The mraZ-rsmH-ftsLI-murEF-mraY-murD-ftsW-murGC-ddlB-ftsQAZ-lpxC operon in E. coli contains a total of 16 genes that are also known as the division cell wall (dcw) gene cluster. These genes are involved in cell division, as well as peptidoglycan synthesis. The only terminator in the operon occurs at the end, so all 16 genes can be transcribed at one time. The operon can be repressed by the transcriptional regulator protein MraZ, which is encoded by the first gene in the operon. The operon excluding the first two proteins can also be repressed by the LexA repressor protein, which inhibits the promoter upstream of ftsL. LexA binds to the promoter region, preventing RNA polymerase from binding in response to something that would cause DNA replication to be halted. The genes after this promoter do not have additional promoters until the ftsQAZ-lpxC genes, which are further regulated. Firstly, regulatory protein SdiA can bind to the promoter upstream of ftsQ and repress the transcription of the four downstream genes. The promoter upstream of the ftsA gene can be activated by the transcriptional regulatory protein RcsB, which is involved in regulation of cell division genes and membrane protein synthesis among other functions. Finally, the compound guanosine 3'-diphosphate 5'-triphosphate (ppGpp) can bind to the promoter upstream of the ftsZ gene, activating transcription. The first gene, mraZ, encodes the transcriptional regulator protein MraZ that regulates the operon. The second gene, rsmH, encodes ribosomal RNA small subunit methyltransferase H, a protein that methylates 16S rRNA. The third gene, ftsL, encodes cell division protein FtsL, a protein that is essential for cell division and may link together cytoplasmic and periplasmic cell division proteins. The fourth gene, ftsI, encodes the peptidoglycan synthase ftsI, another protein essential for cell division that catalyzes cross-linking of the peptidoglycan in the cell wall as the cell divides. The fifth gene, murE, encodes UDP-N-acetylmuramoyl-L-alanyl-D-glutamate (UMAG) 2,6-diaminopimelate ligase. This protein is an enzyme that adds meso-diaminopimelic acid to UMAG, as part of the biosynthesis of peptidoglycan used in the bacteria's cell wall. The sixth gene, murF, encodes UDP-N-acetylmuramoyl-tripeptide--D-alanyl-D-alanine ligase. This protein is an enzyme that catalyzes the formation of UDP-N-acetylmuramoyl-pentapeptide, which is a precursor to murein, another name for peptidoglycan. The seventh gene, mraY, encodes phospho-N-acetylmuramoyl-pentapeptide-transferase. This protein is an enzyme that catalyzes the first step of lipid reactions in peptidoglycan biosynthesis. The eigth gene, murD, encodes UDP-N-acetylmuramoylalanine--D-glutamate ligase, an enzyme that catalyzes the addition of glutamate to UDP-N-acetylmuramoyl-L-alanine (UMA) as part of peptidoglycan biosynthesis. The ninth gene, ftsW, encodes a probable peptidoglycan glycosyltransferase protein that functions as a peptidoglycan polymerase. It was previously thought to be a lipid flippase, but there is evidence to suggest that MurJ is instead the flippase. The tenth gene, murG, encodes UDP-N-acetylglucosamine--N-acetylmuramyl-(pentapeptide) pyrophosphoryl-undecaprenol N-acetylglucosamine transferase. This protein is involved in cell wall formation, catalyzing the formation of undecaprenyl-pyrophosphoryl-MurNAc-(pentapeptide)GlcNAc. The eleventh gene, MurC, encoes UDP-N-acetylmuramate--L-alanine ligase, a protein that is involved in peptidoglycan biosynthesis and cell wall formation. The twelfth gene, ddlB, encodes D-alanine--D-alanine ligase B, a protein that catalyzes the addition of two D-alanine molecules together to form D-alanyl-D-alanine, which is involved in peptidoglycan biosynthesis. The thirteenth gene, ftsQ, encodes cell divison protein FtsQ, an essential cell division protein. It may, along with ftsI, link cytoplasmic and periplasmic cell divions proteins, as well as potentially help formation of the divisome. The divisome is a protein comple that controls cell division. The fourteenth gene, ftsA, encodes cell division protein FtsA, a protein essential for cell division that helps with the formation and possible anchoring of the Z-ring. The Z-ring is formed from FtsZ protein filaments that form a ring around the centre of the cell and triggers splitting of the cell in two. The fifteenth gene, ftsZ, encodes cell division protein FtsZ, which is responsible for forming the Z-ring or contractile ring where the cell will divide. The final gene in the operon, lpxC, encodes UDP-3-O-acyl-N-acetylglucosamine deacetylase. This protein is involved in the biosynthesis of lipid A, a lipid compound found on the outer membrane of gram negative bacteria. Lipid A is considered an endotoxin, and is partially responsible for the activation of an immune response to gram negative bacterial infection.

Operon: dcw cluster Genes References