CDP-ribitol

This enzyme [EC 2.7.7.40], also known as CDP-ribitol pyrophosphorylase, catalyzes the reaction of CTP with D-ribitol 5-phosphate to produce CDP-ribitol and pyrophosphate (or, diphosphate). 

Fig. 3. Binding curve of a DNA aptamer that is selected to bind a protein enzyme known as Bcs1. Bcs1 is a CDP-ribitol synthase (a bifunctional enzyme that catalyzes two consecutive chemical reactions leading to the formation of CDP-ribitol the reduction of ribulose 5-phosphate using NADPH, and cytidylyltransfer using CTP) from Haemophilus influenzae.JM is the corresponding CDP-ribitol synthase from Staphylococcus aureus. Radioactively labeled DNA aptamer (—0.1 nM) was incubated with 0, 25, 50, 75,100, and 200 nM of each enzyme in the selection buffer and the mixtures were analyzed using 8% nondenaturing polyacrylamide gel. The fraction of radioactivity in the shifted DNA band is calculated and plotted against the protein concentration.

Biosynthesis of ribitol T.a. is by progressive transfer of n-ribitol 5-phosphate units from CDP-ribitol to position 1 of the previous unit it is not known at which stage the sugar and alanine residues are added. Similarly, glycerol T. a. are biosynthesized from CDP-glycerol. 

Teichoic acids consist of polyolphosphate homopolymers to which sugars and amino acids are attached they are found in bacterial cell walls. There are two common types, in which glycerol phosphate and ribitol phosphate, respectively, constitute the repeating units. These are transferred to the appropriate primer through the corresponding nucleotide derivative, CDP-glycerol or CDP-ribitol. 

The nucleotide coenzymes are structurally related to the mononucleotides. Typical nucleotide coenzymes are adenosine triphosphate (ATP), flavin-adenine-dinucleotide (FAD) and numerous other phosphate esters of complex structure, containing adenosine, guanosine, cytidine or uridine. Five coenzymes are known for example, which are derived from cytidine diphosphate (CDP) CDP-choline, CDP-ethanolamine, CDP-diglyceride, CDP-glycerol and CDP-ribitol. 

Figure 2.8 The Structures of the Teichoic Acid Precursors, CDP-glycerol and CDP-ribitol...

Pereira, M.P. and Brown, E.D. (2004) Bifunctional catalysis by CDP-ribitol synthase Convergent recruitment of reductase and cytidy-lyltransferase activities in Haemophilus influenzae sad. Staphylococcus aureus. Biochemistry (Mosc). 

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