Expression of translation elongation factor P in Kocuria rhizophila is regulated by an inducible weak promoter

Translation elongation factor P (EF-P), encoded by the efp gene, plays a crucial role in bacterial physiology, virulence, and stress response. Revealing the regulation of EF-P expression in bacteria is an important basis for revealing the molecular mechanisms underlying the aforementioned biomolecular functions. In this study, Kocuria rhizophila DC2201, a commonly used strain in quality control, was used as the research subject, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) was employed to assess the effects of temperature, pH, and antibiotics on efp transcription. The efp promoter (designated as Pefp) in K. rhizophila was predicted using bioinformatics tools and validated through the construction of promoter mutants and the development of promoter functional validation plasmids. Under high temperatures (37 °C, 40 °C), efp expression in K. rhizophila is down-regulated during the exponential phase and then up-regulated during the stationary phase. Under acidic (pH 5.2) and alkaline (pH 9.2) stress conditions, efp expression is up-regulated during the exponential phase. When exposed to 0.5 × MIC of clindamycin, an antibiotic stress, efp expression is significantly increased at all growth stages. The Pefp in K. rhizophila is located at positions 1,507,586–1507377 in the genome (NCBI Reference Sequence: NC_010617.1), with core regions including the − 10 (CATCAT) and − 35 (TGGACC) regions; this promoter exhibits lower activity compared to the T7 promoter and the promoter from the glyceraldehyde-3-phosphate dehydrogenase gene (Pgadph) of K. rhizophila DC2201. The results revealed that the efp expression in K. rhizophila is inducible, and the Pefp is a weak promoter. These findings could lay the groundwork for identifying transcription factors involved in efp gene expression and further exploring the transcriptional regulation of EF-P in K. rhizophila.