[Genetic determinants of antibacterial resistance among nosocomial Escherichia coli, Klebsiella spp., and Enterobacter spp. isolates collected in Russia within 2003-2007].

Nosocomial bacterial isolates collected within 2003-2004 (n=411) and 2005-2007 (n=422) were highly resistant to cephalosporins III-IV and antibacterials of other groups (aminoglycosides, fluoroquinolons, chloramphenicol, and co-trimoxazole). Genes encoding TEM, SHV, CTX-M, OXA-2, and AmpC types of beta-lactamases (BLs) in the E. coli, Klebsiella spp., and Enterobacter spp. isolates were detected using polymerase chain reaction (PCR). Prevalent CTX-M-type BLs were detected in 85% of the E. coli, 87% of the Klebsiella spp., and 38% of the Enterobacter spp. isolates of the first strain collection and in 94% of the E. coli, 91% of the Klebsiella spp., and 38% of the Enterobacter spp. isolates of the second one. Genes belonging to three subtypes of blacTx-M genes were identified: bla(CTX-M-1) (228 bla(CTX-M-15) and six bla(CTX-M-3) of the first strain collection; 275 bla(CTX-M-15), three bla(CTX-M-3), and one bla(CTX-M-22) of the second one), bla(CTX-M-2) (one bla(CTX-M-5) of the first strain collection and one bla(CTX-M-2) of the second one), bla(CTX-M-9) (17 bla(CTX-M-14) and one bla(CTX-M-9) of the first strain collection; seven bla(CTX-M-14) and one bla(CTX-M-9) of the second one). Three isolates of the first strain collection and one isolate of the second one carried two genes belonging to two different subtypes, i.e., bla(CTX-M-15) and bla(CTX-M-14) simultaneously. The bacterial isolates had high levels of associative resistance to ciprofloxacin, co-trimoxazole, gentamicin, amikacin, and chloramphenicol associated with the resistance gene cassettes aadA1, aadA2, aadA5, aadB, aacA4, aac(6')Ib; dfrA1, dfrA5, dfrA12, dfrA17, cmlA1, ereA2, and catB8 in the class 1 integrons and the resistance gene cassettes dfrA1, sat1, and aadA1 in the class 2 integrons.

[Genetic environments of bla(CTX-M) genes located on conjugative plasmids of Enterobacteriaceae nosocomial isolates collected in Russia within 2003-2007].

The study showed that bla(CTX-M) genes were present in the genomes of 71% of cephalosporin resistant Enterobacteriaceae nosocomial isolates (n=833) collected in Russian hospitals within 2003-2007, including 91% of E.coli, 90% of Klebsiella spp., 38% of Enterobacter spp., 31% of Citrobacter spp. (n=9), and 36% of the other Enterobacteriaceae species. The genes belonging to the following subtypes (clusters) were identified: bla(CTX-M-1) (529 bla(CTX-M-15) genes; 25 bla(CTX-M-3) genes; 1 bla(CTX-M-22) gene, 1 bla(CTX-M-23) gene, and 1 bla(CTX-M-34) gene); bla(CTX-M-2) (1 bla(CTX-M-2) gene, and 4 bla(CTX-M-5) genes), and bla(CTX-M-9) (2 bla(CTX-M-9) genes, and 28 bla(CTX-M-14) genes). It was shown that bla(CTX-M) genes were located on high-molecular weight (60-160 bp) conjugative plasmids belonging mainly to the incompatibility groups IncF, IncL/M and IncA/C (bla(CTX-M-15) gene); IncL/M(bla(CTX-M-3) gene); and IncF, IncL/Mand IncI1-ly (CTX-M-14 gene). The gene environments of bla(CTX-M) genes were shown specific for the subtype of the genes. A mobile genetic element ISEcp1 (in some cases deleted or inserted by IS26, IS1, IS10, resTn2, or resTn3 sequences, in direct or reverse position) were detected upstream of bla(CTX-M-3), bla(CTX-M-14), and bla(CTX-M-15) genes. A special characteristic was the sequence between ISEcp1 and bla(CTX-M) gene: 48 bp for bla(CTX-M-15) (except 1 E.coli isolate having such a sequence deleted by 3 bp); 127 bp for bla(CTX-M-3); 42 bp for bla(CTX-M-14). Downstream of bla(CTX-M) and bla(CTX-M-15) genes in the major bacterial isolates orf477 mucA and Delta orf477-Delta mucA sequences were detected respectively. Two isolates had additional Delta orf3 insertion inside of Delta orf477-Delta mucA sequence. Insertion sequence IS903 (intact or deleted) was detected downstream of bla(CTX-M-14) gene. Unlike the others, bla(CTX-M-2) and bla(CTX-M-9) genes were located inside of ISCR1 mobile element, downstream of class 1 integron and orf513 sequence.

