

YouTube video by MBARI (Monterey Bay Aquarium Research Institute)

Thioredoxins are ubiquitous redox proteins that are found in all domains of life. These conserved proteins are also found in many phages, including marine cyanophages that infect the ecologically important marine cyanobacteria. However, their role in phage infection is not known. Cyanophages also carry many small genes lacking homology to known functional domains. Whether these have a functional role or not remains unknown. Here, we explore the distribution and role of a cyanophage thioredoxin (trxA), and that of a small gene directly downstream of it (g26), in phage infection. For this we used the T7-like cyanophage, Syn5, which infects an open-ocean marine Synechococcus strain, WH8109. We found that thioredoxin genes are common in phage genomes, including in cyanophages. The g26 gene, however, is restricted in it distribution to the cyanophages. The cyanophage thioredoxin is catalytically active and it increases phage DNA replication, progeny production and competitive fitness. It also negatively impacts host growth. The g26 gene product is translationally coupled to, and thus dependent on, translation of the thioredoxin gene. This gene itself significantly increases phage virulence and fitness, yet reduces burst size. Our findings demonstrate that cyanophage thioredoxins impact phage fitness and infection physiology and that small viral genes with no homology to known genes can play an important role in the infection process. These findings provide insights into the importance of unusual genes in phage genomes and show that they are likely to play an important role in the interactions between abundant cyanobacteria and cyanophages in ocean ecosystems. ### Competing Interest Statement The authors have declared no competing interest.

Adaptive evolution is key for species to persist in a warming climate. However, how adaptive genetic variants arise and shape both past and future evolutionary trajectories remains largely unknown. In...

Scientists have confirmed that the Atlas blue butterfly carries the most chromosomes of any animal, with 229 pairs. Unlike duplication, its chromosomes split apart, reshaping its genome in surprising ...

Yasuhisa Mizutani marvels at how effectively nature utilizes the π-conjugated system of retinal in proteins.

Accurate protein structure prediction followed by structural homology detection enable the functional annotation of otherwise obscure viral protein-co…

The linear tetrapyrrole-binding cyanobacteriochrome (CBCR) photoreceptors have been extensively analyzed so far and found to be highly diverse in spectral properties. Here, we describe the methods to search novel CBCR molecules from the database, perform...