Institute of Marine Research (IIM), CSIC, Eduardo Cabello 6, 36208 Vigo, Spain.
Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy.
Int J Mol Sci. 2021 Mar 22;22(6):3235. doi: 10.3390/ijms22063235.
Mytimycins are cysteine-rich antimicrobial peptides that show antifungal properties. These peptides are part of the immune network that constitutes the defense system of the Mediterranean mussel (). The immune system of mussels has been increasingly studied in the last decade due to its great efficiency, since these molluscs, particularly resistant to adverse conditions and pathogens, are present all over the world, being considered as an invasive species. The recent sequencing of the mussel genome has greatly simplified the genetic study of some of its immune genes. In the present work, we describe a total of 106 different mytimycin variants in 16 individual mussel genomes. The 13 highly supported mytimycin clusters (A-M) identified with phylogenetic inference were found to be subject to the presence/absence variation, a widespread phenomenon in mussels. We also identified a block of conserved residues evolving under purifying selection, which may indicate the "functional core" of the mature peptide, and a conserved set of 10 invariable plus 6 accessory cysteines which constitute a plastic disulfide array. Finally, we extended the taxonomic range of distribution of mytimycins among Mytilida, identifying novel sequences in , , , , , , and .
肌肽是富含半胱氨酸的抗菌肽，具有抗真菌特性。这些肽是构成贻贝（）免疫网络的一部分。由于贻贝具有高效的免疫系统，因此在过去十年中，贻贝的免疫系统越来越受到关注，这些软体动物对不利条件和病原体具有很强的抵抗力，分布于世界各地，被认为是入侵物种。贻贝基因组的最近测序极大地简化了对其一些免疫基因的遗传研究。在本工作中，我们在 16 个个体贻贝基因组中总共描述了 106 种不同的肌肽变体。通过系统发育推断鉴定的 13 个高度支持的肌肽簇（A-M）被发现存在/不存在变异，这是贻贝中广泛存在的现象。我们还鉴定了一个保守残基块，其进化受到纯化选择的影响，这可能表明成熟肽的“功能核心”，以及一个由 10 个不变加 6 个辅助半胱氨酸组成的保守集合，构成了一个可塑的二硫键阵列。最后，我们在贻贝中扩展了肌肽的分类分布范围，在 、 、 、 、 、 和 中鉴定了新的序列。
