scholarly journals Biosynthesis of the Escherichia coli K5 polysaccharide, a representative of group II capsular polysaccharides: polymerization in vitro and characterization of the product.

1991 ◽  
Vol 173 (13) ◽  
pp. 4088-4094 ◽  
Author(s):  
A Finke ◽  
D Bronner ◽  
A V Nikolaev ◽  
B Jann ◽  
K Jann
Keyword(s):  
Escherichia Coli ◽  
Capsular Polysaccharides ◽  
Group Ii ◽  
K5 Polysaccharide

scholarly journals Characterization of a Dye-Decolorizing Peroxidase from Irpex lacteus Expressed in Escherichia coli: An Enzyme with Wide Substrate Specificity Able to Transform Lignosulfonates

2021 ◽  
Vol 7 (5) ◽  
pp. 325
Author(s):  
Laura Isabel de de Eugenio ◽  
Rosa Peces-Pérez ◽  
Dolores Linde ◽  
Alicia Prieto ◽  
Jorge Barriuso ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Inclusion Bodies ◽  
Veratryl Alcohol ◽  
Dye Decolorization ◽  
Irpex Lacteus ◽  
Type D ◽  
Lignin Peroxidases

A dye-decolorizing peroxidase (DyP) from Irpex lacteus was cloned and heterologously expressed as inclusion bodies in Escherichia coli. The protein was purified in one chromatographic step after its in vitro activation. It was active on ABTS, 2,6-dimethoxyphenol (DMP), and anthraquinoid and azo dyes as reported for other fungal DyPs, but it was also able to oxidize Mn2+ (as manganese peroxidases and versatile peroxidases) and veratryl alcohol (VA) (as lignin peroxidases and versatile peroxidases). This corroborated that I. lacteus DyPs are the only enzymes able to oxidize high redox potential dyes, VA and Mn+2. Phylogenetic analysis grouped this enzyme with other type D-DyPs from basidiomycetes. In addition to its interest for dye decolorization, the results of the transformation of softwood and hardwood lignosulfonates suggest a putative biological role of this enzyme in the degradation of phenolic lignin.

In vitro functional characterization of overproduced Escherichia coli katF/rpoS gene product

Biochemistry ◽  
1993 ◽  
Vol 32 (41) ◽  
pp. 11112-11117 ◽  
Author(s):  
Lam H. Nguyen ◽  
Debra B. Jensen ◽  
Nancy E. Thompson ◽  
Daniel R. Gentry ◽  
Richard R. Burgess
Keyword(s):  
Escherichia Coli ◽  
Gene Product ◽  
Functional Characterization ◽  
Rpos Gene

scholarly journals Overexpression of UDP-glucose dehydrogenase in Escherichia coli results in decreased biosynthesis of K5 polysaccharide

2003 ◽  
Vol 374 (3) ◽  
pp. 767-772 ◽  
Author(s):  
Elisabet ROMAN ◽  
Ian ROBERTS ◽  
Kerstin LIDHOLT ◽  
Marion KUSCHE-GULLBERG
Keyword(s):  
Escherichia Coli ◽  
Capsular Polysaccharide ◽  
Glucose Dehydrogenase ◽  
Fold Increase ◽  
Extra Copy ◽  
Polysaccharide Biosynthesis ◽  
Polysaccharide Production ◽  
Significant Difference ◽  
K5 Polysaccharide

The Escherichia coli K5 capsular polysaccharide (glycosaminoglycan) chains are composed of the repeated disaccharide structure: -GlcAβ1,4-GlcNAcα1,4-(where GlcA is glucuronic acid and GlcNAc is N-acetyl-d-glucosamine). The GlcA, present in most glycosaminoglycans, is donated from UDP-GlcA, which, in turn, is generated from UDP-glucose by the enzyme UDP-glucose dehydrogenase (UDPGDH). The formation of UDP-GlcA is critical for the biosynthesis of glycosaminoglycans. To investigate the role of UDPGDH in glycosaminoglycan biosynthesis, we used K5 polysaccharide biosynthesis as a model. E. coli was transformed with the complete gene cluster for K5 polysaccharide production. Additional transformation with an extra copy of UDPGDH resulted in an approx. 15-fold increase in the in vitro UDPGDH enzyme activity compared with the strain lacking extra UDPGDH. UDP-GlcA levels were increased 3-fold in overexpressing strains. However, metabolic labelling with [14C]glucose showed, unexpectedly, that overexpression of UDPGDH lead to decreased formation of K5 polysaccharide. No significant difference in the K5 polysaccharide chain length was observed between control and overexpressing strains, indicating that the decrease in K5-polysaccharide production most probably was due to synthesis of fewer chains. Our results suggest that K5-polysaccharide biosynthesis is strictly regulated such that increasing the amount of available UDP-GlcA results in diminished K5-polysaccharide production.

scholarly journals Molecular characterization of human stathmin expressed in Escherichia coli: site-directed mutagenesis of two phosphorylatable serines (Ser-25 and Ser-63)

1994 ◽  
Vol 300 (2) ◽  
pp. 331-338 ◽  
Author(s):  
P A Curmi ◽  
A Maucuer ◽  
S Asselin ◽  
M Lecourtois ◽  
A Chaffotte ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Kinase ◽  
Glutamic Acid ◽  
Protein Characterization ◽  
Mitogen Activated Protein Kinase ◽  
Helical Conformation ◽  
In Vitro Mutagenesis ◽  
Native Protein

Stathmin, a probable relay protein possibly integrating multiple intracellular regulatory signals [reviewed in Sobel (1991) Trends Biochem. Sci. 16, 301-305], was expressed in Escherichia coli at levels as high as 20% of total bacterial protein. Characterization of the purified recombinant protein revealed that it had biochemical properties very similar to those of the native protein. It is a good substrate for both cyclic AMP-dependent protein kinase (PKA) and p34cdc2, on the same four sites as the native eukaryotic protein. As shown by m.s., the difference in isoelectric points from the native protein is probably due to the absence of acetylation of the protein produced in bacteria. C.d. studies indicate that stathmin probably contains about 45% of its sequence in an alpha-helical conformation, as also predicted for the sequence between residues 47 and 124 by computer analysis. Replacement of Ser-63 by alanine by in vitro mutagenesis resulted in a ten times less efficient phosphorylation of stathmin by PKA which occurred solely on Ser-16, confirming that Ser-63 is the major target of this kinase. Replacement of Ser-25, the major site phosphorylated by mitogen-activated protein kinase in vitro and in vivo, by the charged amino acid glutamic acid reproduced, in conjunction with the phosphorylation of Ser-16 by PKA, the mobility shift on SDS/polyacrylamide gels induced by the phosphorylation of Ser-25. This result strongly suggests that glutamic acid in position 25 is able to mimic the putative interactions of phosphoserine-25 with phosphoserine-16, as well as the resulting conformational changes that are probably also related to the functional regulation of stathmin.

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