Tsrp1 Is a Novel Cyclic Diguanosine Monophosphate Effector that Plays a Role in the Organic-Solvent Tolerance of <i>Rhodococcus ruber</i>

Cyclic diguanosine monophosphate is a ubiquitous second messenger that regulates diverse cellular processes. <i>Rhodococcus ruber</i> SD3 has potential for use in removing environmental pollutants such as phenol and toluene. In this study, Tsrp1 was found to be a novel cyclic diguanosine monophosphate effector in this strain. The interaction between Tsrp1 and c-di-GMP was verified by surface plasmon resonance, and the dissociation constant was 64 ± 6.84 μM. Moreover, in comparison with the wild-type strain, the recombinant <i>R. ruber</i> SD3 strain, which exhibited elevated levels <i>tsrp1</i> gene expression, demonstrated enhanced growth in the presence of toluene and phenol. Both recombinant <i>R. ruber</i> SD3 and the wild-type strain completely degraded toluene (0.3 g/l, 0.6 g/l and 0.9 g/l) and phenol (0.6 g/l, 0.8 g/l and 1.0 g/l) in 72 h. Furthermore, differential expression of key genes encoding transcription factors was identified based on the transcriptomic comparison between the two strains. This study is the first to describe a novel cyclic diguanosine monophosphate effector and its role in the characteristics of <i>R. ruber</i> SD3, which will shed new light on the mechanisms underlying the organic solvent tolerance of <i>R. ruber</i> SD3.