Novel non-phosphorylative pathway of pentose metabolism from bacteria

Abstract

Pentoses, including D-xylose, L-arabinose, and D-arabinose, are generally phosphorylated to D-xylulose 5-phosphate in bacteria and fungi. However, in non-phosphorylative pathways analogous to the Entner-Dodoroff pathway in bacteria and archaea, such pentoses can be converted to pyruvate and glycolaldehyde (Route I) or α-ketoglutarate (Route II) via a 2-keto-3-deoxypentonate (KDP) intermediate. Putative gene clusters related to these metabolic pathways were identified on the genome of Herbaspirillum huttiense IAM 15032 using a bioinformatic analysis. The biochemical characterization of C785_RS13685, one of the components encoded to D-arabinonate dehydratase, differed from the known acid-sugar dehydratases. The biochemical characterization of the remaining components and a genetic expression analysis revealed that D- and L-KDP were converted not only to α-ketoglutarate, but also pyruvate and glycolate through the participation of dehydrogenase and hydrolase (Route III). Further analyses revealed that the Route II pathway of D-arabinose metabolism was not evolutionally related to the analogous pathway from archaea.

A combined experimental and modelling approach for the Weimberg pathway optimisation

“…Due to a lack of quantitative models, rational pathway design is not widely applied and time-consuming combinatorial approaches are used instead. For the Weimberg pathway of C. crescentus, only the XDH, the XAD and the KDXD had been partially kinetically characterized [38][39][40][41][42] , and although XLAs were characterized, e.g., from Azospirillum brasilense, Haloferax volcanii and partially from C. crescentus 9,10,33,49 , kinetic constants for C. crescentus were not available. As a prerequisite for rational pathway design and detailed kinetic modelling, we herein established purification procedures and kinetic enzyme assays, and in addition developed protocols for effective synthesis and determination of pathway intermediates.…”

“…1a) has gained major attention 8 . The pathway has been identified in several bacteria and archaea [9][10][11][12] , and is best understood for the oligotrophic freshwater bacterium Caulobacter crescentus, in which the involved enzymes are encoded in the D-xylose-inducible xylXABCD operon (CC0823-CC0819) 13 (Fig. 1b).…”

Effect of Lactic Acid Bacteria and Yeasts towards Chemical, Physical and Organoleptic Qualities of Mutton Salami

“…Hydroxyacetaldehyde (glycoaldehyde) causing brown color form. Other components of glycoaldehyde such as glioaksal and pyruvic aldehyde, allow for the brown coloring in fumigation [33]. The mutton salami color also influenced by pH and myoglobin, meat pigment concentration factor.…”

Structural insights into the catalytic and substrate recognition mechanisms of bacterial l‐arabinose 1‐dehydrogenase

“…Although the first and second metabolic pathways are phosphorylative pathways, the third pathway, found in bacteria and archaea, is partially equivalent to the nonphosphorylative Entner-Doudoroff pathway [5]. metabolism, in which L-KDP is converted to pyruvate and glycolaldehyde (Route I) [6,7], a-ketoglutarate (Route II) [8][9][10][11], or pyruvate and glycolate (Route III) [12]. L-Arabino-c-lactone is then converted to L-2-keto-3deoxypentonate (L-KDP) by L-arabinonolactonase (EC 3.1.1.15) and L-arabonate dehydratase (EC 4.2.1.25).…”

“…metabolism, in which L-KDP is converted to pyruvate and glycolaldehyde (Route I) [6,7], a-ketoglutarate (Route II) [8][9][10][11], or pyruvate and glycolate (Route III) [12].…”