Application of Escherichia coli maltodextrin-phosphorylase for the continuous production of glucose-1-phosphate

1995 ◽  
Vol 17 (2) ◽  
pp. 140-146 ◽  
Author(s):  
Andreas Weinhäusel ◽  
Bernd Nidetzky ◽  
Christian Kysela ◽  
Klaus D. Kulbe
2005 ◽  
Vol 187 (24) ◽  
pp. 8322-8331 ◽  
Author(s):  
Renate Dippel ◽  
Winfried Boos

ABSTRACT The maltose/maltodextrin regulon of Escherichia coli consists of 10 genes which encode a binding protein-dependent ABC transporter and four enzymes acting on maltodextrins. All mal genes are controlled by MalT, a transcriptional activator that is exclusively activated by maltotriose. By the action of amylomaltase, we prepared uniformly labeled [14C]maltodextrins from maltose up to maltoheptaose with identical specific radioactivities with respect to their glucosyl residues, which made it possible to quantitatively follow the rate of transport for each maltodextrin. Isogenic malQ mutants lacking maltodextrin phosphorylase (MalP) or maltodextrin glucosidase (MalZ) or both were constructed. The resulting in vivo pattern of maltodextrin metabolism was determined by analyzing accumulated [14C]maltodextrins. MalP− MalZ+ strains degraded all dextrins to maltose, whereas MalP+ MalZ− strains degraded them to maltotriose. The labeled dextrins were used to measure the rate of transport in the absence of cytoplasmic metabolism. Irrespective of the length of the dextrin, the rates of transport at a submicromolar concentration were similar for the maltodextrins when the rate was calculated per glucosyl residue, suggesting a novel mode for substrate translocation. Strains lacking MalQ and maltose transacetylase were tested for their ability to accumulate maltose. At 1.8 nM external maltose, the ratio of internal to external maltose concentration under equilibrium conditions reached 106 to 1 but declined at higher external maltose concentrations. The maximal internal level of maltose at increasing external maltose concentrations was around 100 mM. A strain lacking malQ, malP, and malZ as well as glycogen synthesis and in which maltodextrins are not chemically altered could be induced by external maltose as well as by all other maltodextrins, demonstrating the role of transport per se for induction.


2019 ◽  
Vol 127 (4) ◽  
pp. 441-446 ◽  
Author(s):  
Yuji Aso ◽  
Mikikazu Tsubaki ◽  
Bui Hoang Dang Long ◽  
Ryo Murakami ◽  
Keisuke Nagata ◽  
...  

Author(s):  
Magali Roger ◽  
Thomas C. P. Reed ◽  
Frank Sargent

Escherichia coli is gram-negative bacterium that is a workhorse for biotechnology. The organism naturally performs a mixed-acid fermentation under anaerobic conditions where it synthesises formate hydrogenlyase (FHL-1). The physiological role of the enzyme is the disproportionation of formate in to H 2 and CO 2 . However, the enzyme has been observed to catalyse hydrogenation of CO 2 given the correct conditions, and so has possibilities in bio-based carbon capture and storage if it can be harnessed as a hydrogen-dependent CO 2 -reductase (HDCR). In this study, an E. coli host strain was engineered for the continuous production of formic acid from H 2 and CO 2 during bacterial growth in a pressurised batch bioreactor. Incorporation of tungsten, in place of molybdenum, in FHL-1 helped to impose a degree of catalytic bias on the enzyme. This work demonstrates that it is possible to couple cell growth to simultaneous, unidirectional formate production from carbon dioxide and develops a process for growth under pressurised gases. IMPORTANCE Greenhouse gas emissions, including waste carbon dioxide, are contributing to global climate change. A basket of solutions is needed to steadily reduce emissions, and one approach is bio-based carbon capture and storage. Here we present out latest work on harnessing a novel biological solution for carbon capture. The Escherichia coli formate hydrogenlyase (FHL-1) was engineered to be constitutively expressed. Anaerobic growth under pressurised H 2 and CO 2 gases was established and aqueous formic acid was produced as a result. Incorporation of tungsten in to the enzyme in place of molybdenum proved useful in poising FHL-1 as a hydrogen-dependent CO 2 reductase (HDCR).


1997 ◽  
Vol 58 (3) ◽  
pp. 157-166 ◽  
Author(s):  
Christian Eis ◽  
Richard Griessler ◽  
Maria Maier ◽  
Andreas Weinhäusel ◽  
Birgit Böck ◽  
...  

2008 ◽  
Vol 191 (3) ◽  
pp. 701-712 ◽  
Author(s):  
Christina Lengsfeld ◽  
Stefan Schönert ◽  
Renate Dippel ◽  
Winfried Boos

ABSTRACTMalT is the central transcriptional activator of allmalgenes inEscherichia coli. Its activity is controlled by the inducer maltotriose. It can be inhibited by the interaction with certain proteins, and its expression can be controlled. We report here a novel aspect ofmalgene regulation: the effect of cytoplasmic glucose and glucokinase (Glk) on the activity and the expression of MalT. Amylomaltase (MalQ) is essential for the metabolism of maltose. It forms maltodextrins and glucose from maltose or maltodextrins. We found that glucose above a concentration of 0.1 mM blocked the activity of the enzyme.malQmutants when grown in the absence of maltodextrins are endogenously induced by maltotriose that is derived from the degradation of glycogen. Therefore, the fact thatglk malQ+mutants showed elevatedmalgene expression finds its explanation in the reduced ability to remove glucose from MalQ-catalyzed maltodextrin formation and is caused by a metabolically induced MalQ−phenotype. However, even in mutants lacking glycogen, Glk controls endogenous induction. We found that overexpressed Glk due to its structural similarity with Mlc, the repressor ofmalT, binds to the glucose transporter (PtsG), releasing Mlc and thus increasingmalTrepression. In addition, even in mutants lacking Mlc (and glycogen), the overexpression ofglkleads to a reduction inmalgene expression. We interpret this repression by a direct interaction of Glk with MalT concomitant with MalT inhibition. This repression was dependent on the presence of either maltodextrin phosphorylase or amylomaltase and led to the inactivation of MalT.


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