Removal of a Membrane Anchor Reveals the Opposing Regulatory Functions of Vibrio cholerae Glucose-Specific Enzyme IIA in Biofilms and the Mammalian Intestine

ABSTRACT

The Vibrio cholerae phosphoenolpyruvate phosphotransferase system (PTS) is a well-conserved, multicomponent phosphotransfer cascade that coordinates the bacterial response to carbohydrate availability through direct interactions of its components with protein targets. One such component, glucose-specific enzyme IIA (EIIA^Glc), is a master regulator that coordinates bacterial metabolism, nutrient uptake, and behavior by direct interactions with cytoplasmic and membrane-associated protein partners. Here, we show that an amphipathic helix (AH) at the N terminus of V. cholerae EIIA^Glc serves as a membrane association domain that is dispensable for interactions with cytoplasmic partners but essential for regulation of integral membrane protein partners. By deleting this AH, we reveal previously unappreciated opposing regulatory functions for EIIA^Glc at the membrane and in the cytoplasm and show that these opposing functions are active in the laboratory biofilm and the mammalian intestine. Phosphotransfer through the PTS proceeds in the absence of the EIIA^Glc AH, while PTS-dependent sugar transport is blocked. This demonstrates that the AH couples phosphotransfer to sugar transport and refutes the paradigm of EIIA^Glc as a simple phosphotransfer component in PTS-dependent transport. Our findings show that Vibrio cholerae EIIA^Glc, a central regulator of pathogen metabolism, contributes to optimization of bacterial physiology by integrating metabolic cues arising from the cytoplasm with nutritional cues arising from the environment. Because pathogen carbon metabolism alters the intestinal environment, we propose that it may be manipulated to minimize the metabolic cost of intestinal infection.

IMPORTANCE The V. cholerae phosphoenolpyruvate phosphotransferase system (PTS) is a well-conserved, multicomponent phosphotransfer cascade that regulates cellular physiology and virulence in response to nutritional signals. Glucose-specific enzyme IIA (EIIA^Glc), a component of the PTS, is a master regulator that coordinates bacterial metabolism, nutrient uptake, and behavior by direct interactions with protein partners. We show that an amphipathic helix (AH) at the N terminus of V. cholerae EIIA^Glc serves as a membrane association domain that is dispensable for interactions with cytoplasmic partners but essential for regulation of integral membrane protein partners. By removing this amphipathic helix, hidden, opposing roles for cytoplasmic partners of EIIA^Glc in both biofilm formation and metabolism within the mammalian intestine are revealed. This study defines a novel paradigm for AH function in integrating opposing regulatory functions in the cytoplasm and at the bacterial cell membrane and highlights the PTS as a target for metabolic modulation of the intestinal environment.