Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Science. 2011 Jul 22;333(6041):467-70. doi: 10.1126/science.1203903. Epub 2011 Jun 23.
Free-living cells of the social amoebae Dictyostelium discoideum can aggregate and develop into multicellular fruiting bodies in which many die altruistically as they become stalk cells that support the surviving spores. Dictyostelium cells exhibit kin discrimination--a potential defense against cheaters, which sporulate without contributing to the stalk. Kin discrimination depends on strain relatedness, and the polymorphic genes tgrB1 and tgrC1 are potential components of that mechanism. Here, we demonstrate a direct role for these genes in kin discrimination. We show that a matching pair of tgrB1 and tgrC1 alleles is necessary and sufficient for attractive self-recognition, which is mediated by differential cell-cell adhesion. We propose that TgrB1 and TgrC1 proteins mediate this adhesion through direct binding. This system is a genetically tractable ancient model of eukaryotic self-recognition.
自由生活的粘菌细胞可以聚集并发育成多细胞的子实体，在子实体中，许多细胞会作为柄细胞死亡，从而支撑存活的孢子。粘菌细胞表现出亲缘识别——这是一种潜在的防御机制，可以抵御那些不参与柄细胞形成而只产生孢子的骗子。亲缘识别取决于菌株的亲缘关系，多态基因 tgrB1 和 tgrC1 是该机制的潜在组成部分。在这里，我们证明了这些基因在亲缘识别中的直接作用。我们表明，匹配的 tgrB1 和 tgrC1 等位基因对是进行有吸引力的自我识别所必需的，这种识别是由细胞间的差异粘附介导的。我们提出 TgrB1 和 TgrC1 蛋白通过直接结合来介导这种粘附。该系统是一种可遗传的、古老的真核自我识别的模式生物。
