Fig. 9: Model of K. pneumoniae regulation of mucoidy in response to arginine.
From: Arginine regulates the mucoid phenotype of hypervirulent Klebsiella pneumoniae
When cultured in the presence of arginine, K. pneumoniae increases mucoidy without altering the total capsule abundance. When arginine is brought into the cell, the arginine regulator, ArgR, binds arginine and becomes active. The activated ArgR-arginine complex acts as a transcriptional regulator via binding to ARG boxes. The arginine-ArgR complex binds directly to the Prmp ARG box and activates the rmpADC promoter, upregulating rmpADC transcription. The RmpD protein then interacts with the Wzc protein, a tyrosine autokinase that regulates high-level capsular polysaccharide (CPS) polymerization. RmpD-Wzc interactions decrease ‘Type A’ polysaccharide chains and increases ‘Type B’, which decreases CPS diversity and presents as the mucoid phenotype resulting in decreased association with macrophages. Created in BioRender. Ryan, B. (2025) https://BioRender.com/r74w727.
