Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain.
Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Sevilla, Spain.
PLoS Genet. 2018 Sep 25;14(9):e1007677. doi: 10.1371/journal.pgen.1007677. eCollection 2018 Sep.
The std locus of Salmonella enterica, an operon acquired by horizontal transfer, encodes fimbriae that permit adhesion to epithelial cells in the large intestine. Expression of the std operon is bistable, yielding a major subpopulation of StdOFF cells (99.7%) and a minor subpopulation of StdON cells (0.3%). In addition to fimbrial proteins, the std operon encodes two proteins, StdE and StdF, that have DNA binding capacity and control transcription of loci involved in flagellar synthesis, chemotaxis, virulence, conjugal transfer, biofilm formation, and other cellular functions. As a consequence of StdEF pleiotropic transcriptional control, StdON and StdOFF subpopulations may differ not only in the presence or absence of Std fimbriae but also in additional phenotypic traits. Separation of StdOFF and StdON lineages by cell sorting confirms the occurrence of lineage-specific features. Formation of StdOFF and StdON lineages may thus be viewed as a rudimentary bacterial differentiation program.
沙门氏菌的 std 基因座是通过水平转移获得的操纵子，编码允许其黏附在大肠上皮细胞的菌毛。std 操纵子的表达呈双稳态，产生主要的 StdOFF 细胞亚群（99.7%）和次要的 StdON 细胞亚群（0.3%）。除了菌毛蛋白，std 操纵子还编码两个具有 DNA 结合能力的蛋白，StdE 和 StdF，它们控制参与鞭毛合成、趋化性、毒力、接合转移、生物膜形成和其他细胞功能的基因座的转录。由于 StdEF 多效性转录控制，StdON 和 StdOFF 亚群不仅在是否存在 std 菌毛方面可能不同，而且在其他表型特征方面也可能不同。通过细胞分选分离 StdOFF 和 StdON 谱系证实了谱系特异性特征的发生。因此，StdOFF 和 StdON 谱系的形成可以被视为一个原始的细菌分化程序。
