RESUMO
Bacterial non-coding RNAs (ncRNAs) are pivotal transcriptional regulators during bacterial proliferation and infection processes.Bacterial ncRNAs play important roles in responding to environmental changes and regulating bacterial gene expression to resist environmental stress.Transcriptome profiling of neonatal meningitis-causing Escherichia coli K1 RS218 (NMEC) reveals abundant ncRNAs.Bioinformatic analyses identified 45 potential ncRNAs.Comparative genome analyses of non-pathogenic E.coli K12 and NMEC identified 300 NMEC-specific sequences (above 100 bp), which contain 9 NMEC-specific ncRNAs (Nsr).Moreover, deletion of one ncRNA, Nsr21, enhanced NMEC survival and proliferation in mouse blood (P< 0.01) , compared to the wild-type RS218 control, in a mouse tail vein injection model.qRT-PCR analysis further revealed expression of Nsr21 decreased in NMEC collected from mouse blood compared to that in NMEC collected from in vitro medium (P<0.001) , indicating that NMEC downregulates Nsr21 expression to benefit its survival and proliferation in blood.This study suggests that the NMEC genome contains a number of ncRNAs, which may be involved in regulating NMEC pathogenicity.During infection process in the blood, NMEC enhances its proliferation ability in blood by downregulating the expression of Nsr21.