Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The entire galactose (gal) operon of Klebsiella pneumoniae was isolated and functionally analyzed in Escherichia coli. The genes encoding galactokinase (galK), galactose-1-phosphate uridyltransferase (galT), and UDP-galactose-4-epimerase (galE) were mapped by complementation analysis. The gene order E-T-K was found to be identical to that of Salmonella spp. and E. coli. Analysis of the nucleotide sequence in the control region revealed significant homology with that of E. coli. Two major sites for transcriptional initiation, both mapped to a cytosyl residue, were identified by primer extension. When the operon is expressed in E. coli, the K. pneumoniae gal gene products make up about 30% of the total cellular proteins. The presence of a powerful promoter responsible for high level synthesis of the gal proteins was also demonstrated using beta-galactosidase as reporter.
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PMID:Cloning and expression of the Klebsiella pneumoniae galactose operon. 147 18

The genetic determinants for lactose utilization from Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 and galactose utilization from Lactococcus lactis subsp. cremoris MG 1363 were heterologously expressed in the lysine-overproducing strain Corynebacterium glutamicum ATCC 21253. The C. glutamicum strains expressing the lactose permease and beta-galactosidase genes of L. delbrueckii subsp. bulgaricus exhibited beta-galactosidase activity in excess of 1000 Miller units/ml of cells and were able to grow in medium in which lactose was the sole carbon source. Similarly, C. glutamicum strains containing the lactococcal aldose-1-epimerase, galactokinase, UDP-glucose-1-P-uridylyltransferase, and UDP-galactose-4-epimerase genes in association with the lactose permease and beta-galactosidase genes exhibited beta-galactosidase levels in excess of 730 Miller units/ml of cells and were able to grow in medium in which galactose was the sole carbon source. When grown in whey-based medium, the engineered C. glutamicum strain produced lysine at concentrations of up to 2 mg/ml, which represented a 10-fold increase over the results obtained with the lactose- and galactose-negative control, C. glutamicum 21253. Despite their increased catabolic flexibility, however, the modified corynebacteria exhibited slower growth rates and plasmid instability.
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PMID:Heterologous expression of lactose- and galactose-utilizing pathways from lactic acid bacteria in Corynebacterium glutamicum for production of lysine in whey. 1512 44