Characterization of a tetrameric inositol monophosphatase from the hyperthermophilic bacterium Thermotoga maritima

Journal Article · Fri Oct 01 04:00:00 EDT 1999 · Applied and Environmental Microbiology

OSTI ID:20001035

Chen, L; Roberts, M F

Inositol monophosphatase (I-1-Pase) catalyzes the dephosphorylation step in the de novo biosynthetic pathway of inositol and is crucial for all inositol-dependent processes. An extremely heat-stable tetrameric form of I-1-Pase from the hyperthermophilic bacterium Thermotoga maritima was overexpressed in Escherichia coli. In addition to its different quaternary structure, this enzyme displayed a 20-fold higher rate of hydrolysis of D-inositol 1-phosphate than of the L isomer. The homogeneous recombinant T. maritima I-1-Pase possessed an unusually high V{sub max} that was much higher than the V{sub max} of the same enzyme from another hyperthermophile, Methanococcus jannaschii. Although T. maritima is a eubacterium, its I-1-Pase is more similar to archaeal I-1-Pases than to the other known bacterial or mammalian I-1-Pases with respect to substrate specificity, Li{sup +} inhibition, inhibition by high Mg{sup 2+} concentrations, metal ion activation, heat stability, and activation energy. Possible reasons for the observed kinetic differences are discussed based on an active site sequence alignment of the human and T. maritima I-1-Pases.

• Research Organization: Boston Coll., Chestnut Hill, MA (US)
• Sponsoring Organization: US Department of Energy; National Science Foundation
• DOE Contract Number: FG02-91ER20025
• OSTI ID: 20001035
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 10 Vol. 65; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
BACTERIA
BIOLOGICAL PATHWAYS
INOSITOL
MOLECULAR STRUCTURE
PHOSPHATASES