Department of Bacterial Molecular Genetics, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
Department of Medical Biology and Genetics, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
Int J Mol Sci. 2021 May 31;22(11):5890. doi: 10.3390/ijms22115890.
Bacteriophage P1 is among the best described bacterial viruses used in molecular biology. Here, we report that deficiency in the host cell DksA protein, an global transcription regulator, improves P1 lytic development. Using genetic and microbiological approaches, we investigated several aspects of P1 biology in an attempt to understand the basis of this phenomenon. We found several minor improvements in phage development in the mutant host, including more efficient adsorption to bacterial cell and phage DNA replication. In addition, gene expression of the main repressor of lysogeny C1, the late promoter activator Lpa, and lysozyme are downregulated in the mutant. We also found nucleotide substitutions located in the phage immunity region I, which may be responsible for permanent virulence of phage P1. We suggest that downregulation of C1 may lead to a less effective repression of lysogeny maintaining genes and that P1 may be balancing between lysis and lysogeny, although finally it is able to enter the lytic pathway only. The mentioned improvements, such as more efficient replication and more "gentle" cell lysis, while considered minor individually, together may account for the phenomenon of a more efficient P1 phage development in a DksA-deficient host.
P1 噬菌体是在分子生物学中应用最广泛的细菌病毒之一。在这里，我们报告称，宿主细胞 DksA 蛋白（一种全局转录调节剂）的缺乏会改善 P1 的裂解发育。我们使用遗传和微生物学方法，研究了 P1 生物学的几个方面，试图理解这一现象的基础。我们发现突变宿主中噬菌体发育有几个较小的改进，包括更有效地吸附到细菌细胞和噬菌体 DNA 复制。此外，溶原性的主要抑制剂 C1、晚期启动子激活因子 Lpa 和溶菌酶的基因表达在 突变体中下调。我们还发现了位于噬菌体免疫区 I 中的核苷酸取代，这可能是噬菌体 P1 永久毒力的原因。我们认为，C1 的下调可能导致溶原性维持基因的抑制作用降低，P1 可能在裂解和溶原之间平衡，尽管最终它只能进入裂解途径。虽然这些改进，如更有效的复制和更“温和”的细胞裂解，单独考虑可能是次要的，但它们一起可能解释了在 DksA 缺陷型宿主中 P1 噬菌体发育更有效的现象。
