Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The scr genes located on plasmid pUR400 and responsible for sucrose (Scr) metabolism of Escherichia coli K12 and other enteric bacteria have been cloned on a 9.3 kb DNA fragment. The different genes were mapped by transposon insertion mutagenesis, by restriction endonuclease and deletion mapping, and the corresponding gene products were identified. Besides the known structural genes scrA, coding for an EnzymeII(Scr) (45 kD) of the phosphoenolypyruvate-dependent phosphotransferase system (PTS), and scrB, coding for a sucrose 6-phosphate hydrolase (invertase) (55 kD), two new structural genes were discovered. Gene scrK apparently codes for an intracellular and ATP-dependent fructokinase (39 kD), while scrY seems to code for a sucrose porin (58 kD) in the outer cell membrane. No genes for an Enzyme III(Scr) of the PTS or for (a) glycosyltransferase(s) were detected. The four genes form an scr operon (gene order, scrK scrY scrA scrB, transcription from K to B), regulated by a repressor (gene scrR, 37 kD) and inducible by sucrose, fructose and fructose-containing oligosaccharides.
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PMID:Plasmid-mediated sucrose metabolism in Escherichia coli K12: mapping of the scr genes of pUR400. 283 84

The Streptococcus mutans GS-5 gene, scrB, coding for sucrose 6-phosphate hydrolase activity has been cloned into Escherichia coli utilizing the bacteriophage replacement vector lambda L47.1. DNA sequences containing the gene were initially subcloned into the moderate-copy-number plasmid vector pLG339 to yield active subclones. However, due to the instability of the resultant chimeric plasmids, the gene was subsequently subcloned into the low-copy-number vector pOU61 to yield the stable hybrid plasmid pMH613. Both plasmids contain a 6.6-kilobase EcoRI fragment from strain GS-5 and express both hydrolase and sucrase activities. The relative position of the gene in the insert has been determined after Tn5 mutagenesis and deletion analysis. The cloned enzyme was purified to near homogeneity after gel filtration and anion-exchange chromatography, chromatofocusing, and preparative polyacrylamide gel electrophoresis. The purified enzyme displayed a molecular mass of 58 kilodaltons, which is significantly higher than the 48-kilodalton enzyme previously purified from S. mutans GS-5. These results suggest that processing of the hydrolase occurs in S. mutans.
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PMID:Isolation and characterization of the sucrose 6-phosphate hydrolase gene from Streptococcus mutans. 301 64

Storage of potato tubers at low temperatures leads to the accumulation of glucose and fructose in a process called 'cold sweetening'. The aim of this work was to investigate the role of sucrose-phosphatase (SPP) in potato tuber carbohydrate metabolism at low temperature (4 degrees C). To this end, RNA interference (RNAi) was used to reduce SPP expression in transgenic potato tubers. Analysis of SPP specific small interfering RNAs (siRNAs), SPP protein accumulation and enzyme activity indicated that SPP silencing in transgenic tubers was stable during the cold treatment. Analysis of soluble carbohydrates showed that in transgenic tubers, cold-induced hexogenesis was inhibited while, despite strongly reduced SPP activity, sucrose levels exceeded wild-type (WT) values four- to fivefold after 34 d of cold treatment. This led to a drastic change in the hexose-to-sucrose ratio from 1.9 in WT tubers to 0.15 to 0.11 in transgenic tubers, while the total amount of soluble sugars was largely unchanged in both genotypes. Sucrose-6(F)-phosphate (Suc6P), the substrate of SPP, accumulated in transgenic tubers in the cold which most likely enables the residual enzyme to operate with maximal catalytic activity in vivo and thus, in the long term, counterbalances reduced SPP activity in the transformants. Northern analysis revealed that cold-induced expression of vacuolar invertase (VI) was blocked in SPP-silenced tubers explaining a reduced sucrose-to-hexose conversion. Suc6P levels were found to negatively correlate with VI expression. A possible role of Suc6P in regulating VI expression is discussed.
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PMID:RNA interference-mediated repression of sucrose-phosphatase in transgenic potato tubers (Solanum tuberosum) strongly affects the hexose-to-sucrose ratio upon cold storage with only minor effects on total soluble carbohydrate accumulation. 1799 59