The Phosphoenolpyruvate Phosphotransferase System Regulates Vibrio cholerae Biofilm Formation through Multiple Independent Pathways

Abstract

The bacterial phosphoenolpyruvate phosphotransferase system (PTS) is a highly conserved phosphotransfer cascade that participates in the transport and phosphorylation of selected carbohydrates and modulates many cellular functions in response to carbohydrate availability. It plays a role in the virulence of many bacterial pathogens. Components of the carbohydrate-specific PTS include the general cytoplasmic components enzyme I (EI) and histidine protein (HPr), the sugar-specific cytoplasmic components enzymes IIA (EIIA) and IIB (EIIB), and the sugar-specific membrane-associated multisubunit components enzymes IIC (EIIC) and IID (EIID). Many bacterial genomes also encode a parallel PTS pathway that includes the EI homolog EI Ntr , the HPr homolog NPr, and the EIIA homolog EIIA Ntr . This pathway is thought to be nitrogen specific because of the proximity of the genes encoding this pathway to the genes encoding the nitrogen-specific factor 54 . We previously reported that phosphorylation of HPr and FPr by EI represses Vibrio cholerae biofilm formation in minimal medium supplemented with glucose or pyruvate. Here we report two additional PTS-based biofilm regulatory pathways that are active in LB broth but not in minimal medium. These pathways involve the glucose-specific enzyme EIIA (EIIA Glc ) and two nitrogen-specific EIIA homologs, EIIA Ntr1 and EIIA Ntr2 . The presence of multiple, independent biofilm regulatory circuits in the PTS supports the hypothesis that the PTS and PTS-dependent substrates have a central role in sensing environments suitable for a surface-associated existence.

Biochemical Characterization of a Nitrogen-Type Phosphotransferase System Reveals that Enzyme EI Ntr Integrates Carbon and Nitrogen Signaling in Sinorhizobium meliloti

“…The systems controlled by the PTS Ntr vary greatly among bacteria, from nitrogen fixation and polyhydroxybutyrate accumulation in Azotobacter vinelandii, to oligopeptide transport in Bradyrhizobium japonicum, pathogenesis in Brucella melitensis, biofilm formation in Vibrio cholerae, and potassium homeostasis and tricar- boxylic acid (TCA) cycle flux in E. coli (33)(34)(35)(36)(37)(38)(39). In S. meliloti, the PTS Ntr lacks membrane-bound transporters, making it strictly regulatory, and leaving the uptake of catabolites primarily to ABC and TRAP transporters (17).…”

The Bacterial Phosphoenolpyruvate:Carbohydrate Phosphotransferase System: Regulation by Protein Phosphorylation and Phosphorylation-Dependent Protein-Protein Interactions

“…This protein controls the expression of the manLMNO operon, which encodes the major glucose transporter of this human pathogen (78,150). However, ManR activity is regulated not by the components of the mannose-type PTS ManLMN but by the proteins of another mannose-type PTS, MpoABCD, a low-affinity glucose/mannose-specific PTS that functions mainly as glucose sensor (78 PTS components also play a role in biofilm formation, as has been shown for EI and HPr of V. cholerae (151). In a recent study, the utilization of mannitol by this organism was reported to activate biofilm formation and the expression of the vps genes, which encode the proteins required for the synthesis of the exopolysaccharides forming the biofilm matrix (152).…”

Integration of Global Regulatory Mechanisms Controlling Vibrio Cholerae Behavior

“…Biofilm formation is also modulated by interplay between the positive transcription regulators, VpsT (Casper-Lindley & Yildiz, 2004) and VpsR (Yildiz et al, 2001), and the negative regulator, CytR (Haugo & Watnick, 2002). In addition, vps expression is modulated by the PhoBR two-component regulatory system (Pratts et al, 2009(Pratts et al, , 2010Sultan et al, 2010) and by components of the PTS phosphoryl cascade (Houot et al, 2008;, 2010a.…”

“…Pretreatment of mice with commensal bacteria engineered to express CAI-1 affords protection against a cholera challenge (Duan and March, 2010). A second set of attractive targets are the PTS components that modulate biofilm formation (Houot et al, 2008(Houot et al, , 2010(Houot et al, , 2010a. A comparative genomic analysis of 202 fully sequenced genomes (174 bacterial, 19 archaeal, and 9 eukaryotic) did not reveal components of the PTS system in eukaryotic cells (Barabote et al, 2005).…”