[Creation of genomic DNA libraries for Pseudomonas mallei and Pseudomonas pseudomallei]. / Sozdanie bibliotek genomnoi DNK Pseudomonas mallei i Pseudomonas pseudomallei.

The genomic libraries of P. mallei and P. pseudomallei species were constructed in Escherichia coli. The chromosomal DNA of P. pseudomallei C-141 strain has been cloned into the cosmid vector pHC79 and the broad host range plasmid vector pES154. The chromosomal DNA of P. mallei [symbol: see text]-5 strain has been cloned into the plasmid vector pSUP202. The recombinant clones of the genomic libraries were screened by the enzyme-linked immunoadsorbent assay (ELISA) to detect the production of Pseudomonas antigens: 28 clones were positive. Twelve recombinant strains demonstrated specific antigenic determinants of P. mallei and P. pseudomallei by immunoblotting. Cloned proteins of P. mallei and P. pseudomallei have molecular weights from 30 to 70 kD. A new method for introducing foreign genes into Pseudomonas genomes is offered. P. mallei strains with the chromosomally integrated plasmids pSM are universal recipients for ColEI-based cloning vectors.

[Pseudomonas mallei and Pseudomonas pseudomallei: introduction and maintenance of natural and recombinant plasmid replicons]. / Pseudomonas mallei i Pseudomonas pseudomallei: vvedenie i podderzhanie prirodnykh i rekombinantnykh plazmidnykh replikonov.

Comparative analysis of recipient activity of Pseudomonas mallei, Pseudomonas pseudomallei, and Pseudomonas cepacia strains towards naturally occurring and recombinant plasmid replicons was carried out. Autonomic broad host range vector plasmids based on RSF1010(IncQ) and pSa(IncW) replicons as well as integrative vectors based on pSUP202(Co1E1) replicon have been constructed. The study has shown that naturally occurring plasmids RSF1010(IncQ), pSa(IncW), R15(IncN), and RP4(IncP) are being efficiently transferred and stably maintained in investigated Pseudomonas strains. However, recombinant plasmids with the mini-replicon pSa which are stable in Escherichia coli have shown segregative instability in Pseudomonas strains, whereas derivatives of plasmid RSF1010 demonstrated different stability depending on the type of insertion. Plasmid pSUP202 derivative integrative vector pSM525 is efficiently introduced and stably maintained in P. mallei C-5 strain. Two vector systems for genetic manipulations in P.mallei and P.pseudomallei cells have been developed.

[Integration of a plasmid into the Pseudomonas aeruginosa chromosome mediated by homologous DNA sequences]. / Integratsiia plazmid v khromosomu Pseudomonas aeruginosa za schet gomologichnykh poseldovatel'nostei DNK.

The integrative vectors for Pseudomonas aeruginosa cells were constructed on the basis of the plasmid pSUP202. To construct the integrative vectors the fragments of chromosomal DNA mediating the homologous recombination were cloned in the plasmid. The possibility of cloning of different genes in the chromosomes of Pseudomonas aeruginosa cells was illustrated by KmR gene cloning.

[Regulation of expression of the htpR gene in Escherichia coli]. / Reguliatsiia ékspressii gena htpR Escherichia coli.

