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Biological Process for Butanol Production
Published in Jay J. Cheng, Biomass to Renewable Energy Processes, 2017
Maurycy Daroch, Jian-Hang Zhu, Fangxiao Yang
Glycolysis, a breakdown of simple carbohydrate that generates ATP under anaerobic conditions, is a typical entry point to the fermentation when feedstocks such as starch, molasses, or lignocellulose are used for fermentation. Glucose transported into the cell is mediated by a phosphoenol pyruvate-dependent phosphotransferase system. In more complex substrates, pentoses are metabolized via the pentose phosphate pathway through transketolase–transaldolase sequence and reconnect with metabolism as fructose 6-phosphate and glyceraldehyde 3-phosphate (Jones and Woods, 1986). Glycolysis in C. acetobutylicum is performed through Embden–Meyerhoff–Parnas (EMP) pathway previously described in Chapter 7. In short, glucose (six carbon sugar) molecules imported to the cytosol are enzymatically phosphorylated at positions 1 and 6 and subsequently lysed by an aldolase to yield two phosphorylated molecules of glyceraldehyde-3-phosphate. Phosphorylation steps require 2 molecules of ATP per molecule of glucose. Glyceraldehyde-3-phosphate then undergoes a rearrangement and non-enzymatic phosphorylation at the expense of NAD+ that generates a molecule of 1,3-diphosphoglycerate. Finally, each of the two 1,3-diphosphoglycerates undergoes two subsequent enzymatic dephosphorylations that produce two molecules of ATP each (4 in total), yielding a net gain from glycolysis of 2 ATP molecules per molecule of glucose. Final product of glycolysis – pyruvate is a starting material for the next step of biosynthesis.
Introduction
Published in James E. Ferrell, Systems Biology of Cell Signaling, 2021
Furthermore, whereas the bacterial system is shallow, the EGFR system is deep. In the three bacterial examples shown in Figure 1.2, the histidine kinase directly phosphorylates the terminal effector of the pathway, the response regulator protein. In some bacterial pathways (e.g. the RcsCBD system, not shown in Figure 1.2), there is a third protein (a phosphotransferase protein) interposed between the kinase and the terminal effector. But still-longer pathways have not been found, and in general bacterial signaling makes use of a small number of intermediaries.
Lysosomal Storage Disorders and Enzyme Replacement Therapy
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2020
A deficiency of the exoglycosidase β-glucuronidase (GUS), which is required for the degradation of the GAGs dermatan sulfate, heparan sulfate, and chondroitin sulfate causes MPS VII (Sly syndrome). GUS, a member of family 2 β-glycosidases, is active as a tetramer of four identical subunits of 75 kDa consisting of 629 amino acid residues including a 22 residue long signal sequence (Oshima et al., 1987). Glycosylation sites of GUS are at Asn173, Asn272, Asn420 and Asn631 with the oligosaccharide Man7GlcNAc2-M6P being attached to Asn272 and Asn420 and Man6GlcNAc2-M6P to Asn631, as obtained from site-specific glycoproteomic analysis (Hassan et al., 2013; Bones et al., 2011; see also Shipley et al., 1993); hence these Man-rich oligosaccharides are the primary carriers of the M6P tag and the phosphorylation of terminal Man residues in oligosaccharide side chains of lysosomal enzymes is a prerequisite for their targeting to the lysosome through recognition in the trans-Golgi network by specific transmembrane mannose 6-phosphate (M6P) receptors. The M6P group is added exclusively to the N-linked oligosaccharides of lysosomal soluble hydrolases when passing the cis-Golgi network. Phosphorylation is achieved by the catalytic action of UDPGlcNAc:glycoprotein N-acetylglucosamine-1-phosphotransferase and its substrate uridine diphosphate N-acetylglucosamine (UDPGlcNAc) from which it transfers N-acetylglucosamine-1-phosphate (GlcNAc-1-P) to the 6-position of the respective mannose residues linked to high mannose-type oligosaccharide side chains. The final mannose phosphoester results from cleavage of the capping GlcNAc moieties in presence of the enzyme N-acetylglucosaminyl phosphodiesterase (Reitman and Kornfeld, 1981; Coutinho et al., 2012, 2012a). The structural motif that enables recognition of lysosomalhumanGUSbyN-acetylglucosamine-1-phosphotransferase includes Lys197 and residues 179-201 of GUS (Hassan et al., 2013).
Principles for quorum sensing-based exogeneous denitrifier enhancement of nitrogen removal in biofilm: a review
Published in Critical Reviews in Environmental Science and Technology, 2023
Ying-nan Zhu, Jinfeng Wang, Qiuju Liu, Ying Jin, Lili Ding, Hongqiang Ren
The phosphotransferase system (PTS) is a group of enzymes with specific functions and composed of enzyme I (EI), histidine phosphate carrier protein (HPr or NPr), and enzyme II (EII) compounds. It mainly includes two categories: carbohydrate PTS (PTSSugar) and nitrogen PTS (PTSNtr). Carbohydrate PTS is responsible for phosphorylating carbohydrates and then transporting them into cells, thereby regulating protein activity, carbon metabolism, and QS (Ha et al., 2018). In the case of nitrogen deficiency, the concentration of 2-OG increases (as a signal for nitrogen starvation), which directly inhibits the EI subunit of PTSSugar and prevents glucose input (Doucette et al., 2011). When the HPr subunit of PTSSugar binds to LsrK, it inactivates the kinase LsrK, which then inhibits AI-2 phosphorylation and its QS function. This indicates the ability of bacteria to respond rapidly to changing nutrient levels in terms of growth density (Ha et al., 2018).
Phenotypic traits of carbon source utilization in environmental Salmonella strains isolated from river water
Published in International Journal of Environmental Health Research, 2022
Cristóbal Chaidez, Felipe De Jesús Peraza-Garay, José Andrés Medrano-Félix, Nohelia Castro-Del Campo, Osvaldo López-Cuevas
On the other hand, the environmental origin of Salmonella strains may represent a positive factor for their utilization of environmental carbon sources, leading to similar patterns for the metabolism of diverse carbon sources, including N-acetyl D-glucosamine, D-glucosaminic acid, glucose-1-phosphate, D-galactonic acid-gamma lactone and pyruvic acid. In fact, previous studies established that Salmonella is able to use D-glucosaminic acid by internalization using phosphotransferase transport systems (PTS) for the production of glyceraldehyde-3-phosphate and pyruvate, which can be easily metabolized in Salmonella (Miller et al. 2013). Medrano-Félix et al. (2017) evaluated the metabolic activity of environmental strains of Salmonella Oranienburg and Saintpaul and showed their utilization of environmental carbon sources under laboratory growth conditions, exposure in river water and in epithelial cells compared to clinical strains.
Genetic and substrate-level modulation of Bacillus subtilis physiology for enhanced extracellular human interferon gamma production
Published in Preparative Biochemistry and Biotechnology, 2018
Nitin Kumar, Rajat Pandey, Ashish Anand Prabhu, Veeranki Venkata Dasu
Substrate-level modulation of the B. subtilis physiology was performed by replacing the glucose from the defined synthetic medium with the addition of equal carbon mole of various carbon sources. Following phosphotransferase transport system (PTS) and non-PTS sugars, sugar alcohols and organic acids were used as a carbon source, PTS sugars: glucose and sorbitol, non-PTS sugar and sugar alcohols: lactose, glycerol and gluconate, organic acids: pyruvate, acetate, and malate. Organic acids were used and compared at 2 g L−1 initial concentration, as the higher initial concentration of organic acids is strongly inhibitory to B. subtilis growth.