Distribution of folates and modified folates in extremely thermophilic bacteria

Abstract

Analyses were made of the structures and levels of folates and modified folates present in extremely thermophilic bacteria. These procedures involved the chemical analysis of products resulting from the oxidative cleavage of the 6-substituted, folatelike tetrahydropterins present in the cells. Air-oxidized cell extracts of extreme thermophiles from two members of the archaebacterial order Thermococcales, Thermococcus celer and Pyrococcusfuriosus, contained only 7-methylpterin, indicating that these cells contain a modified folate with a methylated pterin. Cell extracts also contained 6-acetyl-7-methyl-7,8-dihydropterin, another product derived from the oxidative cleavage of a dimethylated folate, demonstrating that both the C-7 and C-9 carbons of the pterin were methylated. Extracts, however, contained neither p-aminobenzoylpolyglutamates nor methaniline, the oxidative cleavage products of folates and methanopterin, respectively, indicating that they contain a previously undescribed C1 carrier(s). On the basis of the level of the 7-methylpterin isolated, the levels of modified folate were 2 to 10 times higher than those typically found in mesophilic bacteria and 10 to 100 times less than the levels of methanopterin found in the methanogenic bacteria. Oxidized cell extracts of Sulfolobus spp. of the archaebacterial order Sulfolobaks contained only pterin, and, like members of the order Thermococcales, they contained neither p-aminobenzoylpolyglutamates nor methaniline. Oxidized cell extracts of the extreme thermophiles Pyrobaculum sp. strain H10 and Pyrodictium occultum, from the archaebacterial orders Thermoproteales and Pyrodictiales, respectively, and Thermotoga maritima, from the eubacterial order Thermotogales, contained pterin and p-aminobenzoylpolyglutamates, indicating that these cells contained unmodified folates. The levels of p-aminobenzoylpolyglutamates in these archaebacterial cell extracts indicate that the folates were present in the cells at levels 4 to 10 times higher than generally found in those mesophilic eubacteria which do not use folates in energy metabolism. The levels and chain lengths of the of p-aminobenzoylpolyglutamates present in Thermotoga maritima were typical of those found in mesophilic eubacteria.Folic acid and its polyglutamyl derivatives represent one of the central coenzymes found in biological systems where folic acid functions as a C1 carrier. The core of the folate coenzyme structures was established in 1946 (1), and no modifications of this original structure were found until 1980 when the first structurally modified folate, methanopterin, was characterized (25,26). Methanopterin was isolated and characterized because of its involvement as a C1 carrier in the reduction of CO2 to CH4 in methanogenic archaebacteria where it functions analogously to folate (21). (The close similarity between the biosynthesis of folate and the biosynthesis of methanopterin further supports the close connection between these C1 carriers [27,29,30,33].) Subsequent work has indicated that thi...

Catalytic and Thermodynamic Properties of Tetrahydromethanopterin-dependent Serine Hydroxymethyltransferase from Methanococcus jannaschii

“…In the first report, the enzyme was proposed to function in vivo in the direction of serine biosynthesis. Importantly, both works provided evidence that SHMT was selective toward the modified folate used by the source organisms: H 4 MPT for M. marburgensis and sulfopterin for S. solfataricus (2,7).…”

Structures of the modified folates in the extremely thermophilic archaebacterium Thermococcus litoralis

“…These values are comparable to the amount of modified folates in P. furiosus (33.7 nmol/g [dry weight] of cells). These values are about 10 times higher than the amount of folate in eubacteria and 100 times less that the amount of methanopterin present in the methanogens (5).…”

“…Recent work on the analysis of the modified folates present in thermophilic archaea has shown that species from both genera of the order Thermococcales (i.e., Pyrococcus and Thermococcus) contain different modified folates (5). Structural characterization of the modified folates in Pyrococcus furosus show them to consist of the three similar structures shown in Fig.…”

Moonlighting Glutamate Formiminotransferases Can Functionally Replace 5-Formyltetrahydrofolate Cycloligase

“…The capacity to form 5-CHO-THF is thus also almost universal, and consequently so is the need for 5-CHO-THF removal. It might therefore be expected that all organisms would have 5-FCL, except those few that lack SHMT (14) or folates (15). However, in the course of a comparative genomic analysis of folate synthesis and metabolism involving hundreds of genomes (16) we were surprised to note that diverse prokaryotes had genes encoding SHMT (glyA) and other folate-dependent enzymes but no gene for .…”

“…A, distribution among representative prokaryotes of the FT gene, of other histidine degradation genes (hutHUI, hutG, forI, nfoD, CD), and of the genes involved in 5-CHO-THF formation (glyA) and removal (ygfA). The tree shows the standard branching order for each group and is adapted from (60), with the addition of archaea (61) for which chemical, biochemical, or genomic evidence supports the presence of folates (15,16,62,63). Note the anticorrelated distributions of ygfA and FT. Organisms whose FTs were tested experimentally are highlighted in yellow.…”