Gerdol Marco, Puillandre Nicolas, De Moro Gianluca, Guarnaccia Corrado, Lucafò Marianna, Benincasa Monica, Zlatev Ventislav, Manfrin Chiara, Torboli Valentina, Giulianini Piero Giulio, Sava Gianni, Venier Paola, Pallavicini Alberto
Department of Life Sciences, University of Trieste, Italy.
Muséum National d'Histoire Naturelle, Département Systématique et Evolution, ISyEB Institut (UMR 7205 CNRS/UPMC/MNHN/EPHE), Paris, France.
Genome Biol Evol. 2015 Jul 21;7(8):2203-19. doi: 10.1093/gbe/evv133.
We report the identification of a novel gene family (named MgCRP-I) encoding short secreted cysteine-rich peptides in the Mediterranean mussel Mytilus galloprovincialis. These peptides display a highly conserved pre-pro region and a hypervariable mature peptide comprising six invariant cysteine residues arranged in three intramolecular disulfide bridges. Although their cysteine pattern is similar to cysteines-rich neurotoxic peptides of distantly related protostomes such as cone snails and arachnids, the different organization of the disulfide bridges observed in synthetic peptides and phylogenetic analyses revealed MgCRP-I as a novel protein family. Genome- and transcriptome-wide searches for orthologous sequences in other bivalve species indicated the unique presence of this gene family in Mytilus spp. Like many antimicrobial peptides and neurotoxins, MgCRP-I peptides are produced as pre-propeptides, usually have a net positive charge and likely derive from similar evolutionary mechanisms, that is, gene duplication and positive selection within the mature peptide region; however, synthetic MgCRP-I peptides did not display significant toxicity in cultured mammalian cells, insecticidal, antimicrobial, or antifungal activities. The functional role of MgCRP-I peptides in mussel physiology still remains puzzling.
我们报道了在地中海贻贝（Mytilus galloprovincialis）中鉴定出一个编码短分泌型富含半胱氨酸肽的新基因家族（命名为MgCRP-I）。这些肽具有高度保守的前体-原肽区域和一个高变的成熟肽，该成熟肽包含六个不变的半胱氨酸残基，以三个分子内二硫键排列。尽管它们的半胱氨酸模式与远缘相关原口动物（如芋螺和蜘蛛）的富含半胱氨酸的神经毒性肽相似，但在合成肽中观察到的二硫键不同排列以及系统发育分析表明MgCRP-I是一个新的蛋白质家族。在其他双壳类物种中进行全基因组和转录组范围的直系同源序列搜索表明，这个基因家族仅在贻贝属物种中存在。与许多抗菌肽和神经毒素一样，MgCRP-I肽以前体-前肽形式产生，通常具有净正电荷，并且可能源自相似的进化机制，即成熟肽区域内的基因复制和正选择；然而合成的MgCRP-I肽在培养的哺乳动物细胞中未显示出显著的毒性、杀虫、抗菌或抗真菌活性。MgCRP-I肽在贻贝生理学中的功能作用仍然令人困惑。
