Disease relevance of bla

• Wild-type SHV-1 and -5 beta-lactamases and their respective Asn276-->Asp mutants were expressed under isogenic conditions by cloning the respective bla genes into the pBCSK(+) plasmid and transforming Escherichia coli DH5alpha [1].
• Expression of Aeromonas caviae bla genes in Escherichia coli [2].
• Analysis of beta-lactamase content by isoelectric focusing, PCR assays specific for various bla genes, and DNA sequencing showed that the strain produced TEM-1, a Citrobacter freundii AmpC-related cephalosporinase, and CTX-M-3 [3].
• From now on, as the bla gene sequences of the most frequent Raoultella and Klebsiella species are available, the bla gene amplification method can be used to differentiate these species from each other, which the biochemical tests currently carried out in the clinical laboratory are unable to do [4].
• Salmonella typhimurium JMC isolated in Argentina harbors a bla gene located on a plasmid (pMVP-5) which confers transferable resistance to oxyiminocephalosporins, aztreonam, and ceftibuten [5].

High impact information on bla

• Cytosolic intermediates of murein biosynthesis and degradation thus act antagonistically to control beta-lactamase expression, thereby operating as a cell-wall sensing device [6].
• Addition of the muropeptide, anhMurNAc-tripeptide, which accumulates in beta-lactamase-overproducing mutants, counteracts the negative effect of UDP-MurNAc-pentapeptide, restoring the innate ability of AmpR to induce ampC expression in vitro [6].
• Shortening of bla transcripts by internal deletion or replacement of the 3' end with the corresponding segment of the ompA transcript had little effect on bla mRNA stability [7].
• The primary translation products predicted on the basis of the plasmid constructions were hybrid proteins starting with beta-lactamase or phage MS2 polymerase information followed by the total preinterferon [8].
• The analysis of hybrids between e(P4) and beta-lactamase demonstrated that a domain of e(P4) near its NH2' terminus was required for its function in hemin use [9].

Chemical compound and disease context of bla

• A mirror-repeat polypurine-polypyrimidine sequence inserted between the E. coli beta-lactamase gene (conferring ampicillin resistance) and its bla promoter strongly inhibited transcription of the beta-lactamase gene in vivo [10].
• The plasmid plP1066, harboured by by a methicillin-resistant Staphylococcus aureus strain isolated in France, carries genes specifying beta-lactamase [11].
• A novel natural TEM beta-lactamase with extended-spectrum activity, TEM-138, was identified in a ceftazidime-resistant clinical isolate of Salmonella enterica serovar Infantis [12].
• The chromosomally encoded beta-lactamase gene of Klebsiella oxytoca E23004, a strain resistant to cefoperazone and aztreonam, was cloned and expressed in Escherichia coli HB101 [13].
• Recombinant expression in Escherichia coli suggested that bla1 ( LVS ) did not encode a functional beta-lactamase, whereas bla2 ( LVS ) encoded a functional beta-lactamase that hydrolyzed penicillins but was inactive against third-generation cephalosporins, including cefprozil [14].

Biological context of bla

• The novel IRT's bla gene was sequenced, and the deduced amino acid sequence showed the amino acid replacement Arg for His-244 of the TEM-1 sequence [15].
• The latter was determined by use of a pair of reporter plasmids carrying supercoiling-dependent promoters pgyrA and ptopA, respectively, transcriptionally fused to the reporter gene bla coding for TEM-1 beta-lactamase [16].
• The inserted DNA fragments contain the beta-lactamase-encoding bla gene and upstream nucleotide sequences of various lengths [17].
• Sequence analysis of the bla genes revealed in each case an 858 bp open reading frame, differing from the TEM-1 sequence by five nucleotide substitutions [2].
• The bla gene from transposon Tn3 contains a homopyrimidine.homopurine sequence of 13 base pairs located just downstream of the RNA polymerase binding site [18].

Anatomical context of bla

• Premature termination of translation at codon position 26 reduced the stability of both the translated and ribosome-free segments of bla mRNA, whereas release of ribosomes just 30 codons further downstream resulted in normal stability for both segments [19].
• In cells grown at 24 degrees C the localization of beta-lactamase on the cell surface was almost quantitative (greater than 80% of the enzymatically active protein was exposed to the extracellular fluid) as determined by nitrocefin and penicillin G hydrolysis and trypsin accessibility [20].
• Orientation of the hybrid protein with the OmpA signal peptide showed that the nuclease was translocated into the periplasm and the beta-lactamase remained in the cytoplasm [21].
• Cells producing translocated forms of beta-lactamase can be directly selected as ampicillin-resistant colonies, and consequently a beta-lactamase fusion approach can be used for positive selection for export signals, and for rapid assessment of whether any protein expressed in Escherichia coli inserts into the bacterial cytoplasmic membrane [22].
• The calculated biophysical properties and computed discriminant scores (predictive of importability of signal peptides into mammalian microsomes) of the kinetoplastid signal sequences nevertheless are similar to those of ppalphaMF and Escherichia coli beta-lactamase both of which were imported [23].

Associations of bla with chemical compounds

• The expression of the inserted foreign gene (bla) encoding TEM beta-lactamase (Bla), can be induced by the addition of sucrose to the medium [24].
• These results indicate that the increase in beta-lactamase synthesis caused by lincomycin is due to an increase in the stability of bla mRNA rather than activation of its synthesis [25].
• We characterized the reversion of the mutant bla gene by a number of mutagens and in different genetic backgrounds and demonstrated that full ampicillin resistance can be restored only by a G-C-to-T-A transversion occurring at the first base of the codon [26].
• Oligonucleotide-directed mutagenesis of the beta-lactamase gene, bla, on pBR322 was used to change the codon for the active-site serine 70, AGC, to CGC, coding for arginine [26].
• It encoded a clavulanic acid-inhibited Ambler class A beta-lactamase, GIL-1, with a pI value of 7.5 and a molecular mass of ca. 29 kDa [27].

Other interactions of bla

• Examination of the other three bla(CTX-M) genes by cloning, sequencing, and PCR analysis revealed the presence of a complex sul1-type integron that includes open reading frame ORF513, which carries the bla gene and the surrounding DNA [28].
• The nucleotide sequences of Tn1 and Tn2 were determined over a 1,195-base-pair segment constituting most of the sequences of the tnpR and bla genes and the intervening region [29].
• Further, a DNA fragment (bla) coding mature beta-lactamase was joined to the region coding the C terminus of the pre-S2 repeat to stabilize the gene product [30].
• Deletion analyses revealed that the mini-F segment responsible for the inhibition of both processes was the promoter region of the sopA gene which had been cloned into a site upstream of the bla gene on pBR322 in such an orientation as to cause overexpression of bla [31].
• Plasmid pBR322, as well as its delta rom and delta bla derivatives, were lost from their host within 60 generations, but a number of delta tet derivatives were quite stable under the same conditions [32].

Analytical, diagnostic and therapeutic context of bla

• 9. The corresponding bla gene was identified by PCR and sequencing as a bla(TEM) gene [33].
• ESBLs were characterized by isoelectric focusing; multiplex PCR for bla genes of the SHV, TEM and CTX-M families; and DNA sequencing [34].
• The bla gene was transferable to Escherichia coli by electroporation of plasmid DNA [35].
• Furthermore, inspection of the complexes by electron microscopy confirms that at r greater than 2, the bla promoter can bind specifically a second RNAP particle, as compared to the 1:1 complex observed at r less than or equal to 2 [36].
• The expression of the bla gene carried on the plasmid was not affected by DNA titration or the addition of Ala [37].

References