Different glycolytic pathways for glucose and fructose in the halophilic archaeon Halococcus saccharolyticus

Abstract

We found out that all experiments described for Halococcus saccharolyticus in this paper were actually performed with Haloarcula marismortui. The incorrect assignment became obvious after purification and characterization of acetate/acetyl-CoA-converting enzymes from this organism. Using N-terminal amino acid sequences of the purified enzymes, we identified open reading frames (ORFs) in the partially sequenced genome of Haloarcula marismortui. We amplified these ORFs by PCR using template DNA from the organism used in our experiments and obtained sequences identical to those of the Haloarcular marismotui ORFs, thus identifying the organism as Haloarcula marismortui. In accordance, a partial 16S rRNA sequence of the strain was determined; the sequence corresponded to that of Haloarcula marismortui rather than to that of Halococcus saccharolyticus.

Sugar metabolism in the extremely halophilic bacteriumSalinibacter ruber

“…Glucose is metabolized via the modi¢ed Entner^Doudoro¡ pathway, while fructose utilization almost entirely follows the EmbdenM eyerhof pathway. Glucose-grown cells showed increased activities of gluconate dehydratase and 2-keto-3-deoxygluconate kinase, while fructose-grown cells contained higher activities of ketohexokinase and fructose-1-phosphate kinase, the key enzymes of the modi¢ed EmbdenM eyerhof pathway [9]. Our studies with S. ruber suggest that this organism uses the enzymes of the classic Entner^Doudoro¡ pathway, with G-6-P dehydrogenase as a key enzyme, rather than the archaeal-type modi¢cation based on glucose dehydrogenase, or the Embden^Meyerhof pathway with FDP aldolase as the key enzyme.…”

“…KDPG aldolase (EC 4.1.2.14) was determined by measuring the formation of KDPG from glyceraldehyde-3phosphate and pyruvate [9]. The assay mixture (1 ml) contained 100 Wmol Tris^HCl, pH 8.5, KCl as indicated, 100 Wmol pyruvate, 1 or 2 Wmol glyceraldehyde-3-phosphate (Sigma), and cell extract (between 1 and 1.5 mg protein).…”

“…In the halophilic Archaea glucose is metabolized using a modi¢cation of the Entner^Doudoro¡ pathway, in which the phosphorylation step is postponed. Glucose is oxidized via gluconate to 2-keto-3-deoxygluco-nate, followed by phosphorylation to 2-keto-3-deoxy-6phosphogluconate (KDPG), which is then split into pyruvate and glyceraldehyde-3-phosphate [8,9]. However, those halophilic Archaea that degrade fructose do so by means of the glycolytic Embden^Meyerhof pathway, with fructose-1,6-bisphosphate (FBP) aldolase as the key enzyme [9^13].…”

Regulation of acetate and acetyl-CoA converting enzymes during growth on acetate and/or glucose in the halophilic archaeonHaloarcula marismortui

“…Various halophilic archaea, including Haloarcula marismortui, grow on glucose, which is degraded via a modified, semiphosphorylated Entner-Doudoroff (ED) pathway [1]. It has been shown that during exponential growth on glucose significant amounts of acetate were formed [2].…”

In vivo31P and13C NMR investigations ofRhodococcus rhodochrousmetabolism and behaviour during biotransformation processes

“…First, in vivo 13 C NMR, especially combined with the use of 13 C-labelled substrates, is very useful to describe carbon metabolic routes. However, it can be noted that the central carbon metabolism of bacteria issued from the environment has been rarely studied except, for instance, in the case of micro-organisms from wastewater treatment plants (Lemos et al 2003(Lemos et al , 2007 or halophilic bacteria (Johnsen et al 2001). Second, in vivo 31 P NMR allows to quantify the signals of different energetic markers such as NMP, NDP, NTP (nucleotides mono-, di-, and tri-phosphates, respectively) and polyphosphates.…”