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)

Investigations of possible regulators of Bacteroides fragilis glutamine synthetase (GS) activity were done in Escherichia coli using a compatible dual-plasmid system. The B. fragilis glnA gene, together with upstream and downstream flanking regions, was cloned onto the low copy number plasmid pACYC184 and expressed in the E. coli glnA ntrB ntrC deletion strain, YMC11. GS activity was monitored following co-transformation with a B. fragilis genomic library carried on the compatible plasmid pEcoR251. A gene was cloned that caused a twofold increase in B. fragilis GS activity but did not affect the activity of the E. coli GS enzyme or the B. fragilis sucrase (ScrL). Deletion of the B. fragilis glnA downstream region decreased basal levels of GS activity, but did not affect the ability of the cloned gene to increase the B. fragilis GS activity. Reporter gene analysis, using the B. fragilis glnA promoter region fused to the promoterless Clostridium acetobutylicum endoglucanase gene, showed no increase in reporter gene activity. This demonstrated that the increase in GS activity was not regulated at the transcriptional level, and that the cloned gene product was not affecting the copy number of the plasmid in trans. Sequence data indicated that the cloned gene had good amino acid identity to a range of elongation factor P (EF-P) proteins, the highest being to that of a Synechocystis sp (48%), and the least to Mycobacterium genitalium (27%). Amino acid identity to the E. coli EF-P was intermediate (37%). A possible role for EF-P in enhancing translation of the B. fragilis glnA mRNA is proposed.
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PMID:Cloning of an EF-P homologue from Bacteroides fragilis that increases B. fragilis glutamine synthetase activity in Escherichia coli. 964 40

The haloalkane-degrading bacteria Rhodococcus rhodochrous NCIMB13064, Pseudomonas pavonaceae 170, and Mycobacterium sp. strain GP1 share a highly conserved haloalkane dehalogenase gene (dhaA). Here, we describe the extent of the conserved dhaA segments in these three phylogenetically distinct bacteria and an analysis of their flanking sequences. The dhaA gene of the 1-chlorobutane-degrading strain NCIMB13064 was found to reside within a 1-chlorobutane catabolic gene cluster, which also encodes a putative invertase (invA), a regulatory protein (dhaR), an alcohol dehydrogenase (adhA), and an aldehyde dehydrogenase (aldA). The latter two enzymes may catalyze the oxidative conversion of n-butanol, the hydrolytic product of 1-chlorobutane, to n-butyric acid, a growth substrate for many bacteria. The activity of the dhaR gene product was analyzed in Pseudomonas sp. strain GJ1, in which it appeared to function as a repressor of dhaA expression. The 1,2-dibromoethane-degrading strain GP1 contained a conserved DNA segment of 2.7 kb, which included dhaR, dhaA, and part of invA. A 12-nucleotide deletion in dhaR led to constitutive expression of dhaA in strain GP1, in contrast to the inducible expression of dhaA in strain NCIMB13064. The 1, 3-dichloropropene-degrading strain 170 possessed a conserved DNA segment of 1.3 kb harboring little more than the coding region of the dhaA gene. In strains 170 and GP1, a putative integrase gene was found next to the conserved dhaA segment, which suggests that integration events were responsible for the acquisition of these DNA segments. The data indicate that horizontal gene transfer and integrase-dependent gene acquisition were the key mechanisms for the evolution of catabolic pathways for the man-made chemicals 1, 3-dichloropropene and 1,2-dibromoethane.
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PMID:Roles of horizontal gene transfer and gene integration in evolution of 1,3-dichloropropene- and 1,2-dibromoethane-degradative pathways. 1073 62

Counterselectable markers are powerful tools in genetics because they allow selection for loss of a genetic marker rather than its presence. In mycobacteria, a widely used counterselectable marker is the gene encoding levan sucrase (sacB), which confers sensitivity to sucrose, but frequent spontaneous inactivation complicates its use. Here we show that the Escherichia coli galactokinase gene (galK) can be used as a counterselectable marker in both Mycobacterium smegmatis and Mycobacterium tuberculosis. Expression of E. coli galK, but not the putative M. tuberculosis galK, conferred sensitivity to 2-deoxy-galactose (2-DOG) in both M. smegmatis and M. tuberculosis. We tested the utility of E. coli galK as a counterselectable marker in mycobacterial recombination, both alone and in combination with sacB. We found that 0.5% 2-DOG effectively selected recombinants that had lost the galK marker with the ratio of galK loss/galK mutational inactivation of approximately 1:4. When we combined galK and sacB as dual counterselectable markers and selected for dual marker loss on 0.2% 2-DOG/5% sucrose, 98.6-100% of sucrose/2-DOG resistant clones had undergone recombination, indicating that the frequency of mutational inactivation of both markers was lower than the recombination frequency. These results establish a new counterselectable marker system for use in mycobacteria that can shorten the time to generate unmarked mutations in M. smegmatis and M. tuberculosis.
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PMID:An improved counterselectable marker system for mycobacterial recombination using galK and 2-deoxy-galactose. 2085 Nov 71