RmpA drives metabolic reprogramming to modulate the phenotypic switch between hypermucoviscosity and biofilm formation in hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (hvKp) is a major cause of severe community-acquired infection. A key plasmid-encoded factor, regulator of mucoid phenotype A (RmpA), activates capsule locus gene expression to promote hypermucoviscosity, a phenotype that is strongly linked to increased pathogenicity. However, the precise regulatory mechanisms that control RmpA in hvKp remain poorly understood. In this study, we constructed a rmpA knockdown strain in hvKp using CRISPR interference and assessed the global regulatory role of RmpA through complementary multi-omic sequencing (RNA sequencing [RNA-seq] and chromatin immunoprecipitation sequencing [ChIP-seq]), promoter-gfp reporter assays, and phenotypic experiments. The functional role of RmpA was evaluated in Escherichia coli via heterologous expression. The RNA-seq analysis revealed that RmpA activates carbohydrate metabolism pathways, but represses pathways related to DNA replication, ribosome metabolism, and biofilm formation. The ChIP-seq analysis further confirmed the potential role of RmpA as a global regulator that enhances capsule production by activating transcripts within the capsule locus. It also upregulates genes involved in sugar metabolism and transport, which supplies essential precursors for capsule synthesis. RmpA modulates the phenotypic switch between hypermucoviscosity and biofilm formation by repressing type Ⅲ fimbriae genes. Notably, RmpA overexpression in E. coli induced changes in multiple metabolic pathways. These findings position RmpA as a latent central regulator in hvKp that orchestrates the metabolic pathways and phenotypic traits essential for virulence.