Department of Biology and Biochemistry, University of Bath, Bath, Somerset, UK.
Genome Biol Evol. 2009 Sep 2;1:340-9. doi: 10.1093/gbe/evp033.
Theory predicts that, owing to reduced Hill-Robertson interference, genomic regions with high crossing-over rates should experience more efficient selection. In Saccharomyces cerevisiae a negative correlation between the local recombination rate, assayed as meiotic double-strand breaks (DSBs), and the local rate of protein evolution has been considered consistent with such a model. Although DSBs are a prerequisite for crossing-over, they need not result in crossing-over. With recent high-resolution crossover data, we now return to this issue comparing two species of yeast. Strikingly, even allowing for crossover rates, both the rate of premeiotic DSBs and of noncrossover recombination events predict a gene's rate of evolution. This both questions the validity of prior analyses and strongly suggests that any correlation between crossover rates and rates of protein evolution could be owing to slow-evolving genes being prone to DSBs or a direct effect of DSBs on sequence evolution. To ask if classical theory of recombination has any relevance, we determine whether crossover rates predict rates of protein evolution, controlling for noncrossover DSB events, gene ontology (GO) class, gene expression, protein abundance, nucleotide content, and dispensability. We find that genes with high crossing-over rates have low rates of protein evolution after such control, although any correlation is weaker than that previously reported considering meiotic DSBs as a proxy. The data are consistent both with recombination enhancing the efficiency of purifying selection and, independently, with DSBs being associated with low rates of evolution.
理论预测，由于降低了 Hill-Robertson 干扰，高交叉率的基因组区域应该经历更有效的选择。在酿酒酵母中，局部重组率（通过减数分裂双链断裂（DSBs）来衡量）与局部蛋白质进化率之间的负相关关系被认为与这种模型一致。尽管 DSBs 是交叉的前提条件，但它们不一定导致交叉。有了最近的高分辨率交叉数据，我们现在回到这个问题，比较了两种酵母。引人注目的是，即使考虑到交叉率，前减数分裂 DSB 率和非交叉重组事件的速率都可以预测基因的进化速率。这不仅质疑了先前分析的有效性，而且强烈表明，交叉率与蛋白质进化率之间的任何相关性都可能是由于进化缓慢的基因容易发生 DSBs，或者 DSBs 对序列进化有直接影响。为了探讨经典重组理论是否具有相关性，我们确定交叉率是否可以预测蛋白质进化率，同时控制非交叉 DSB 事件、基因本体（GO）类别、基因表达、蛋白质丰度、核苷酸含量和可 dispensability。我们发现，在进行这种控制后，具有高交叉率的基因的蛋白质进化率较低，尽管与以前考虑减数分裂 DSB 作为替代物的报告相比，任何相关性都较弱。这些数据既与重组增强了净化选择的效率一致，也与 DSBs 与低进化率有关。
