Thiamin phosphate kinase

The hypE proteins are 302-376 residues long and appear to consist of three domains. Domain 1 shows sequence identity to a domain from phosphoribosyl-aminoimida-zole synthetase which is involved in the fifth step in de novo purine biosynthesis and to a domain in thiamine phosphate kinase which is involved in the synthesis of the cofactor thiamine diphosphate (TDP). TDP is required by enzymes which cleave the bond adjacent to carbonyl groups, e.g. phosphoketolase, transketolase or pyruvate decarboxylase. Domain 2 also shows identity to a domain found in thiamine phosphate kinase. Domain 3 appears to be unique to the HypF proteins. 

HMP-P kinase (ThiD) and thiamin phosphate kinase (ThiL) have been hiochemically and structurally characterized (Figure 10. Both follow the expected in-line mechanism for phosphate transfer from... 

The coupling reaction between THZ-P and HMP-PP, mediated by ThiE, generates ThMP. The latter is converted to ThDP, the active form of the cofactor, by a thiamin phosphate kinase (ThiL) (Figure 5.92). ThDP can also be formed in one step from thiamin using thiamin pyrophosphokinase. In bacteria, this enzyme is called ThiN. In higher organisms, the thiamin pyrophosphokinase is named THI80. 

In those organisms able to synthesize thiamin, the endpoint of synthesis is ThMP. In enterobacteria, such as E. coli, ThMP can then be phosphorylated to ThDP by thiamin phosphate kinase (EC 2.7.4.16). Thiamin taken up from the extracellular medium is first phosphorylated to ThMP by thiamin kinase (EC 2.7.1.89). In thiamin-synthesizing eukaryotes such as fungi and plants, ThMP is dephosphorylated to thiamin by phosphatases. Thiamin is then pyropho-sphorylated to ThDP by TPK. 

In animals, ThDP is formed from thiamin by a thiamin pyropho-sphokinase and, in enterobacteria, from thiamin monophosphate by a thiamin phosphate kinase. 

S ATP + 2-methyl-4-amino-5-pho.sphomethylpyrimidine <1, 2, 3> (<1> specific for ATP [1] <3> enzyme has both 2-methyl-4-amino-5-hydroxy-methylpyrimidine phosphate kinase and thiamin-phosphate diphosphatase activities, involved in thiamine biosynthesis [3]) (Reversibility <1, 2, 3> [1,2, 3]) [1,2,3]... 

Reddick, J.J. Kinsland, C. Nicewonger, R. Christian, T Downs, D.M. Winkler, M.E. Begley, T.P. Overexpression, purification and characterization of two pyrimidine kinases involved in the biosynthesis of thiamin 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase and 4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate kinase. Tetrahedron, 54, 15983-15991 (1998)... 

ATP thiamin-phosphate phosphotransferase kinase, thiamin monophosphate (phosphorylating) thiamin monophosphatase... 

Thiamin is synthesized in bacteria, fungi, and plants from 1-deoxyxylulose 5-phosphate (Eq. 25-21), which is also an intermediate in the nonmevalonate pathway of polyprenyl synthesis. However, thiamin diphosphate is a coenzyme for synthesis of this intermediate (p. 736), suggesting that an alternative pathway must also exist. Each of the two rings of thiamin is formed separately as the esters 4-amino-5-hydroxy-methylpyrimidine diphosphate and 4-methyl-5-((i-hydroxyethyl) thiazole monophosphate. These precursors are joined with displacement of pyrophosphate to form thiamin monophosphate.92b In eukaryotes this is hydrolyzed to thiamin, then converted to thiamin diphosphate by transfer of a diphospho group from ATP.92b c In bacteria thiamin monophosphate is converted to the diphosphate by ATP and thiamin monophosphate kinase.92b... 

Thiamine is synthesized biologically from the pyrimidine derivative 4-amino-5-hydroxymethyl-2-mcthyl pyrimidine methylpyrimidine and 5-( hydtoxycthyl)-4-methylthia-zole. These two precursors are converted to phosphate derivatives under kinase catalysis, which requires ATP. The respective phosphate derivatives then interact to form thiamine phosphate in a reaction catalyzed by thiamine phosphate pyr-ophosphotyla.se. 

