Control of glycolytic flux in Zymomonas mobilis by glucose 6-phosphate dehydrogenase activity

Journal Article · Sat Jul 20 04:00:00 EDT 1996 · Biotechnology and Bioengineering

DOI:https://doi.org/10.1002/(SICI)1097-0290(19960720)51:2<190::AID-BIT8>3.3.CO;2-L· OSTI ID:268000

Snoep, J L ^[1]; Arfman, N; Yomano, L P; Ingram, L O ^[1]; Westerhoff, H V ^[2]; Conway, T ^[3]

---

1. Univ. of Florida, Gainesville, FL (United States). Dept. of Microbiology and Cell Science
2. Free Univ., Amsterdam (Netherlands). Dept. of Microbial Physiology
3. Ohio State Univ., Columbus, OH (United States). Dept. of Microbiology

Alycolytic genes in Zymomonas mobilis are highly expressed and constitute half of the cytoplasmic protein. The first four genes (glf, zwf, edd, glk) in this pathway form an operon encoding a glucose permease, glucose 6-phosphate dehydrogenase (G6-P dehydrogenase), 6-phosphogluconate dehydratase, and glucokinase, respectively. Each gene was overexpressed from a tac promoter to investigate the control of glycolysis during the early stages of batch fermentation when flux (qCO{sub 2}) is highest. Almost half of flux control appears to reside with G6-P dehydrogenase (C{sub G6-P dehydrogenase}{sup J} = 0.4). Although Z. mobilis exhibits one of the highest rates of glycolysis known, recombinants with elevated G6-P dehydrogenase had a 10% to 13% higher glycolytic flux than the native organism. A small increase in flux was also observed for recombinants expressing glf. Results obtained did not allow a critical evaluation of glucokinase and this enzyme may also represent an important control point. 6-Phosphogluconate dehydratase appears to be saturating at native levels. With constructs containing the full operon, growth rate and flux were both reduced, complicating interpretations. However, results obtained were also consistent with G6-P dehydrogenase as a primary site of control. Flux was 17% higher in operon constructs which exhibited a 17% increase in G6-P dehydrogenase specific activity, relative to the average of other operon constructs which contain a frameshift mutation in zwf.

• DOE Contract Number: FG02-90ER20002
• OSTI ID: 268000
• Journal Information: Biotechnology and Bioengineering, Journal Name: Biotechnology and Bioengineering Journal Issue: 2 Vol. 51; ISSN 0006-3592; ISSN BIBIAU
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
BIOSYNTHESIS
ENZYME ACTIVITY
ETHANOL
FERMENTATION
GENE REGULATION
GLUCOSE
GROWTH
OXIDOREDUCTASES
ZYMOMONAS MOBILIS