An Uncharacterized Member of the Ribokinase Family in Thermococcus kodakarensis Exhibits myo-Inositol Kinase Activity

Abstract

Background:The archaeon Thermococcus kodakarensis harbors an uncharacterized member of the ribokinase family encoded by TK2285. Results: The structure of the TK2285 protein was elucidated, and the protein exhibited unexpected kinase activity toward myo-inositol. Conclusion:The Thermococcales harbor a novel, archaea-type ribokinase family member with activity toward myo-inositol. Significance: Our results raise the possibility of a novel mechanism of inositol metabolism in Archaea.

Perdeuterated and 13C-enriched myo-inositol for DNP assisted monitoring of enzymatic phosphorylation by inositol-3-kinase

“…This can be compared to values in the literature of 44 μmol min -1 mg -1 . 29 This is reasonable agreement considering that our measurements are at approximately 30°C as compare to 85°C for literature data; Thermococcus kodakarensis is a hyperthermophile and may have enhanced activity at higher temperatures.…”

“…26, 27 In some archaea and plants enzymatic phosphorylation at the 3 position of soluble myo-inositol also occurs. 28, 29 Interestingly, small peptides have been found to catalyse similar stereo-specific phosphorylation. 30 Here, we use the TK2285 gene product from Thermococcus kodakarensis (myo-inositol- 3-kinase, EC 2.7.1.64) as an easily accessible system to illustrate the spectral changes that occur on phosphorylation of inositol containing substrates, and the advantages of DNP-enhanced NMR.…”

Crystal Structure and Product Analysis of an Archaeal myo-Inositol Kinase Reveal Substrate Recognition Mode and 3-OH Phosphorylation

“…2,4 Two characteristic features of ribokinases around the ligand-binding site are also observed in the TK2285 protein. 4 The first one is a glycine-rich motif, which induces a lid domain motion to close the active site via substrate binding. The other is the catalytic aspartate, which is thought to activate the hydroxyl group of the phosphate acceptor and corresponds to D219 in TK2285.…”

“…4 We have reported the prominent phosphorylation activity of this enzyme toward myo-inositol. 4 To date, only two myo-inositol kinases have been identified. One is the TK2285, and the other is Lpa3 from a crop plant, Zea mays.…”

Crystallization and preliminary X-ray analysis of a ribokinase fromVibrio choleraeO395

“…The structure and catalytic mechanism of human RK (Park et al, 2007) are very similar to those of E. coli RK. Recently, crystal structures of Sa239, an RK from Staphylococcus aureus (Li et al, 2012), and of an RK homologue from Thermococcus kodakarensis (Sato et al, 2013) (Chuvikovsky et al, 2006;Park & Gupta, 2008), whereas monovalent cations such as Na + , K + , Cs + and NH 4 + serve as an activator of RK (Andersson & Mowbray, 2002;Chuvikovsky et al, 2006). Large relative motion between the domains in the same subunit upon substrate binding is thought to be responsible for the entry and release of ribose.…”