Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Spain.
Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, Spain.
Microbiol Spectr. 2022 Aug 31;10(4):e0045422. doi: 10.1128/spectrum.00454-22. Epub 2022 Jun 29.
Gene duplications significantly impact the gene repertoires of both eukaryotic and prokaryotic microorganisms. The genomes of pathogenic Escherichia coli strains share a group of duplicated genes whose function is mostly unknown. The gene is one of the duplicates encoded in several pathogenic E. coli strains. The function of its gene product was investigated in the uropathogenic E. coli strain CFT073, which contains a single functional copy. The IrmA protein structure mimics that of human interleukin receptors and likely plays a role during infection. The enteroaggregative E. coli strain 042 contains two functional copies of the gene. In the present work, we investigated their biological roles. The _ allele is expressed under several growth conditions. Its expression is modulated by the global regulators OxyR and Hha, with optimal expression at 37°C and under nutritional stress conditions. Expression of the allele can only be detected when the allele is knocked out. Differences in the promoter regions of both alleles account for their differential expression. Our results show that under several environmental conditions, the expression of the IrmA protein in strain 042 is dictated by the _4509 allele. The _2244 allele appears to play a backup role to ensure IrmA expression when the _4509 allele loses its function. Gene duplications occur in prokaryotic genomes at a detectable frequency. In many instances, the biological function of the duplicates is unknown, and hence, the significance of the presence of multiple copies of these genes remains unclear. In pathogenic E. coli isolates, the gene can be present either as a single copy or in two or more copies. We focused our work on studying why a different pathogenic E. coli strain encodes two functional copies of the gene. We show that under several environmental conditions, one of the alleles dictates IrmA expression, and the second remains silent. The latter allele is only expressed when the former is silenced. The presence of more than one functional copy of the gene in some pathogenic E. coli strains can result in sufficient expression of this virulence factor during the infection process.
基因重复显著影响真核生物和原核微生物的基因库。致病性大肠杆菌菌株的基因组共享一组重复基因，其功能大多未知。 基因是几种致病性大肠杆菌菌株中编码的重复基因之一。其基因产物的功能在尿路致病性大肠杆菌菌株 CFT073 中进行了研究，该菌株含有一个功能正常的拷贝。IrmA 蛋白结构模拟人类白细胞介素受体，可能在感染过程中发挥作用。肠聚集性大肠杆菌菌株 042 含有 基因的两个功能拷贝。在本工作中，我们研究了它们的生物学作用。 _ 等位基因在几种生长条件下表达。其表达受全局调节剂 OxyR 和 Hha 的调节，在 37°C 和营养胁迫条件下表达最佳。只有敲除 等位基因时才能检测到 _ 等位基因的表达。两个等位基因启动子区域的差异导致其表达的差异。我们的结果表明，在几种环境条件下，042 菌株中 IrmA 蛋白的表达由 _4509 等位基因决定。_2244 等位基因似乎在 _4509 等位基因失去功能时发挥备用作用，以确保 IrmA 的表达。基因重复在原核基因组中以可检测的频率发生。在许多情况下，重复基因的生物学功能未知，因此这些基因的多个拷贝的存在意义尚不清楚。在致病性大肠杆菌分离株中， 基因可以是单个拷贝，也可以是两个或更多拷贝。我们专注于研究为什么不同的致病性大肠杆菌菌株编码 基因的两个功能拷贝。我们表明，在几种环境条件下，一个等位基因决定 IrmA 的表达，而第二个保持沉默。只有当前者沉默时，后者才会表达。一些致病性大肠杆菌菌株中 基因的多个功能拷贝的存在可以导致在感染过程中该毒力因子的充分表达。
