Lyons Nicholas A, Kraigher Barbara, Stefanic Polonca, Mandic-Mulec Ines, Kolter Roberto
Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia.
Curr Biol. 2016 Mar 21;26(6):733-42. doi: 10.1016/j.cub.2016.01.032. Epub 2016 Feb 25.
Multicellularity inherently involves a number of cooperative behaviors that are potentially susceptible to exploitation but can be protected by mechanisms such as kin discrimination. Discrimination of kin from non-kin has been observed in swarms of the bacterium Bacillus subtilis, but the underlying molecular mechanism has been unknown. We used genetic, transcriptomic, and bioinformatic analyses to uncover kin recognition factors in this organism. Our results identified many molecules involved in cell-surface modification and antimicrobial production and response. These genes varied significantly in expression level and mutation phenotype among B. subtilis strains, suggesting interstrain variation in the exact kin discrimination mechanism used. Genome analyses revealed a substantial diversity of antimicrobial genes present in unique combinations in different strains, with many likely acquired by horizontal gene transfer. The dynamic combinatorial effect derived from this plethora of kin discrimination genes creates a tight relatedness cutoff for cooperation that has likely led to rapid diversification within the species. Our data suggest that genes likely originally selected for competitive purposes also generate preferential interactions among kin, thus stabilizing multicellular lifestyles.
多细胞性本质上涉及许多合作行为，这些行为可能容易受到利用，但可以通过亲属识别等机制来保护。在枯草芽孢杆菌群体中已观察到对亲属和非亲属的区分，但潜在的分子机制尚不清楚。我们使用遗传学、转录组学和生物信息学分析来揭示该生物体中的亲属识别因子。我们的结果确定了许多参与细胞表面修饰以及抗菌物质产生和反应的分子。这些基因在枯草芽孢杆菌菌株之间的表达水平和突变表型有显著差异，表明所使用的精确亲属识别机制存在菌株间差异。基因组分析揭示了不同菌株中以独特组合形式存在的大量抗菌基因的多样性，其中许多可能是通过水平基因转移获得的。这种大量亲属识别基因产生的动态组合效应为合作创造了严格的亲缘关系界限，这可能导致了该物种内的快速分化。我们的数据表明，最初可能为竞争目的而选择的基因也会在亲属之间产生优先相互作用，从而稳定多细胞生活方式。
