Engineering transcriptional regulation to control Pdu microcompartment formation

Area of Science:

• * Synthetic biology
• * Bacterial cell biology
• * Metabolic engineering

Background:

• * Bacterial microcompartments (MCPs) are protein shells that encapsulate enzymes for specific metabolic pathways.
• * Efficient formation of MCPs is crucial for both native functions and engineered applications, requiring precise regulation.
• * The propanediol utilization (Pdu) MCP system is induced by growth on 1,2-propanediol, involving the Pdu operon.

Purpose of the Study:

• * To investigate the regulatory mechanisms controlling the formation of the Pdu MCP.
• * To develop a reporter system for studying the activation of the Pdu operon promoter (Ppdu).
• * To explore the role of the transcriptional activator PocR in Pdu MCP formation and function.

Main Methods:

• * Construction of a fluorescence-based transcriptional reporter for the Ppdu promoter.
• * Culturing bacterial strains under various media conditions (rich media, presence/absence of glucose and 1,2-propanediol).
• * Heterologous expression of the transcriptional activator PocR to assess its effect on MCP formation.

Main Results:

• * Pdu MCPs can be expressed in rich media without glucose, as indicated by the reporter system.
• * PocR is essential for Pdu MCP formation, as confirmed by reporter activity and MCP assembly.
• * Heterologous expression of PocR induces Pdu MCP formation independently of 1,2-propanediol and glucose, and these MCPs are functional in vivo.

Conclusions:

• * The transcriptional activator PocR is a key regulator for Pdu MCP formation.
• * Overexpression of PocR provides a method to induce and potentially engineer MCP formation, size, and number.
• * This regulatory strategy has implications for the synthetic biology applications of MCPs.