(B4) Moreover, Ser404 as well as mainchain amide of Ala379 stabilizes the negative charge on the thioester carbonyl during the transition state. This protein is a bifunctional enzyme, catalyzing two sequential reactions, with two distinct domains. The first domain functions as a uridylyltransferase (EC 2.7.7.23), which catalyzes the second reaction, whilst the second domain serve as a acetyltransferase (EC 2.3.1.157) that catalyzes the first one (see [4]). (A) Phosphoryl transfer: Papers [6] & [7] mentioned catalytic mechanism of uridylyltransferase (EC 2.7.7.23). The paper [7] proposed a catalytic mechanism, in which transphosphorylation is assumed to proceed through SN2 mechanism. In the proposed mechanism, the reaction proceeds as follows: (A1) A non-esterified phosphate oxygen atom of GlcNAc-1-P makes a nucleophilic attack on the alpha-phosphate group of UTP, forming penta-coordinated phosphorane transition state with the attacking group and leaving group, pyrophosphate. (A2) Here, the transition state might be stabilized by the positive charge of Mg2+ ion, which is bound to the oxygen atoms from the transferred alpha-phosphate group and attacking phosphate group as well as Asp102 and Asn227 (PDB;1g97), and the sidechain amino group of Lys22 (PDB;1g97). On the other hand, the leaving pyrophosphate can be stabilized by Arg15 (PDB;1g97). (A3) The transfer reaction results in the inversion of the configuration at the alpha-phosphate group. (B) Acyl transfer: Paper [9] proposed a catalytic mechanism for acyltransferase (EC 2.3.1.157). According to the paper [9], the reaction proceeds as follows: (B1) Glu348, hydrogen bonding to His362, might modulate the activity of His362. (B2) His362 (PDB;1hm9) function as a general base, which activates the acceptor amine group of glucosamine-1-P, by abstracting a proton from the amine group. (B3) The amine group can make a nucleophilic attack on the acyl group of acetyl-CoA.
Spore Coat Polysaccharide Biosynthesis Protein SpsA; Chain A
UDP N-Acetylglucosamine Acyltransferase; domain 1
UDP-N-acetylglucosamine pyrophosphorylase
uridine diphosphoacetylglucosamine pyrophosphorylase
Acetylglucosamine 1-phosphate uridylyltransferase
uridine diphosphate-N-acetylglucosamine pyrophosphorylase
uridine diphosphoacetylglucosamine phosphorylase
glucosamine-1-phosphate N-acetyltransferase
N-Acetyl-alpha-D-glucosamine 1-phosphate
Crystal structures of Streptococcus pneumoniae N-acetylglucosamine-1-phosphate uridyltransferase, GlmU, in apo form at 2.33 A resolution and in complex with UDP-N-acetylglucosamine and Mg(2+) at 1.96 A resolution.
Purification, crystallization and preliminary X-ray data for Escherichia coli GlmU: a bifunctional acetyltransferase/uridyltransferase.
Identification of the glmU gene encoding N-acetylglucosamine-1-phosphate uridyltransferase in Escherichia coli.
Copurification of glucosamine-1-phosphate acetyltransferase and N-acetylglucosamine-1-phosphate uridyltransferase activities of Escherichia coli: characterization of the glmU gene product as a bifunctional enzyme catalyzing two subsequent steps in the pathway for UDP-N-acetylglucosamine synthesis.
Synthesis of 5-IASA-UDP-GlcNAc and its use for the photoaffinity labeling of a novel UDP-GlcNAc pyrophosphorylase.
Acetyltransfer precedes uridylyltransfer in the formation of UDP-N-acetylglucosamine in separable active sites of the bifunctional GlmU protein of Escherichia coli.
Probing the role of cysteine residues in glucosamine-1-phosphate acetyltransferase activity of the bifunctional GlmU protein from Escherichia coli: site-directed mutagenesis and characterization of the mutant enzymes.
Crystal structure of the bifunctional N-acetylglucosamine 1-phosphate uridyltransferase from Escherichia coli: a paradigm for the related pyrophosphorylase superfamily.
Dissection of the bifunctional Escherichia coli N-acetylglucosamine-1-phosphate uridyltransferase enzyme into autonomously functional domains and evidence that trimerization is absolutely required for glucosamine-1-phosphate acetyltransferase activity and cell growth.
Crystal structure of Streptococcus pneumoniae N-acetylglucosamine-1-phosphate uridyltransferase bound to acetyl-coenzyme A reveals a novel active site architecture.
Structure of the Escherichia coli GlmU pyrophosphorylase and acetyltransferase active sites
Crystal structure of Escherichia coli glucose-1-phosphate thymidylyltransferase (RffH) complexed with dTTP and Mg2+.