3DK5

Crystal Structure of Apo-GlmU from Mycobacterium tuberculosis

Summary for 3DK5

• Entry DOI: 10.2210/pdb3dk5/pdb
• Related: 3DIU 3DJ4
• Descriptor: Bifunctional protein glmU, MAGNESIUM ION (3 entities in total)
• Functional Keywords: acetyltransferase, bifunctional, pyrophosphorylase, rossmann-like fold, left-handed-beta-helix, trimer, cell shape, cell wall biogenesis/degradation, cytoplasm, magnesium, metal-binding, multifunctional enzyme, nucleotidyltransferase, peptidoglycan synthesis, transferase
• Biological source: Mycobacterium tuberculosis
• Cellular location: Cytoplasm (By similarity): A5U161
• Total number of polymer chains: 1
• Total formula weight: 51686.34

Authors

Verma, S.K.,Prakash, B. (deposition date: 2008-06-24, release date: 2009-05-19, Last modification date: 2024-03-20)

Primary citation

Parikh, A.,Verma, S.K.,Khan, S.,Prakash, B.,Nandicoori, V.K.
PknB-mediated phosphorylation of a novel substrate, N-acetylglucosamine-1-phosphate uridyltransferase, modulates its acetyltransferase activity.
J.Mol.Biol., 386:451-464, 2009

PubMed Abstract: Identifying direct targets of kinases and determining how their activities are regulated are central to understanding how they generate biological responses. Genetic and biochemical studies have shown that Mycobacterium tuberculosis serine/threonine protein kinases PknA and PknB play a role in modulating cell shape and possibly cell division. In this report, we show that the enzyme N-acetylglucosamine-1-phosphate uridyltransferase (GlmU) of M. tuberculosis is a novel substrate of PknB and is phosphorylated on threonine residues. GlmU carries out two important biochemical activities: a C-terminal domain catalyzes the transfer of acetyl group from acetyl coenzyme A to glucosamine-1-phosphate to produce N-acetylglucosamine-1-phosphate, which is converted into UDP-N-acetylglucosamine by the transfer of uridine 5'-monophosphate (from uridine 5'-triphosphate), a reaction catalyzed by the N-terminal domain. We determined the crystal structures of GlmU in apo form and UDP-N-acetylglucosamine-bound form, and analyzed them to identify threonine residues that may be accessible to PknB. The structure shows a two-domain architecture, with an N-terminal domain having an alpha/beta-like fold and with a C-terminal domain that forms a left-handed parallel beta-helix structure. Kinase assays with PknB using the N- and C-terminal domains of GlmU as substrates illustrated that PknB phosphorylates GlmU in the C-terminal domain. Furthermore, mutational studies reveal one of the five threonines present in region 414-439 to be phosphorylated by PknB. Structural and biochemical analyses have shown the significance of a variable C-terminal tail in regulating acetyltransferase activity. Notably, we demonstrate that although PknB-mediated phosphorylation of GlmU does not affect its uridyltransferase activity, it significantly modulates the acetyltransferase activity. These findings imply a role for PknB in regulating peptidoglycan synthesis by modulating the acetyltransferase activity of GlmU.

PubMed: 19121323
DOI: 10.1016/j.jmb.2008.12.031

Experimental method

X-RAY DIFFRACTION (2.23 Å)