Menaquinone-Specific Prenyl Reductase from the Hyperthermophilic Archaeon Archaeoglobus fulgidus

Abstract

Four genes that encode the homologues of plant geranylgeranyl reductase were isolated from a hyperthermophilic archaeon Archaeoglobus fulgidus, which produces menaquinone with a fully saturated heptaprenyl side chain, menaquinone-7(14H). The recombinant expression of one of the homologues in Escherichia coli led to a distinct change in the quinone profile of the host cells, although the homologue is the most distantly related to the geranylgeranyl reductase. The new compounds found in the profile had successively longer elution times than those of ordinary quinones from E. coli, i.e., menaquinone-8 and ubiquinone-8, in high-performance liquid chromatography on a reversed-phase column. Structural analyses of the new compounds by electron impactmass spectrometry indicated that their molecular masses progressively increase relative to the ordinary quinones at a rate of 2 U but that they still contain quinone head structures, strongly suggesting that the compounds are quinones with partially saturated prenyl side chains. In vitro assays with dithionite as the reducing agent showed that the prenyl reductase is highly specific for menaquinone-7, rather than ubiquinone-8 and prenyl diphosphates. This novel enzyme noncovalently binds flavin adenine dinucleotide, similar to geranylgeranyl reductase, but was not able to utilize NAD(P)H as the electron donor, unlike the plant homologue.

Identification of the bchP Gene, Encoding Geranylgeranyl Reductase in Chlorobaculum tepidum

“…The genome of the archaeon Archaeoglobus fulgidus encodes four proteins with similarity to geranylgeranyl reductases (15). One of these proteins was recently shown to reduce the isoprenoid tail of menaquinone (15). However, the elution time of menaquinone in the CT1232 mutant was the same as that for the wild type (data not shown).…”

“…This distribution supports the conclusion that CT1232 is not involved in (B)Chl biosynthesis and that it must have a specialized function of limited occurrence in GSB. The genome of the archaeon Archaeoglobus fulgidus encodes four proteins with similarity to geranylgeranyl reductases (15). One of these proteins was recently shown to reduce the isoprenoid tail of menaquinone (15).…”

A novel geranylgeranyl reductase from the methanogenic archaeon Methanosarcina acetivorans displays unique regiospecificity

“…The ratio of A 280 /A 450 was approximately 10. As observed for some archaeal GGR-family enzymes [15,19], the bound flavin was reduced with dithionite but not with NAD(P)H (data not shown). First, the substrate specificity of MA1492 was assessed using various prenyl-chain-containing compounds.…”

“…The other archaeal PRs, which have been discovered based on their homology to GGR, play roles in various isoprenoid biosynthetic routes. One of the GGR homologues from hyperthermophile Archaeoglobus fulgidus is highly specific for menaquinone, and therefore it is supposedly involved in the generation of a C 35 fully saturated side chain of menaquinone-7(14H) [19]. An H. volcanii mutant deficient in the gene of a GGR homologue was shown to abolish the saturation at the x-terminal of dolichol phosphate as well as the full saturation of membrane lipids [20].…”

Geranylgeranyl Reductase and Ferredoxin from Methanosarcina acetivorans Are Required for the Synthesis of Fully Reduced Archaeal Membrane Lipid in Escherichia coli Cells

“…The reducing activity of S. acidocaldarius GGR suggests that the enzyme can be reduced by endogenous ferredoxin or some reducing agent in E. coli. This property is similar to that of A. fulgidus prenyl reductase, which can effectively reduce menaquinone in E. coli cells without help from other archaeal proteins (15). Our next focus will be to determine whether the ferredoxin from M. acetivorans is specific for GGR.…”