Institute of Life Science, Swansea University Medical School, United Kingdom.
Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy.
Genome Biol Evol. 2017 Dec 1;9(12):3265-3281. doi: 10.1093/gbe/evx235.
Many bivalve species have two types of mitochondrial DNA passed independently through the female line (F genome) and male line (M genome). Here we study the cytochrome oxidase I protein in such bivalve species and provide evidence for differences between the F and M proteins in amino acid property values, particularly relating to hydrophobicity and helicity. The magnitude of these differences varies between different regions of the protein and the change from the ancestor is most marked in the M protein. The observed changes occur in parallel and in the same direction in the different species studied. Two possible causes are considered, first relaxation of purifying selection with drift and second positive selection. These may operate in different ways in different regions of the protein. Many different amino acid substitutions contribute in a small way to the observed variation, but substitutions involving alanine and serine have a quantitatively large effect. Some of these substitutions are potential targets for phosphorylation and some are close to residues of functional importance in the catalytic mechanism. We propose that the observed changes in the F and M proteins might contribute to functional differences between them relating to ATP production and mitochondrial membrane potential with implications for sperm function.
许多双壳类物种有两种类型的线粒体 DNA，分别通过母系（F 基因组）和父系（M 基因组）独立传递。在这里，我们研究了此类双壳类物种中的细胞色素氧化酶 I 蛋白，并提供了 F 蛋白和 M 蛋白在氨基酸性质值方面存在差异的证据，特别是在疏水性和螺旋性方面。这些差异的大小在蛋白质的不同区域之间有所不同，而且 M 蛋白中从祖先开始的变化最为显著。在研究的不同物种中，观察到的变化以相同的方向平行发生。考虑了两种可能的原因，首先是随着漂移放松了净化选择，其次是正选择。这些可能在蛋白质的不同区域以不同的方式起作用。许多不同的氨基酸取代以较小的方式导致了观察到的变异，但涉及丙氨酸和丝氨酸的取代具有定量上的大影响。这些取代中的一些是磷酸化的潜在靶点，一些靠近催化机制中功能重要的残基。我们提出，F 和 M 蛋白中观察到的变化可能有助于它们之间与 ATP 产生和线粒体膜电位相关的功能差异，这对精子功能有影响。
