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Crystal structures of Mycobacterium tuberculosis GlgE and complexes with non-covalent inhibitors.

Lindenberger JJ, Veleti SK, Wilson BN, Sucheck SJ, Ronning DR - Sci Rep (2015)

Bottom Line: The maltohexaose structure reveals a dominant site for α-glucan binding.To obtain more detailed interactions between first generation, non-covalent inhibitors and GlgE, a variant Streptomyces coelicolor GlgEI (Sco GlgEI-V279S) was made to better emulate the Mtb GlgE M1P binding site.These structures detail important interactions that contribute to the inhibitory activity of these compounds, and provide information on future designs that may be exploited to improve upon these first generation GlgE inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Biochemistry, The University of Toledo, 2801 W. Bancroft St. Ms602, Toledo, OH, United States.

ABSTRACT
GlgE is a bacterial maltosyltransferase that catalyzes the elongation of a cytosolic, branched α-glucan. In Mycobacterium tuberculosis (M. tb), inactivation of GlgE (Mtb GlgE) results in the rapid death of the organism due to a toxic accumulation of the maltosyl donor, maltose-1-phosphate (M1P), suggesting that GlgE is an intriguing target for inhibitor design. In this study, the crystal structures of the Mtb GlgE in a binary complex with maltose and a ternary complex with maltose and a maltosyl-acceptor molecule, maltohexaose, were solved to 3.3 Å and 4.0 Å, respectively. The maltohexaose structure reveals a dominant site for α-glucan binding. To obtain more detailed interactions between first generation, non-covalent inhibitors and GlgE, a variant Streptomyces coelicolor GlgEI (Sco GlgEI-V279S) was made to better emulate the Mtb GlgE M1P binding site. The structure of Sco GlgEI-V279S complexed with α-maltose-C-phosphonate (MCP), a non-hydrolyzable substrate analogue, was solved to 1.9 Å resolution, and the structure of Sco GlgEI-V279S complexed with 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM), an oxocarbenium mimic, was solved to 2.5 Å resolution. These structures detail important interactions that contribute to the inhibitory activity of these compounds, and provide information on future designs that may be exploited to improve upon these first generation GlgE inhibitors.

No MeSH data available.


Related in: MedlinePlus

α-1,4 glucan biosynthetic pathway, catalytic mechanism of GlgE, and current inhibitors of GlgE activity.(A) Biosynthetic pathway of the cytosolic α-1,4 glucan: trehalose is isomerized to maltose (TreS), which is subsequently phosphorylated (Pep2) to produce maltose-1-phosphate (M1P). M1P is used as the maltosyl donor in the generation of the liner glucan (GlgE) or branched α-1,6 glucan (GlgB). (B) GlgE mechanism. (1) Protonation by the general acid leads to the loss of phosphate and formation of the maltosyl enzyme intermediate. (3) Deprotonation of the 4-OH of the acceptor leads to the transfer of the maltose unit to the acceptor. (C) Structure and inhibitory data of a non-hydrolysable substrate analogue inhibitor of GlgE, α-maltose-C-phosphonate (MCP) next to the natural substrate α-maltose-1-phosphate (M1P) and (D) a transition-state mimic of GlgE, 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM) next to the oxocarbenium transition-state.
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f1: α-1,4 glucan biosynthetic pathway, catalytic mechanism of GlgE, and current inhibitors of GlgE activity.(A) Biosynthetic pathway of the cytosolic α-1,4 glucan: trehalose is isomerized to maltose (TreS), which is subsequently phosphorylated (Pep2) to produce maltose-1-phosphate (M1P). M1P is used as the maltosyl donor in the generation of the liner glucan (GlgE) or branched α-1,6 glucan (GlgB). (B) GlgE mechanism. (1) Protonation by the general acid leads to the loss of phosphate and formation of the maltosyl enzyme intermediate. (3) Deprotonation of the 4-OH of the acceptor leads to the transfer of the maltose unit to the acceptor. (C) Structure and inhibitory data of a non-hydrolysable substrate analogue inhibitor of GlgE, α-maltose-C-phosphonate (MCP) next to the natural substrate α-maltose-1-phosphate (M1P) and (D) a transition-state mimic of GlgE, 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM) next to the oxocarbenium transition-state.

Mentions: The glgE pathway of M. tb is one of three α-glucan biosynthetic pathways encoded by the M. tb genome6. This pathway produces a branched, cytosolic glucan using trehalose as a building block through the action of four different enzymes: TreS, Pep2, GlgE, and GlgB (Fig. 1A). GlgE is an α-maltose-1-phosphate:(1 → 4)-α-D-glucan-4-α-D-maltosyltransferase that catalyzes the addition of maltose to maltooligosaccharides (Fig. 1B). GlgE uses M1P to generate the α-1,4-glucan, while GlgB forms α-1,6 branches also using M1P as a substrate.


Crystal structures of Mycobacterium tuberculosis GlgE and complexes with non-covalent inhibitors.

