Lifestyle evolution in cyanobacterial symbionts of sponges
The "Candidatus Synechococcus spongiarum" group includes different clades of cyanobacteria with high 16S rRNA sequence identity (~99%) and is the most abundant and widespread cyanobacterial symbiont of marine sponges. The first draft genome of a "Ca. Synechococcus spongiarum" group member was recently published, providing evidence of genome reduction by loss of genes involved in several nonessential functions. However, "Ca. Synechococcus spongiarum" includes a variety of clades that may differ widely in genomic repertoire and consequently in physiology and symbiotic function. Here, we present three additional draft genomes of "Ca. Synechococcus spongiarum," each from a different clade. By comparing all four symbiont genomes to those of free-living cyanobacteria, we revealed general adaptations to life inside sponges and specific adaptations of each phylotype. Symbiont genomes shared about half of their total number of coding genes. Common traits of "Ca. Synechococcus spongiarum" members were a high abundance of DNA modification and recombination genes and a reduction in genes involved in inorganic ion transport and metabolism, cell wall biogenesis, and signal transduction mechanisms. Moreover, these symbionts were characterized by a reduced number of antioxidant enzymes and low-weight peptides of photosystem II compared to their free-living relatives. Variability within the "Ca. Synechococcus spongiarum" group was mostly related to immune system features, potential for siderophore-mediated iron transport, and dependency on methionine from external sources. The common absence of genes involved in synthesis of residues, typical of the O antigen of free-living Synechococcus species, suggests a novel mechanism utilized by these symbionts to avoid sponge predation and phage attack.
- Profiling Reactive Metabolites via Chemical Trapping and Targeted Mass Spectrometry
- Does the brain listen to the gut?
- (Meta)genomic insights into the pathogenome of Cellulosimicrobium cellulans
- A robust adaptive denoising framework for real-time artifact removal in scalp EEG measurements
- Imputing Gene Expression in Uncollected Tissues Within and Beyond GTEx
- Small Rad51 and Dmc1 Complexes Often Co-occupy Both Ends of a Meiotic DNA Double Strand Break
- Controlling the Cyanobacterial Clock by Synthetically Rewiring Metabolism
- Choosing experiments to accelerate collective discovery
- The transcriptional landscape of age in human peripheral blood
- Digital signaling decouples activation probability and population heterogeneity