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Mycobacterium tuberculosis IMPDH in Complexes with Substrates, Products and Antitubercular Compounds.

Makowska-Grzyska M, Kim Y, Gorla SK, Wei Y, Mandapati K, Zhang M, Maltseva N, Modi G, Boshoff HI, Gu M, Aldrich C, Cuny GD, Hedstrom L, Joachimiak A - PLoS ONE (2015)

Bottom Line: The enzyme catalyzes the conversion of inosine 5'-monophosphate into xanthosine 5'-monophosphate with the concomitant reduction of NAD+ to NADH.The crystal structures of a deletion mutant of MtbIMPDH2 in the apo form and in complex with the product XMP and substrate NAD+ are determined.These structures will greatly facilitate the development of MtbIMPDH2-targeted antibiotics.

View Article: PubMed Central - PubMed

Affiliation: Center for Structural Genomics of Infectious Diseases, University of Chicago, Chicago, IL, United States of America.

ABSTRACT
Tuberculosis (TB) remains a worldwide problem and the need for new drugs is increasingly more urgent with the emergence of multidrug- and extensively-drug resistant TB. Inosine 5'-monophosphate dehydrogenase 2 (IMPDH2) from Mycobacterium tuberculosis (Mtb) is an attractive drug target. The enzyme catalyzes the conversion of inosine 5'-monophosphate into xanthosine 5'-monophosphate with the concomitant reduction of NAD+ to NADH. This reaction controls flux into the guanine nucleotide pool. We report seventeen selective IMPDH inhibitors with antitubercular activity. The crystal structures of a deletion mutant of MtbIMPDH2 in the apo form and in complex with the product XMP and substrate NAD+ are determined. We also report the structures of complexes with IMP and three structurally distinct inhibitors, including two with antitubercular activity. These structures will greatly facilitate the development of MtbIMPDH2-targeted antibiotics.

No MeSH data available.


Related in: MedlinePlus

Mechanism and inhibitors of MtbIMPDH2.(A) Reactions catalyzed by IMPDH. MtbIMPDH2 numbering is shown. (B) The anti- and syn- conformations of nicotinamide ring in NADH. (C) CpIMPDH inhibitors, for which crystal structures of MtbIMPDH2•IMP•I were obtained. Portions of inhibitors that bind in the nicotinamide-subsite (left side) and the AB-subsite (right side) are indicated. Stereochemistry is denoted where applicable. NAD+ is shown for comparison.
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pone.0138976.g001: Mechanism and inhibitors of MtbIMPDH2.(A) Reactions catalyzed by IMPDH. MtbIMPDH2 numbering is shown. (B) The anti- and syn- conformations of nicotinamide ring in NADH. (C) CpIMPDH inhibitors, for which crystal structures of MtbIMPDH2•IMP•I were obtained. Portions of inhibitors that bind in the nicotinamide-subsite (left side) and the AB-subsite (right side) are indicated. Stereochemistry is denoted where applicable. NAD+ is shown for comparison.

Mentions: The enzymatic mechanism of IMPDH has been extensively studied and consists two steps, a dehydrogenase and a hydrolase reaction (Fig 1A) [10,18]. Upon binding of IMP and NAD+ cofactor, a thioimidate enzyme-substrate adduct, E-XMP*, is formed via a covalent bond to the catalytic C341 (MtbIMPDH2 numbering) with concurrent production of NADH. Hydride transfer occurs to the pro-S position with the cofactor in the anti-conformation (Fig 1B). The cofactor is released and an active site mobile flap moves into the NAD+ site and facilitates E-XMP* hydrolysis with a conserved R443 acting as a general base. Thus, the enzyme has two distinct conformations, an open form for the dehydrogenase reaction and a closed form for E-XMP* hydrolysis. IMPDH has multiple active site states (apoE, E•IMP, E•IMP•NAD+, E-XMP*•NADH adduct) that can be targeted for inhibitor design, and both the IMP/XMP and cofactor binding sites have been exploited for that purpose [10,18,19].