Vitamin Bi is an essential co-factor for several enzymes of carbohydrate metabolism such as transketolase, pyruvate dehydrogenase (PDH), pyruvate decarboxylase and a-ketoglutarate dehydrogenase. To become the active co-factor thiamin pyrophosphate (TPP), thiamin has to be salvaged by thiamin pyrophosphokinase or synthesized de novo. In Escherichia coli and Saccharomyces cerevisiae thiamin biosynthesis proceeds via two branches that have to be combined. In the pyrimidine branch, 4-amino-5-hydroxymethy-2-methylpyrimidine (PIMP) is phosphorylated to 4-amino-2-methyl-5-hydroxymethyl pyrimidine diphosphate (PIMP-PP) by the enzyme HMP/HMP-P kinase (ThiD) however, the step can also be catalyzed by pyridoxine kinase (PdxK), an enzyme also responsible for the activation of vitamin B6 (see below). The second precursor of thiamin biosynthesis, 5-(2-hydroxyethyl)-4-methylthiazole (THZ), is activated by THZ kinase (ThiM) to 4-methyl-5-(2-phosphoethyl)-thiazole (THZ-P), and then the thia-zole and pyrimidine moieties, HMP-PP and THZ-P, are combined to form thiamin phosphate (ThiP) by thiamin phosphate synthase (ThiE). The final step, pyrophosphorylation, yields TPP and is carried out by thiamin pyrophosphorylase (TPK). 

S Additional information <2, 4> (<4> enzyme is probably different from previously isolated HMP kinase, because the subunit molecular masses are significantly different [4] <4> bifunctional hydroxymethylpyrimidine kinase/phosphomethylpyrimidine kinase [5] <2> bifunctional hydroxy-pyrimidine kinase/thiamin-phosphate pyrophosphorylase [3]) [3-5]... 

Kim, Y.S. Nosaka, K. Downs, D.M. Kwak, J.M. Park, D. Chung, I.K. Nam, H.G. A Brassica cDNA clone encoding a bifunctional hydroxymethylpyrimidine kinase/thiamin-phosphate pyrophosphorylase involved in thiamin biosynthesis. Plant Mol. Biol., 37, 955-966 (1998)... 

Saccharomyces cerevisiae (mutant resistant to 2-amino-4-methyl-5- -hy-droxyethylthiazole, an antimetabolite of 4-methyl-5-/l-hydroxyethylthia-zole, deficient in activity of both EC 2.5.1.3 and EC 2.7.1.50 [2] bifunctional enzyme with hydroxyethylthiazole kinase and thiamine-phosphate pyrophosphorylase activity [2]) [1, 2]... 

Kawasaki, Y. Copurification of hydroxyethylthiazole kinase and thiamine-phosphate pyrophosphorylase of Saccharomyces cerevisiae characterization of hydroxyethylthiazole kinase as a bifunctional enzyme in the thiamine biosynthetic pathway. J. Bacteriol., 175, 5153-5158 (1993)... 

In humans, thiamine is both actively and passively absorbed to a limited level in the intestines, is transported as the free vitamin, is then taken up in actively metabolizing tissues, and is converted to the phosphate esters via ubiquitous thiamine kinases. During thiamine deficiency all tissues stores are readily mobilhed. Because depletion of thiamine levels in erythrocytes parallels that of other tissues, erythrocyte thiamine levels ate used to quantitate severity of the deficiency. As deficiency progresses, thiamine becomes indetectable in the urine, the primary excretory route for this vitamin and its metaboHtes. Six major metaboHtes, of more than 20 total, have been characterized from human urine, including thiamine fragments (7,8), and the corresponding carboxyHc acids (1,37,38). 

Biosynthesis of pyrophosphate (5) from pyrimidine phosphate (47) and thia2ole phosphate (48) depends on the activity of five en2ymes, four of them kinases (87). In yeasts and many other organisms, including humans, pyrophosphate (5) can be obtained from exogenous thiamine in a single step cataly2ed by thiamine pyrophosphokinase (88). 

The following are topics that may be especially valuable to the student and which might be read initially in Chapter 12, lysozyme (Section B,5), chymo-trypsin (Section C,l), kinases (Section D,9), multiple displacement, reactions (Section G) in Chapter 13, imines (Section A,2), addition to C=C bonds (Section A, 4,5), beta cleavage and condensation (Section C) in Chapter 14, thiamin diphosphate (Section D), pyridoxal phosphate (Section E) in Chapter 15, NAD (Section A). 

Nghiem HO, Bettendorff L, and Changeux JP (2000) Specific phosphorylation ofTorpedo 43K rapsyn by endogenous kinase(s) with thiamine triphosphate as the phosphate donor. FASEB Journal 14, 543-54. 

The three tissue enzymes known to participate in formation of the phosphate esters are (1) thiaminokinase (a pyro-phosphokinase), which catalyzes formation of TPP and adenosine monophosphate (AMP) from thiamine and adenosine triphosphate (ATP) (2) TPP-ATP phosphoryl-transferase (cytosoHc 5"-adenylic kinase)which forms the triphosphate and adenosine diphosphate from TPP and ATP and (3) thiamine triphosphatase, which hydrolyzes TPP to the monophosphate. Although thiaminokinase is widespread, the phosphoryl transferase and membrane-associated triphosphatase are mainly in nervous tissue. 

Park, J.H. et al. (2004) Characterization of two kinases involved in thiamine pyrophosphate and pyridoxal phosphate biosynthesis in Bacillus subtilis 4-amino-5-hydroxymethyl-2-methylpyrimidine kinase and pyridoxal kinase. J. Bacterial, 186... 

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