Crystal structure of a major fragment of the salt-tolerant glutaminase from Micrococcus luteus K-3.

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Yoshimune K, Shirakihara Y, Shiratori A, Wakayama M, Chantawannakul P, Moriguchi M

Crystal structure of a major fragment of the salt-tolerant glutaminase from Micrococcus luteus K-3.

Biochem Biophys Res Commun. 2006 Aug 11;346(4):1118-24. Epub 2006 Jun 6.

PubMed ID

16793004 [ View in PubMed

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Abstract

Glutaminase of Micrococcus luteus K-3 (intact glutaminase; 48kDa) is digested to a C-terminally truncated fragment (glutaminase fragment; 42kDa) that shows higher salt tolerance than that of the intact glutaminase. The crystal structure of the glutaminase fragment was determined at 2.4A resolution using multiple-wavelength anomalous dispersion (MAD). The glutaminase fragment is composed of N-terminal and C-terminal domains, and a putative catalytic serine-lysine dyad (S64 and K67) is located in a cleft of the N-terminal domain. Mutations of the S64 or K67 residues abolished the enzyme activity. The N-terminal domain has abundant glutamic acid residues on its surface, which may explain its salt-tolerant mechanism. A diffraction analysis of the intact glutaminase crystals (a twinning fraction of 0.43) located the glutaminase fragment in the unit cell but failed to turn up clear densities for the missing C-terminal portion of the molecule.

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Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Glutamic acid	Glutaminase liver isoform, mitochondrial	Protein	Humans	Unknown	Not Available	Details