EC Number   |
General Information |
Reference |
|---|
   4.2.1.115 | evolution |
CapE belongs to a distinctive subfamily of SDR enzymes of pathogenic bacteria characterized by a singular catalytic triad displaying a Met residue (instead of the canonical Tyr residue) and a dynamic element known as the latch. Although CapE and FlaA1 afford the same product, the configuration of their active sites is different. Also, the latch region is absent in FlaA1 |
729735 |
| 4.2.1.115 | evolution |
UDP-GlcNAc inverting 4,6-dehydratases can be divided into two subfamilies, based on the conservation of the canonical YXXXK motif at the active site, like FlaA1, or the presence of an altered motif, MXXXK, where the catalytic tyrosine is replaced by a methionine, represented by CapE. Mg534 is a 4,6-dehydratase 5-epimerase, its three-dimensional structure suggests that it belongs to a third subfamily of inverting dehydratases. The Mg534 protein exhibits the canonical catalytic triad containing the 140YXXXK144 motif present in other SDR enzymes |
748176 |
| 4.2.1.115 | metabolism |
conversion of UDP-D-GlcNAc into UDP-L-FucNAc, an essential precursor of capsular polysaccharide requires three enzymes CapE, CapF, and CapG in Staphylococcus aureus. CapE yields the first intermediate of the sequential reactions catalyzed by these three enzymes |
729735 |
| 4.2.1.115 | metabolism |
the first reaction that leads to the formation of the UDP-2-acetamido-2,6-dideoxy-beta-L-hexoses is the dehydration of UDP-D-GlcNAc catalyzed by enzyme Mg534. Mg534 is a 4,6-dehydratase 5-epimerase, an inverting dehydratase. Enzyme Mg535, next in the glycan synthesis pathway, is a bifunctional 3-epimerase 4-reductase. The sequential activity of the two enzymes leads to the formation of UDP-L-N-acetylrhamnosamine (UDP-L-RhaNAc). Pathway for the biosynthesis of UDP-2-acetamido-2,6-dideoxy-hexoses, overview |
748176 |
| 4.2.1.115 | more |
two different types of enzymes are identified. In one case, this step is a simple dehydration with formation of UDP-2-acetamido-2,6-dideoxy-alpha-D-xylo-4-hexulose, which is typical of the UDP-bacillosamine or UDP-N-acetyl-D-fucosamine and UDP-N-acetyl-D-quinovosamine pathways. In other cases, the enzymes are inverting 4,6-dehydratases, catalyzing also the epimerization of C-5, with the consequent inversion of the D-configuration to L-, and the formation of UDP-2-acetamido-2,6-dideoxy-beta-L-arabino-4-hexulose. This reaction is catalyzed by PseB/FlaA1 in the case of the pseudaminic acid (Pse) pathway, where the transfer of an amino group to the C-4 carbonyl follows this first step. Superposition of the NADPH binding domain of Mg534 with CapE highlights a large conformational change of the substrate binding domain that reflects the dynamic of the structure during the catalysis. In absence of the substrate, the domain is rotated and closes the substrate binding pocket. Upon incubation with Mg535 and a system for NADPH regeneration, the Mg534 product is converted to a compound with a retention time similar to UDP-GlcNAc |
748176 |
| 4.2.1.115 | physiological function |
CapE is an essential enzyme for the synthesis of capsular polysaccharide of pathogenic strains of Staphylococcus aureus |
729735 |
| 4.2.1.115 | physiological function |
the enzyme is involved in the Pse pathway for biosynthesis of glycans of the heavily glycosylated fibrils surrounding the viral capsids. Megavirus glycans are mainly composed of virally synthesized N-acetylglucosamine (GlcNAc). They also contain N-acetylrhamnosamine (RhaNAc), a rare sugar. The enzymes involved in its synthesis are encoded by a gene cluster specific to Megavirus close relatives. GC-MS analyses of Megavirus glycoconjugates |
748176 |
