Bacterial group II introns: splicing, function and evolution

我们的研究项目的目标是研究与细菌II组内含子相关的剪接、功能和进化问题。在第一个倡议中，我们研究了第二组内含子的反式剪接，以解决第二组内含子，核内含子和五个小RNA的剪接机制，剪接体的一部分之间的进化关系。其次，我们正在探索细菌细胞中II组内含子的各种剪接途径。最后，我们研究了这些retromobile元素的传播细菌物种之间的接合和转导。我们的模型系统是来自乳酸乳球菌的Ll.LtrB II组内含子。L.乳酸菌是工业上重要的低G+C革兰氏阳性细菌，主要用于乳制品工业中生产奶酪和酸奶。LtrB与L. lactis：pRS01和pAH90质粒以及染色体性别因子。因此，我们正在研究，如果通过共轭的L。细菌细胞之间的乳酸菌性因子可以支持它所传递的Ll.LtrB内含子的传播。我们还研究了Ll.LtrB内含子是否可以通过各种噬菌体在细菌界中传播（转导）。将L.为了研究Ll.LtrB移动的II组内含子在其新的细胞环境中的重新插入，我们将研究Ll.将研究L1.LtrB内含子重新插入同源和非同源位点。我们还研究了细菌细胞中II组内含子的各种剪接途径，以及它们被片段化并仍在反式剪接的能力。这将使我们能够解决核内含子及其剪接机制的起源问题。

The goal of our research program is to study splicing, function and evolutionary questions related to bacterial group II introns. In a first initiative we study trans-splicing of group II introns in order to address the evolutionary relationships between group II introns, nuclear introns and the five small RNAs that are part of the splicing machinery, the spliceosome. Secondly, we are exploring the various splicing pathways of group II introns in bacterial cells. Finally, we study the dissemination of these retromobile elements by conjugation and transduction between bacterial species. Our model system is the Ll.LtrB group II intron from Lactococcus lactis. L. lactis is an industrially important low G+C Gram-positive bacterium mainly used in the dairy industry for the production of cheese and yogurt. Ll.LtrB was found associated with different conjugative elements in L. lactis: the pRS01 and pAH90 plasmids and the chromosomal sex factor. We are thus studying if the transfer by conjugation of the L. lactis sex factor between bacterial cells can support the spread of the Ll.LtrB intron it conveys. We also study if the Ll.LtrB intron can be disseminated in the bacterial kingdom by various bacteriophages (transduction). After transfer of the intron-carrying elements from L. lactis to different bacterial species, we will study the reinsertion of the Ll.LtrB mobile group II intron in its new cell environment. Reinsertion of the Ll.LtrB intron into homologous and non-homologous sites will be studied. We are also studying the various splicing pathways of group II introns in bacterial cells and their capacity to be fragmented and still splice in trans. This will allow us to address the origin of nuclear introns and their splicing machinery.