Identification of non-coding RNA AsfD in Salmonella enterica serovar Typhi and its expressional characteristics
LIU Rui 1, ZHONG Xiao-dan 2, ZHAO Xin 1, LU Ren-fei 1, SUN Jia-yao 1, HUANG Xin-xiang 1
(1. School of Medicine, Jiangsu University, Zhenjiang Jiangsu 212013； 2. Department of Oncology, Institute of Translational Medicine, the Second Military Medical University, Shanghai 200433, China)
Abstract：[Abstract]Objective: To study the molecular and expressional characteristics of the putative non-coding RNA AsfD which is encoded by the opposite strand of flhDC gene in Salmonella enteric serovar Typhi(S. Typhi). Methods: Specific probe primers were designed in the known sequence region of AsfD and RNA probes were prepared in vitro. Northern blotting assay was then used to detect the expression of the AsfD in S. Typhi. 5′rapid amplification of cDNA ends(RACE) and RT-PCR were used to analyze the transcription start site and termination region of AsfD.qRT-PCR was used to detect the expressional characteristics of AsfD at different growth phases and environmental stresses in S. Typhi. Results: The results of the Northern blotting showed that expression of AsfD with a length of about 2 300 nt did exist in S. Typhi. According to the results of 5′RACE, the transcription start site of AsfD was 590 bp downstream of the flhC gene stop codon; RT-PCR showed transcription termination region was 558-788 bp upstream of the flhD gene start codon. No obvious ORF structure was found in the AsfD. The results of qRT-PCR showed AsfD expression level was high in the stationary phase of S. Typhi and significantly decreased in environmental acid, oxidative and osmotic stresses(P<0.01). Conclusion: AsfD is a long non-coding RNA and the expression can be regulated at different growth phase and stress conditions in S. Typhi.
［Key words］Salmonella enterica serovar Typhi; non-coding RNA; AsfD; environmental stress
2008, Vol. 28 
