Glucose-6-phosphate isomerase from the hyperthermophilic archaeon Methanococcus jannaschii: characterization of the first archaeal member of the phosphoglucose isomerase superfamily.
ORF MJ1605, previously annotated as pgi and coding for the putative glucose-6-phosphate isomerase (phosphoglucose isomerase, PGI) of the hyperthermophilic archaeon Methanococcus jannaschii, was cloned and functionally expressed in Escherichia coli. The purified 80-kDa protein consisted of a single subunit of 45 kDa, indicating a homodimeric (alpha(2)) structure. The K(m) values for fructose 6-phosphate and glucose 6-phosphate were 0.04 mM and 1 mM, the corresponding V(max) values were 20 U/mg and 9 U/mg, respectively (at 50 degrees C). The enzyme had a temperature optimum at 89 degrees C and showed significant thermostability up to 95 degrees C. The enzyme was inhibited by 6-phosphogluconate and erythrose-4-phosphate. RT-PCR experiments demonstrated in vivo expression of ORF MJ1618 during lithoautotrophic growth of M. jannaschii on H(2)/CO(2). Phylogenetic analyses indicated that M. jannaschii PGI was obtained from bacteria, presumably from the hyperthermophile Thermotoga maritima.
Rudolph
Bente
B
Institut für Allgemeine Mikrobiologie, Christian-Albrechts-Universität Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
Hansen
Thomas
T
Schönheit
Peter
P
D003001:Cloning, Molecular; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D019848:Gene Expression Regulation, Archaeal; D005942:Gluconates / Q000378:metabolism; D005956:Glucose-6-Phosphate Isomerase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D017017:Methanococcus / Q000201:enzymology* / Q000235:genetics*; D008970:Molecular Weight; D010802:Phylogeny; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013403:Sugar Phosphates / Q000378:metabolism; D013696:Temperature; D014158:Transcription, Genetic
D004791:Enzyme Inhibitors; D005942:Gluconates; D021122:Protein Subunits; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013403:Sugar Phosphates; C026959:erythrose 4-phosphate; D005956:Glucose-6-Phosphate Isomerase; C008884:6-phosphogluconic acid