School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia.
Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia.
Mol Microbiol. 2021 Jul;116(1):154-167. doi: 10.1111/mmi.14697. Epub 2021 Feb 24.
Incompatibility group C (IncC) plasmids are large (50-400 kb), broad host range plasmids that drive the spread of genes conferring resistance to all classes of antibiotics, most notably the bla gene that confers resistance to last-line carbapenems and the mcr-3 gene that confers resistance to colistin. Several recent studies have improved our understanding of the basic biological mechanisms driving the success of IncC, in particular the identification of multiple novel IncC conjugation genes by transposon directed insertion-site sequencing. Here, one of these genes, dtrJ, was examined in further detail. The dtrJ gene is located in the DNA transfer locus on the IncC backbone, and quantitative reverse-transcriptase PCR analysis revealed it is transcribed in the same operon as the DNA transfer genes traI and traD (encoding the relaxase and coupling protein, respectively) and activated by the AcaDC regulatory complex. We confirmed that DtrJ is not required for pilus biogenesis or mate pair formation. Instead, DtrJ localizes to the membrane, where it interacts with the coupling protein TraD and functions as an IncC DNA transfer protein. Overall, this work has defined the role of DtrJ in DNA transfer of IncC plasmids during conjugation.
C 组不相容性质粒（IncC）是大型（50-400kb）、广谱宿主范围质粒，推动了赋予所有抗生素类耐药性的基因的传播，特别是赋予最后一线碳青霉烯类耐药性的 bla 基因和赋予多粘菌素耐药性的 mcr-3 基因。最近的几项研究提高了我们对推动 IncC 成功的基本生物学机制的理解，特别是通过转座子定向插入位点测序鉴定了多个新的 IncC 接合基因。在这里，对其中一个基因 dtrJ 进行了更详细的研究。dtrJ 基因位于 IncC 骨架的 DNA 转移基因座上，定量逆转录-PCR 分析显示，它与 DNA 转移基因 traI 和 traD（分别编码松弛酶和偶联蛋白）在同一个操纵子中转录，并由 AcaDC 调节复合物激活。我们证实 DtrJ 不参与菌毛生物发生或配对形成。相反，DtrJ 定位于膜上，与偶联蛋白 TraD 相互作用，作为 IncC DNA 转移蛋白发挥作用。总的来说，这项工作定义了 DtrJ 在接合过程中 IncC 质粒 DNA 转移中的作用。
