Integral membrane undecaprenol kinase and similar enzymes
This mostly bacterial family of homo-trimeric integral membrane enzymes, the products of the dgkA gene, catalyzes the ATP-dependent phosphorylation of undecaprenol to undecaprenyl phosphate. C55-isoprenyl (undecaprenyl) pyroposphate acts as a scaffold for the assembly of peptidoglycan components; undecaprenol kinase (UDPK) is involved in recycling undecaprenyl units for re-use in the peptidoglycan biosynthesis. UDPK does not participate in the de-novo biosynthesis of undecaprenyl phosphate. Gram-positive bacteria have a large pool of free undecaprenol, in contrast to gram-negative bacteria. UDPK may also play a role in a stress-induced pathway that affects the function of ribosomes. In Streptococcus mutans, UDPK has been shown to be required for biofilm formation, such as in the case of smooth surface dental caries. Members of the UDPK family have low activity as diacylglycerol kinases (DAGK), and many of them are annotated as DAGKs.
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