4K6R

Crystal structure of GlmU in complex with ATP

Summary for 4K6R

• Entry DOI: 10.2210/pdb4k6r/pdb
• Descriptor: Bifunctional protein GlmU, ADENOSINE-5'-TRIPHOSPHATE, MAGNESIUM ION, ... (6 entities in total)
• Functional Keywords: rossmann fold, transferase
• Biological source: Mycobacterium tuberculosis
• Total number of polymer chains: 1
• Total formula weight: 53732.31

Authors

Vithani, N.,Prakash, B. (deposition date: 2013-04-16, release date: 2014-04-16, Last modification date: 2023-11-08)

Primary citation

Vithani, N.,Bais, V.,Prakash, B.
GlmU (N-acetylglucosamine-1-phosphate uridyltransferase) bound to three magnesium ions and ATP at the active site.
Acta Crystallogr.,Sect.F, 70:703-708, 2014

PubMed Abstract: N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU), a bifunctional enzyme exclusive to prokaryotes, belongs to the family of sugar nucleotidyltransferases (SNTs). The enzyme binds GlcNAc-1-P and UTP, and catalyzes a uridyltransfer reaction to synthesize UDP-GlcNAc, an important precursor for cell-wall biosynthesis. As many SNTs are known to utilize a broad range of substrates, substrate specificity in GlmU was probed using biochemical and structural studies. The enzymatic assays reported here demonstrate that GlmU is specific for its natural substrates UTP and GlcNAc-1-P. The crystal structure of GlmU bound to ATP and GlcNAc-1-P provides molecular details for the inability of the enzyme to utilize ATP for the nucleotidyltransfer reaction. ATP binding results in an inactive pre-catalytic enzyme-substrate complex, where it adopts an unusual conformation such that the reaction cannot be catalyzed; here, ATP is shown to be bound together with three Mg2+ ions. Overall, this structure represents the binding of an inhibitory molecule at the active site and can potentially be used to develop new inhibitors of the enzyme. Further, similar to DNA/RNA polymerases, GlmU was recently recognized to utilize two metal ions, MgA2+ and MgB2+, to catalyze the uridyltransfer reaction. Interestingly, displacement of MgB2+ from its usual catalytically competent position, as noted in the crystal structure of RNA polymerase in an inactive state, was considered to be a key factor inhibiting the reaction. Surprisingly, in the current structure of GlmU MgB2+ is similarly displaced; this raises the possibility that an analogous inhibitory mechanism may be operative in GlmU.

PubMed: 24915076
DOI: 10.1107/S2053230X14008279

Experimental method

X-RAY DIFFRACTION (1.98 Å)