The manXYZ operon in E. coli contains three genes that encode for different components of the sugar phosphotransferase system (PTS system) enzyme II. This enzyme is involved specifcally in the transport of mannose. This operon can be inhibited by the DNA-binding transcriptional repressor Mlc, which binds to the regulatory region of the operon, preventing its transcription. It can also be inhibited by the DNA-binding transcriptional dual regulator Cra, which forms a complex with DNA to prevent transcription. However, if beta-D-fructofuranose 1-phosphate is present, it will bind to Cra and prevent it from binding to the DNA, allowing the genes to be transcribed. The final inhibitor of the manXYZ operon is the N-acetylglucosamine repressor NagC, which also binds to DNA to inhibit transcription of the operon. However, similar to Cra, it can be bound by N-acetyl-D-glucosamine 6-phosphate, which prevents it from binding to the DNA, and stops the inhibition of the operon. The first gene in the operon, manX, encodes the PTS system mannose-specific EIIAB component protein with an A and B domain that are linked. The protein is a dimer in the cell, and is found in the inner membrane of the bacteria, as it is a protein that allows mannose to enter the cell. The second gene, manY, encodes the mannose permease IIC component, which is found in the cell's inner membrane as part of the permease complex. The protein products of manX and manY are required for lambda phage infection of the cell, as they likely form the pore that allows for its DNA to penetrate the cell. The final gene, manZ, encodes the mannose permease IID component. This protein is found in the cell's inner membrane along with the other two components, and is responsible for forming the transmembrane channel, along with the ManY protein.

Operon: Mannose Uptake Inactivation References