Mycobacterium tuberculosis IMPDH in Complexes with Substrates, Products and Antitubercular Compounds.

Makowska-Grzyska M, Kim Y, Gorla SK, Wei Y, Mandapati K, Zhang M, Maltseva N, Modi G, Boshoff HI, Gu M, Aldrich C, Cuny GD, Hedstrom L, Joachimiak A - PLoS ONE (2015)

Mechanism and inhibitors of MtbIMPDH2.(A) Reactions catalyzed by IMPDH. MtbIMPDH2 numbering is shown. (B) The anti- and syn- conformations of nicotinamide ring in NADH. (C) CpIMPDH inhibitors, for which crystal structures of MtbIMPDH2•IMP•I were obtained. Portions of inhibitors that bind in the nicotinamide-subsite (left side) and the AB-subsite (right side) are indicated. Stereochemistry is denoted where applicable. NAD+ is shown for comparison.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594927&req=5

pone.0138976.g001: Mechanism and inhibitors of MtbIMPDH2.(A) Reactions catalyzed by IMPDH. MtbIMPDH2 numbering is shown. (B) The anti- and syn- conformations of nicotinamide ring in NADH. (C) CpIMPDH inhibitors, for which crystal structures of MtbIMPDH2•IMP•I were obtained. Portions of inhibitors that bind in the nicotinamide-subsite (left side) and the AB-subsite (right side) are indicated. Stereochemistry is denoted where applicable. NAD+ is shown for comparison.
Mentions: The enzymatic mechanism of IMPDH has been extensively studied and consists two steps, a dehydrogenase and a hydrolase reaction (Fig 1A) [10,18]. Upon binding of IMP and NAD+ cofactor, a thioimidate enzyme-substrate adduct, E-XMP*, is formed via a covalent bond to the catalytic C341 (MtbIMPDH2 numbering) with concurrent production of NADH. Hydride transfer occurs to the pro-S position with the cofactor in the anti-conformation (Fig 1B). The cofactor is released and an active site mobile flap moves into the NAD+ site and facilitates E-XMP* hydrolysis with a conserved R443 acting as a general base. Thus, the enzyme has two distinct conformations, an open form for the dehydrogenase reaction and a closed form for E-XMP* hydrolysis. IMPDH has multiple active site states (apoE, E•IMP, E•IMP•NAD+, E-XMP*•NADH adduct) that can be targeted for inhibitor design, and both the IMP/XMP and cofactor binding sites have been exploited for that purpose [10,18,19].

Bottom Line: The enzyme catalyzes the conversion of inosine 5'-monophosphate into xanthosine 5'-monophosphate with the concomitant reduction of NAD+ to NADH.The crystal structures of a deletion mutant of MtbIMPDH2 in the apo form and in complex with the product XMP and substrate NAD+ are determined.These structures will greatly facilitate the development of MtbIMPDH2-targeted antibiotics.

View Article: PubMed Central - PubMed

Affiliation: Center for Structural Genomics of Infectious Diseases, University of Chicago, Chicago, IL, United States of America.

ABSTRACT
Tuberculosis (TB) remains a worldwide problem and the need for new drugs is increasingly more urgent with the emergence of multidrug- and extensively-drug resistant TB. Inosine 5'-monophosphate dehydrogenase 2 (IMPDH2) from Mycobacterium tuberculosis (Mtb) is an attractive drug target. The enzyme catalyzes the conversion of inosine 5'-monophosphate into xanthosine 5'-monophosphate with the concomitant reduction of NAD+ to NADH. This reaction controls flux into the guanine nucleotide pool. We report seventeen selective IMPDH inhibitors with antitubercular activity. The crystal structures of a deletion mutant of MtbIMPDH2 in the apo form and in complex with the product XMP and substrate NAD+ are determined. We also report the structures of complexes with IMP and three structurally distinct inhibitors, including two with antitubercular activity. These structures will greatly facilitate the development of MtbIMPDH2-targeted antibiotics.

No MeSH data available.


Related in: MedlinePlus