Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.1.18 (branching enzyme)
 628 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gene that encodes the mature branching enzyme II (BEII) protein from maize (Zea mays L.) endosperm was amplified by means of a polymerase chain reaction technique and inserted into a T7-based expression vector. Although this has been an efficient expression system of maize BEII in Escherichia coli, an example is presented in this report which allows a greater expression of mBEII protein from the bacterial system by changing only one codon. The key to the level of expression appears to be related to the conversion of the third thymine base in the 285 position codon of the mBEII cDNA to cytosine without altering the encoded mBEII protein product. The crude cell extracts of enzyme prepared from E.coli exhibited seven-fold higher expression of branching enzyme activity compared to expression of the native enzyme. The enzymes from wild-type and the silent mutation genes were purified. The proteins were indistinguishable kinetically and immunologically. Thus, we obtained a significantly improved expression of mBEII protein in the bacterial system.
 ...
PMID:High-level expression of branching enzyme II from maize endosperm in Escherichia coli. 975 44

Osmoregulated periplasmic glucans (OPGs) G protein (OpgG) is required for OPGs biosynthesis. OPGs from Escherichia coli are branched glucans, with a backbone of beta-1,2 glucose units and with branches attached by beta-1,6 linkages. In Proteobacteria, OPGs are involved in osmoprotection, biofilm formation, virulence and resistance to antibiotics. Despite their important biological implications, enzymes synthesizing OPGs are poorly characterized. Here, we report the 2.5 A crystal structure of OpgG from E.coli. The structure was solved using a selenemethionine derivative of OpgG and the multiple anomalous diffraction method (MAD). The protein is composed of two beta-sandwich domains connected by one turn of 3(10) helix. The N-terminal domain (residues 22-388) displays a 25-stranded beta-sandwich fold found in several carbohydrate-related proteins. It exhibits a large cleft comprising many aromatic and acidic residues. This putative binding site shares some similarities with enzymes such as galactose mutarotase and glucodextranase, suggesting a potential catalytic role for this domain in OPG synthesis. On the other hand, the C-terminal domain (residues 401-512) has a seven-stranded immunoglobulin-like beta-sandwich fold, found in many proteins where it is mainly implicated in interactions with other molecules. The structural data suggest that OpgG is an OPG branching enzyme in which the catalytic activity is located in the large N-terminal domain and controlled via the smaller C-terminal domain.
 ...
PMID:Structural analysis of Escherichia coli OpgG, a protein required for the biosynthesis of osmoregulated periplasmic glucans. 1531 17