Induced changes in the proteomic profile of the phaeophyte Saccharina japonica upon colonization by the bryozoan Membranipora membranacea

The lacy crust bryozoan Membranipora membranacea frequently colonizes the late harvested blades of aquacultured Saccharina japonica. From proteomic profiles of S. japonica, 145 and 91 protein spots were detected from colonized and healthy tissues, respectively. Among them, 69 and 32 spots were significantly up- and downregulated, respectively, in expression level upon colonization. In M. membranacea colonized tissue, tripartite motif protein 2-like, microcompartments protein, carboxysome peptide shell peptide, trypsin precursor-like, transmembrane protein, two-component response regulator PilR, spermine/spermidine synthase, vanadium-dependent bromoperoxidase, peptide chain release factor 1, interaptin, 50S ribosomal protein L1P, plus agglutinin and leucine-rich repeat protein were upregulated, whereas protoporphyrinogen oxidase, PIH1 domain-containing protein 2, GTPase-activating protein alpha, cytoplasmic threonyl-tRNA synthetase, flavanone 3-hydroxylase, and eukaryotic translation initiation factor 3 proteins were downregulated. Moreover, DEAD/DEAH box helicase, glutamyl-tRNA reductase, and chaperone DnaJ protein were newly expressed in the colonized tissue. Most of the up- and downregulated proteins are known to be related to stress control, defense mechanisms, signal transduction, photosynthesis, protein metabolism, and the cytoskeleton.