Functional distinctness in the exoproteomes of marine Synechococcus

Abstract

SummaryThe exported protein fraction of an organism may reflect its life strategy and, ultimately, the way it is perceived by the outside world. Bioinformatic prediction of the exported pan‐proteome of P rochlorococcus and S ynechococcus lineages demonstrated that (i) this fraction of the encoded proteome had a much higher incidence of lineage‐specific proteins than the cytosolic fraction (57% and 73% homologue incidence respectively) and (ii) exported proteins are largely uncharacterized to date (54%) compared with proteins from the cytosolic fraction (35%). This suggests that the genomic and functional diversity of these organisms lies largely in the diverse pool of novel functions these organisms export to/through their membranes playing a key role in community diversification, e.g. for niche partitioning or evading predation. Experimental exoproteome analysis of marine S ynechococcus showed transport systems for inorganic nutrients, an interesting array of strain‐specific exoproteins involved in mutualistic or hostile interactions (i.e. hemolysins, pilins, adhesins), and exoenzymes with a potential mixotrophic goal (i.e. exoproteases and chitinases). We also show how these organisms can remodel their exoproteome, i.e. by increasing the repertoire of interaction proteins when grown in the presence of a heterotroph or decrease exposure to prey when grown in the dark. Finally, our data indicate that heterotrophic bacteria can feed on the exoproteome of S ynechococcus.

Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas strains reveals novel insights into the phosphorus scavenging capabilities of soil bacteria

“…Removing the cellular fraction prior to protein extraction can help to identify exoproteins that are involved in the interaction of microorganisms with their environment (Christie‐Oleza et al ., 2012, 2015). The majority of exoproteins detected are associated with nutrient acquisition, motility, cell attachment, defence, communication as well as antagonism (Christie‐Oleza et al ., 2012).…”

Metaproteomics of marine viral concentrates reveals key viral populations and abundant periplasmic proteins in the oligotrophic deep chlorophyll maximum of the South China Sea

“…A recent study shows that urea transporters are present in the MVs of marine Prochlorococcus (Biller et al ., ). Urea transporters are differentially expressed in the exoproteomes of Synechococcus under different conditions, including long‐ or short‐term axenic culture, coculture with a heterotrophic bacterium, dark incubation and short‐term infection by cyanophage (Christie‐Oleza et al ., ). These studies suggest that the urea transporter detected in our VCs might be associated with MVs produced from cyanobacteria and involved in nitrogen cycling.…”

“…Proteins involved in other biological processes were also detected, such as stress response, cell motility, translation, carbohydrate metabolism, carbon fixation, amino acid metabolism, replication, recombination and repair, C1 metabolism, energy metabolism and photosynthesis (Fig. B), coincident with the exported proteins linked to diverse biological processes observed in laboratory cultivated cyanobacteria (Christie‐Oleza et al ., ). Proteins related to the oxidation of C1 and methylated compounds such as carbon‐monoxide dehydrogenase and formate dehydrogenase were detected in diverse bacterial groups, including the Chloroflexia, Roseovarius , the SAR324 cluster and an uncultured bacterium (Supporting Information Table S6).…”

100 Days of marine Synechococcus–Ruegeria pomeroyi interaction: A detailed analysis of the exoproteome

“…Synechococcus sp. release considerable amounts of organic matter not only in the form of carbohydrates (Biersmith and Benner, ; Bertlisson et al ., ) but also in the form of protein (Christie‐Oleza et al ., ; ). Here, proteins involved in photosynthesis are among the most abundant categories found in the exoproteome of Synechococcus sp.…”