BackgroundIn the genome of H. pylori 26695, 149 proteins containing the CXXC motif characteristic of thioldisulfide oxidoreductases have been identified to date. However, only two of these proteins have a thioredoxin-like fold (i.e., HP0377 and HP0231) and are periplasm-located. We have previously shown that HP0231 is a dimeric oxidoreductase that catalyzes disulfide bond formation in the periplasm. Although HP0377 was originally described as DsbC homologue, its resolved structure and location of the hp0377 gene in the genome indicate that it is a counterpart of CcmG/DsbE.ResultsThe present work shows that HP0377 is present in H. pylori cells only in a reduced form and that absence of the main periplasmic oxidase HP0231 influences its redox state. Our biochemical analysis indicates that HP0377 is a specific reductase, as it does not reduce insulin. However, it possesses disulfide isomerase activity, as it catalyzes the refolding of scrambled RNase. Additionally, although its standard redox potential is -176 mV, it is the first described CcmG protein having an acidic pKa of the N-terminal cysteine of the CXXC motif, similar to E. coli DsbA or E. coli DsbC. The CcmG proteins that play a role in a cytochrome c-maturation, both in system I and system II, are kept in the reduced form by an integral membrane protein DsbD or its analogue, CcdA. In H. pylori HP0377 is re-reduced by CcdA (HP0265); however in E. coli it remains in the oxidized state as it does not interact with E. coli DsbD. Our in vivo work also suggests that both HP0377, which plays a role in apocytochrome reduction, and HP0378, which is involved in heme transport and its ligation into apocytochrome, provide essential functions in H. pylori.ConclusionsThe present data, in combination with the resolved three-dimensional structure of the HP0377, suggest that HP0377 is an unusual, multifunctional CcmG protein.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0471-z) contains supplementary material, which is available to authorized users.

In 2003-04 first five VIM-2 metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa (MPPA) isolates with an In4-like integron In461 (aadB–blaVIM-2–aadA6) on conjugative plasmids were identified in three hospitals in Poland. In 2005-15 MPPA much expanded in the country, and as many as 80 isolates in a collection of 454 MPPA (∼18%) had In461, being one of two most common MBL-encoding integrons. The organisms occurred in 49 hospitals in 33 cities of 11/16 main administrative regions. PFGE and MLST classified them into 55 pulsotypes and 35 STs, respectively, revealing their remarkable genetic diversity overall, with only a few small clonal clusters. The S1 nuclease/hybridization assays and mating of 63 representative isolates showed that ∼85% of these had large In461-carrying plasmids of ∼350-550 kb, usually self-transmitting with high efficiency (∼10−1-10−2 per donor cell). The plasmids from 19 isolates were sequenced, and subjected to structural and SNP-based phylogenetic analysis. These formed a subgroup within a family of IncP-2-type megaplasmids, observed worldwide in pseudomonads from various environments and conferring resistance/tolerance to multiple stress factors, including antibiotics. Their microdiversity in Poland arose mainly from acquisition of different accessory fragments, as well as new resistance genes and multiplication of these. Short-read sequence and/or PCR mapping confirmed the In461-carrying plasmids in the remaining isolates to be the IncP-2 types. The study demonstrated a large-scale epidemic spread of multi-drug resistance plasmids in P. aeruginosa populations, creating an epidemiological threat. It contributes to the knowledge on IncP-2 types, which are interesting research objects in resistance epidemiology, environmental microbiology and biotechnology.

GES-type extended-spectrum β-lactamases (ESBLs), like GES-1, mutate by Gly170Asn/Ser substitutions into carbapenem-hydrolyzing variants, of which GES-5 is relatively more frequent (1, 2).…

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Even though OXA-48/181 producers seem to occur infrequently in Poland, their epidemiology has been marked by various phenomena, namely multiple imports, several limited transmissions plus one larger clonal outbreak, and possible plasmid transfers.

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Objectives To identify key factors of the expansion of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa (MPPA) in Poland, focusing on the role of clonal epidemic(s). Methods MPPA isolates were typed by PFGE, followed by MLST. blaVIM/IMP MBL genes were amplified and sequenced within class 1 integrons. Their location was assessed by S1 nuclease-hybridization assays. Short-read WGS was performed, and genomes were subjected to SNP-based phylogenetic and resistome analyses. Results Of 1314 MPPA isolates collected in 2005–15 from 212 hospitals, 454 representatives were selected. The isolates belonged to 120 pulsotypes and 52 STs, of which ST235 (∼31%), ST111 (∼17%), ST273 (∼16%) and ST654 (∼9%) prevailed, followed by ST244, ST17, ST395, ST175 and ST1567. The isolates produced seven VIM variants (97.5%) and four IMPs encoded by 46 integrons, most of which were observed only or mainly in Poland. Around 60% of the isolates resulted from (inter)regional clonal outbreaks of 10 individual ST235, ST111, ST273 and ST654 genotypes. The phylogenetic analysis of 163 genomes revealed heterogeneity of ST235 and ST111 populations, arising from transnational circulation and on-site differentiation of several clades/branches. Contrarily, ST273 and ST654 formed relatively homogeneous and apparently Poland-specific lineages, and a unique ST273 genotype with integron In249 was the most expansive organism. Conclusions Together with a previous report on self-transmissible In461-carrying IncP-2-type plasmids, this study revealed the molecular/genomic background of the rapid MPPA increase in Poland in 2001–15, evidencing multi-clonal spread as its leading factor. Numerous novel/specific MPPA characteristics were identified.

The study confirmed the high genetic diversity of the collection of K. oxytoca ESC-non-susceptible isolates, composed of phylogroups with distinct types of OXY-type β-lactamases, and revealed some STs of broad geographical distribution.