The hybrid operon htpR: ATP was obtained, in which the expression of the aminoglycoside phosphotransferase gene is controlled by the promoter of the htpR gene of Escherichia coli. It was shown that the transcription of the htpR gene is not induced during the "heat shock". The basal level of the htpR gene transcription in htpR mutants was found to be two times higher than that in the strains of the "wild type". These findings suggested that the expression of the htpR gene is autoregulated. Hybridization experiments demonstrated that the genome of Pseudomonas bacteria contains the htpR-like gene.

Isolation and some properties of the site-specific endonuclease and methylase Bme2161 from Bacillus megaterium 216.

The site-specific endonuclease Bme2161 was isolated as a homogeneous preparation by chromatography on phosphocellulose, hydroxyapatite and heparin-agarose. The molecular mass of the enzyme, determined by gel filtration and by electrophoresis under denaturing conditions, was found to be 60 kDa and 30 kDa respectively. These data indicate that the native enzyme consists of two identical subunits. The enzyme recognized the decreases pentanucleotide sequence 5'-GGACC-3' X 3'-CCTGG-5' and cleaves the sequence as indicated by arrows. The increases optimal concentration for endonuclease reaction is 6-7 mM Mg2+. The endonuclease relaxes its specificity in the presence of glycerol or dimethyl sulfoxide at low Mg2+ concentration (1-3 mM). Methylase Bme2161, which protects DNA against endonuclease Bme2161 action by DNA methylation, was isolated from the same bacterial strain.

[Directed mutagenesis of chromosomal genes of Escherichia coli in vivo: construction of RecA- and HtpR- mutants]. / Napravlennyi mutagenez khromosomnykh genov Escherichia coli in vivo: konstruirovanie RecA- i HtpR- mutantov.

The deletions in Escherichia coli chromosomal genes recA and htpR were constructed using the site-directed mutagenesis techniques. The obtained RecA- mutants are UV-sensitive and have a phenotype defective for the homologous DNA recombination. HtpR- mutant is temperature sensitive for growth and deficient in intracellular proteolysis. As a result a HtpR- mutant seems to be a preferable candidate for attempting to synthesize efficiently any alien protein in Escherichia coli cells.

[Synthesis of aminoglycoside phosphotransferase is under control the PL-promoter of phage lambda]. / Sintez aminoglikozidfosfotransferazy pod kontrolem PL-promotora faga lambda.

The recombinant plasmid pKP145 PL has been constructed containing the gene for aminoglycosidephosphotransferase (APT). Expression of the APT gene is under the control of lambda bacteriophage PL promoter. Escherichia coli cells harbouring this plasmid synthesize APT in quantity up to 13-15% of the total cellular protein. The technique for isolation of APT from superproducing cells has been elaborated. Preparations of the enzyme devoid of contaminating bacterial proteins have been obtained.

[BbvII--a new site-specific endonuclease from Bacillus brevis 80]. / BbvII--novaia sait-spetsificheskaia éndonukleaza iz Bacillus brevis 80.

BbvII, a new site-specific endonuclease, has been isolated from Bacillus brevis 80 by gel-filtration and chromatography on heparin-Sepharose. The endonuclease recognizes a non-symmetrical sequence 5'-GTCTTC-3' in double-stranded DNA and cleaves DNA 3'-CAGAAG-5' in both strands outside the recognition sequence.

[Site-specific endonuclease BmeI from Bacillus megaterium 216]. / Sait-spetsificheskaia éndonukleaza BmeI iz Bacillus megaterium 216.

A site-specific endonuclease BmeI has been isolated from Bacillus megaterium 216 by gel filtration on ultragel AcA-44 with a subsequent chromatography on heparin-sepharose 6B. On the double-stranded DNA the endonuclease recognizes the pentanucleotide sequence (Formula: see text); and hydrolyzes it in the points shown by arrows. At gel filtration the endonuclease is eluted in the volume corresponding to a molecular mass of 60 000.