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Structural characterization of inhibitors with selectivity against members of a homologous enzyme family.

ABSTRACT: The aspartate biosynthetic pathway provides essential metabolites for many important biological functions, including the production of four essential amino acids. As this critical pathway is only present in plants and microbes, any disruptions will be fatal to these organisms. An early pathway enzyme, l-aspartate-?-semialdehyde dehydrogenase, produces a key intermediate at the first branch point of this pathway. Developing potent and selective inhibitors against several orthologs in the l-aspartate-?-semialdehyde dehydrogenase family can serve as lead compounds for antibiotic development. Kinetic studies of two small molecule fragment libraries have identified inhibitors that show good selectivity against l-aspartate-?-semialdehyde dehydrogenases from two different bacterial species, Streptococcus pneumoniae and Vibrio cholerae, despite the presence of an identical constellation of active site amino acids in this homologous enzyme family. Structural characterization of enzyme-inhibitor complexes have elucidated different modes of binding between these structurally related enzymes. This information provides the basis for a structure-guided approach to the development of more potent and more selective inhibitors.

SUBMITTER: Pavlovsky AG

PROVIDER: S-EPMC3383612 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Structural characterization of inhibitors with selectivity against members of a homologous enzyme family.

Pavlovsky Alexander G AG Liu Xuying X Faehnle Christopher R CR Potente Nina N Viola Ronald E RE

Chemical biology & drug design 20111128 1

The aspartate biosynthetic pathway provides essential metabolites for many important biological functions, including the production of four essential amino acids. As this critical pathway is only present in plants and microbes, any disruptions will be fatal to these organisms. An early pathway enzyme, l-aspartate-β-semialdehyde dehydrogenase, produces a key intermediate at the first branch point of this pathway. Developing potent and selective inhibitors against several orthologs in the l-aspart ...[more]

PMID: 22039970

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Project description:The tautomerase superfamily consists of structurally homologous proteins that are characterized by a ?-?-? fold and a catalytic amino-terminal proline. 4-Oxalocrotonate tautomerase (4-OT) family members have been identified and categorized into five subfamilies on the basis of multiple sequence alignments and the conservation of key catalytic and structural residues. Representative members from two subfamilies have been cloned, expressed, purified, and subjected to kinetic and structural characterization. The crystal structure of DmpI from Helicobacter pylori (HpDmpI), a 4-OT homolog in subfamily 3, has been determined to high resolution (1.8Å and 2.1Å) in two different space groups. HpDmpI is a homohexamer with an active site cavity that includes Pro-1, but lacks the equivalent of Arg-11 and Arg-39 found in 4-OT. Instead, the side chain of Lys-36 replaces that of Arg-11 in a manner similar to that observed in the trimeric macrophage migration inhibitory factor (MIF), which is the title protein of another family in the superfamily. The electrostatic surface of the active site is also quite different and suggests that HpDmpI might prefer small, monoacid substrates. A kinetic analysis of the enzyme is consistent with the structural analysis, but a biological role for the enzyme remains elusive. The crystal structure of DmpI from Archaeoglobus fulgidus (AfDmpI), a 4-OT homolog in subfamily-4, has been determined to 2.4Å resolution. AfDmpI is also a homohexamer, with a proposed active site cavity that includes Pro-1, but lacks any other residues that are readily identified as catalytic ones related to 4-OT activity. Indeed, the electrostatic potential of the active site differs significantly in that it is mostly neutral, in contrast to the usual electropositive features found in other 4-OT family members, suggesting that AfDmpI might accommodate hydrophobic substrates. A kinetic analysis has been carried out, but does not provide any clues about the type of reaction the enzyme might catalyze.

Dataset Information

Structural characterization of inhibitors with selectivity against members of a homologous enzyme family.

Publications

Structural characterization of inhibitors with selectivity against members of a homologous enzyme family.

Similar Datasets

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