Regulation der Glucose‐6‐phosphat‐Dehydrogenase aus dem obligat methylotrophen Bakterium Pseudomonas W 6

Abstract

Mikroorganismen, die auf Methan, Methanol, Mono-, Di-, Trimethylamin als einzige Kohlenstoffund Energiequelle wachsen, werden als methylotroph bezeichnet. Die Assimilation dieser reduzierten C,-Verbindungen erfolgt uber zwei prinzipiell verschiedene Sequenzen. WLhrend im Serin-Weg ( 8 . QUAYLE 1972) der erste Assimilationsschritt im Transfer der Hydroxymethylgruppe der aktivierten C,-Verbindung auf Glycin unter Bildung von Serin besteht, erfolgt die Assimilation im Ribulosemonophosphat-Zyklus oder Hexulosephosphat-Weg ( 8 . QUAYLE 1972) diirch Addition bzw. Kondensation von Formaldehyd an Ribulose-5-phosphat unter Bildung von ~-arabino-3-Hexulose-6-phosphat (KEMP 1974).

Distribution of Methanol Carbon Between Assimilation and Oxidation Pathways in Methanol-grown Pseudomonas C

“…(iv) Evidence for net incorporation of CO, in methanol-grown Pseudomonas C is supported by the following: (a) Battat et al (1 974) showed that CO, is necessary for obtaining high yields of this bacterium; (b) in methanol-grown Pseudomonas W6, a bacterium similar in many respects to Pseudomonas C (Miethe & Babel, 1976), Babel & Loffhagen (1977) reported the presence of high activities of phosphoenolpyruvate carboxylase and pyruvate carboxylase, and they suggested that a high rate of carboxylation is necessary for synthesis of C , dicarboxylic acids in methylotrophic bacteria which use the RMP pathway for the assimilation of Cl compounds and which possess an incomplete tricarboxylic acid cycle that serves only for biosynthetic purposes; ( c ) the possibility that the incorporation of 14C0, is primarily due to exchange reactions (Quayle, 1961) seems unlikely since these methylotrophic bacteria when grown on methanol must synthesize C4 dicarboxylic acids by carboxylation of C, acids.…”

Characterization of the Assimilatory and Dissimilatory Pathways of Carbon Metabolism during Growth of Methylophilus methylotrophus on Methanol

“…Glc-6-P dehydrogenases exhibiting dual coenzyme specificity have been found in various methylotrophic bacteria, e.g. Pseudomonas W6 (Miethe & Babel, 1976), Methylomonas M15 (Steinbach et al, 1978), Pseudomonas C (Ben-Bassat & Goldberg, 1980) and Pseudomonas okovorans (Sokolov et al, 1980). The molecular weights and subunit structures are closely similar for the enzymes from Methylophilus methylotrophus, Methylomonas M 15 and Pseudomonas oleovorans.…”

Regulation and properties of glucose-6-phosphate dehydrogenase: A review

“…For NAD + linked reaction, the inhibition was linear non competitive when NAD + was used as varied substrate and glucose-6-phosphate was non saturating and when glucose-6-phosphate was used as varied substrate the inhibition by NADH was noncompetitive without any correlation with NAD + being saturating or non saturating (Olive et al, 1971). The enzyme isolated from obligate methylotrophic bacterium Pseudomonas W6 is not inhibited by NADPH but by NADH (Miethe and Babel, 1976), however the purified enzyme from Methylomonas M15 was reported to be inhibited by both NADPH and NADH (Steinbach et al, 1978). Grossman and McGowan (1975) reported that NADPH inhibits the activity of cyanobacterial G6PD, which was later on confirmed by Pelroy et al (1976).…”