A proteomics study on establishment and functionality of chimeric protein complexes in hybrid yeast species and their effect on reproductive isolation

属于不同物种的生物通常不能相互交配。然而，在自然界中，如果两个物种的亲缘关系足够近，它们有时可以繁殖产生可存活的，尽管不育的杂交种。这种情况的一个常见例子是“骡子”，一个公驴和一个母马的杂交，这是可行的，但不育。该项目旨在研究杂交物种中发生的蛋白质相互作用，并着手了解这种杂交物种中存在的两种遗传信息是否作为单独的单位发挥作用，或者它们之间是否存在自然的相互作用。如果这两组亲本蛋白质确实相互作用，我们想量化这种交流在适应性和杂交适应性方面的影响（即，骡子的特征性愚蠢和坏脾气是由于马和驴的蛋白质组之间复杂的相互作用吗？是不是因为这种相互作用，骡子比它们的父母更健康、更有活力？）我建议使用酵母属的酵母物种的杂交种来解决这个问题，酵母属是真菌世界的骡子。S. cerevisiae，S. paradoxus，S. mikeland和S. bayanus可以交配，产生的杂交细胞虽然能够通过出芽分裂，但不能产生活的芽细胞，也称为孢子。所有这些物种的完整遗传蓝图及其遗传多样性的可用性为科学家研究分子进化和在这些生物中建立遗传隔离屏障提供了一个很好的机会。在这个时候，没有实验研究看蛋白质网络的相互作用及其对物种之间的杂种适应性的影响是可用的。我们建议看看蛋白质复合物的建立，在杂交酵母细胞中参与不同的细胞功能。将分子标签连接到表达所选复合物的亚基A的基因上。然后可以使用生物化学和化学策略分离和注释具有所有相互作用伴侣的标记亚基。所鉴定的相互作用蛋白质可以全部属于一个亲本物种（其中基因已被标记的物种），或者属于两种亲本类型。因此，这种方法将告诉我们蛋白质复合物的成员是否能够与来自两种酵母亲本物种的伴侣自然相互作用。我们还建议强制装配嵌合蛋白复合物在酵母杂交。这将使我们能够研究所得杂交体在贫营养和富营养条件下的适应性，并评估同源蛋白质的不同程度的互补能力（即，在杂交1，2细胞中，物种1的蛋白质A是否能够在功能上取代来自物种2的蛋白质A '？）。该项目代表了第一次尝试调查同源蛋白质的连接，来自两个物种，同时存在于杂交细胞中，以及它们对两个物种的适应性和交配后障碍的影响。

Organisms belonging to different species usually cannot mate with each other. However, in nature, if two species are sufficiently closely related, they can sometimes breed producing viable, although infertile, hybrids. A common place example of this condition is the 'mule', a cross of a male donkey and a female horse, which is viable but sterile. This Project aims to study the protein interactions which occur in hybrid species, and sets out to understand whether the two genetic information present in such hybrids acts and function as separate units or if there is a natural interaction between them. If the two set of parental proteins indeed cross-talk, we would like to quantify the effect of such communication in term of adaptation and fitness of the hybrid (i.e. Are the characteristic mule's stubbornness and bad-temper due to complex interactions between the horse's and donkey's proteomes? Is it because of such interactions that mules are fitter and more vigorous than their parents?). I propose to tackle this problem using hybrids of yeast species belonging to the genus Saccharomyces, the mules of the fungal world. S. cerevisiae, S. paradoxus, S. mikatae and S. bayanus can mate and the resulting hybrid cells, although abler to divide by budding, are unable to produce viable germs cells, also called spores. The availability of the complete genetic blueprint for all these species and their genetic versatility provide a great opportunity for the scientist to study molecular evolution and the establishment of genetic isolation barriers in these organisms. At this time no experimental studies looking at the protein network interaction and its effect on fitness in hybrids between species is available. We propose to look at the establishment of protein complexes, involved in different cell functions in hybrid yeast cell. A molecular tag will be attached to genes expressing the subunit A of the chosen complexes. The tagged subunit with all the interacting partners can then be isolated and annotated using biochemical and chemical strategies. The interacting proteins identified could either all belong to one parental species (the one in which the gene has been tagged), or to both parental types. So, this approach will tell us whether members of protein complexes, are able to interact naturally with the partners derived from both yeast parental species. We also propose to force the assembly of chimeric protein complexes in yeast hybrids. This will allow us to study the fitness of the resulting hybrids in poor and rich nutrition conditions, and to assess the different degree of complementation ability of the homologous protein (i.e. is protein A of species 1 able to functionally substitute protein A' from species 2 in the hybrid 1,2 cell?). This project represents the first attempt to investigate the connections of homologous proteins, deriving from two species, that are present simultaneously in the hybrid cell, and their impact on fitness and post-mating barriers of the two species considered.