Lindenberger JJ, Veleti SK, Wilson BN, Sucheck SJ, Ronning DR - Sci Rep (2015)

α-1,4 glucan biosynthetic pathway, catalytic mechanism of GlgE, and current inhibitors of GlgE activity.(A) Biosynthetic pathway of the cytosolic α-1,4 glucan: trehalose is isomerized to maltose (TreS), which is subsequently phosphorylated (Pep2) to produce maltose-1-phosphate (M1P). M1P is used as the maltosyl donor in the generation of the liner glucan (GlgE) or branched α-1,6 glucan (GlgB). (B) GlgE mechanism. (1) Protonation by the general acid leads to the loss of phosphate and formation of the maltosyl enzyme intermediate. (3) Deprotonation of the 4-OH of the acceptor leads to the transfer of the maltose unit to the acceptor. (C) Structure and inhibitory data of a non-hydrolysable substrate analogue inhibitor of GlgE, α-maltose-C-phosphonate (MCP) next to the natural substrate α-maltose-1-phosphate (M1P) and (D) a transition-state mimic of GlgE, 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM) next to the oxocarbenium transition-state.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526890&req=5

f1: α-1,4 glucan biosynthetic pathway, catalytic mechanism of GlgE, and current inhibitors of GlgE activity.(A) Biosynthetic pathway of the cytosolic α-1,4 glucan: trehalose is isomerized to maltose (TreS), which is subsequently phosphorylated (Pep2) to produce maltose-1-phosphate (M1P). M1P is used as the maltosyl donor in the generation of the liner glucan (GlgE) or branched α-1,6 glucan (GlgB). (B) GlgE mechanism. (1) Protonation by the general acid leads to the loss of phosphate and formation of the maltosyl enzyme intermediate. (3) Deprotonation of the 4-OH of the acceptor leads to the transfer of the maltose unit to the acceptor. (C) Structure and inhibitory data of a non-hydrolysable substrate analogue inhibitor of GlgE, α-maltose-C-phosphonate (MCP) next to the natural substrate α-maltose-1-phosphate (M1P) and (D) a transition-state mimic of GlgE, 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM) next to the oxocarbenium transition-state.
Mentions: The glgE pathway of M. tb is one of three α-glucan biosynthetic pathways encoded by the M. tb genome6. This pathway produces a branched, cytosolic glucan using trehalose as a building block through the action of four different enzymes: TreS, Pep2, GlgE, and GlgB (Fig. 1A). GlgE is an α-maltose-1-phosphate:(1 → 4)-α-D-glucan-4-α-D-maltosyltransferase that catalyzes the addition of maltose to maltooligosaccharides (Fig. 1B). GlgE uses M1P to generate the α-1,4-glucan, while GlgB forms α-1,6 branches also using M1P as a substrate.

Bottom Line: The maltohexaose structure reveals a dominant site for α-glucan binding.To obtain more detailed interactions between first generation, non-covalent inhibitors and GlgE, a variant Streptomyces coelicolor GlgEI (Sco GlgEI-V279S) was made to better emulate the Mtb GlgE M1P binding site.These structures detail important interactions that contribute to the inhibitory activity of these compounds, and provide information on future designs that may be exploited to improve upon these first generation GlgE inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Biochemistry, The University of Toledo, 2801 W. Bancroft St. Ms602, Toledo, OH, United States.

ABSTRACT
GlgE is a bacterial maltosyltransferase that catalyzes the elongation of a cytosolic, branched α-glucan. In Mycobacterium tuberculosis (M. tb), inactivation of GlgE (Mtb GlgE) results in the rapid death of the organism due to a toxic accumulation of the maltosyl donor, maltose-1-phosphate (M1P), suggesting that GlgE is an intriguing target for inhibitor design. In this study, the crystal structures of the Mtb GlgE in a binary complex with maltose and a ternary complex with maltose and a maltosyl-acceptor molecule, maltohexaose, were solved to 3.3 Å and 4.0 Å, respectively. The maltohexaose structure reveals a dominant site for α-glucan binding. To obtain more detailed interactions between first generation, non-covalent inhibitors and GlgE, a variant Streptomyces coelicolor GlgEI (Sco GlgEI-V279S) was made to better emulate the Mtb GlgE M1P binding site. The structure of Sco GlgEI-V279S complexed with α-maltose-C-phosphonate (MCP), a non-hydrolyzable substrate analogue, was solved to 1.9 Å resolution, and the structure of Sco GlgEI-V279S complexed with 2,5-dideoxy-3-O-α-D-glucopyranosyl-2,5-imino-D-mannitol (DDGIM), an oxocarbenium mimic, was solved to 2.5 Å resolution. These structures detail important interactions that contribute to the inhibitory activity of these compounds, and provide information on future designs that may be exploited to improve upon these first generation GlgE inhibitors.

No MeSH data available.


Related in: MedlinePlus