Structural basis for the catalysis and substrate specificity of homoserine kinase

S. S. Krishna, T. Zhou, M. Daugherty, A. Osterman, H. Zhang

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Homoserine kinase (HSK), the fourth enzyme in the aspartate pathway of amino acid biosynthesis, catalyzes me pnosphorylanon of L-homoserine (Hse) to L-homoserine phosphate, an intermediate in the production of L-threonine, L-isoleucine, and in higher plants, L-methionine. The high-resolution structures of Methanococcus jannaschii HSK ternary complexes with its amino acid substrate and ATP analogues have been determined by X-ray crystallography. These structures reveal the structural determinants of the tight and highly specific binding of Hse, which is coupled with local conformational changes that enforce the sequestration of the substrate. The δ-hydroxyl group of bound Hse is only 3.4 Å away from the γ-phosphate of the bound nucleotide, poised for the in-line attack at the γ-phosphorus. The bound nucleotides are flexible at the triphosphate tail. Nevertheless, a Mg2+ was located in one of the complexes that binds between the β- and γ-phosphates of the nucleotide with good ligand geometry and is coordinated by the side chain of Glu130. No strong nucleophile (base) can be located near the phosphoryl acceptor hydroxyl group. Therefore, we propose that the catalytic mechanism of HSK does not involve a catalytic base for activating the phosphoryl acceptor hydroxyl but instead is mediated via a transition state stabilization mechanism.

Original languageEnglish (US)
Pages (from-to)10810-10818
Number of pages9
JournalBiochemistry
Volume40
Issue number36
DOIs
StatePublished - Sep 11 2001

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homoserine kinase
Homoserine
Substrate Specificity
Catalysis
Hydroxyl Radical
Nucleotides
Substrates
Methanocaldococcus
Phosphates
Amino Acids
Nucleophiles
Isoleucine
X ray crystallography
X Ray Crystallography
Biosynthesis
Threonine
Aspartic Acid
Methionine
Phosphorus
Stabilization

ASJC Scopus subject areas

  • Biochemistry

Cite this

Krishna, S. S., Zhou, T., Daugherty, M., Osterman, A., & Zhang, H. (2001). Structural basis for the catalysis and substrate specificity of homoserine kinase. Biochemistry, 40(36), 10810-10818. https://doi.org/10.1021/bi010851z

Structural basis for the catalysis and substrate specificity of homoserine kinase. / Krishna, S. S.; Zhou, T.; Daugherty, M.; Osterman, A.; Zhang, H.

In: Biochemistry, Vol. 40, No. 36, 11.09.2001, p. 10810-10818.

Research output: Contribution to journalArticle

Krishna, SS, Zhou, T, Daugherty, M, Osterman, A & Zhang, H 2001, 'Structural basis for the catalysis and substrate specificity of homoserine kinase', Biochemistry, vol. 40, no. 36, pp. 10810-10818. https://doi.org/10.1021/bi010851z
Krishna SS, Zhou T, Daugherty M, Osterman A, Zhang H. Structural basis for the catalysis and substrate specificity of homoserine kinase. Biochemistry. 2001 Sep 11;40(36):10810-10818. https://doi.org/10.1021/bi010851z
Krishna, S. S. ; Zhou, T. ; Daugherty, M. ; Osterman, A. ; Zhang, H. / Structural basis for the catalysis and substrate specificity of homoserine kinase. In: Biochemistry. 2001 ; Vol. 40, No. 36. pp. 10810-10818.
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