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Pseudomonas aeruginosa ParA belongs to a large subfamily of Walker-type ATPases acting as partitioning proteins in bacteria. ParA has the ability to both self-associate and interact with its partner ParB. Analysis of the deletion mutants defined the part of the protein involved in dimerization and interactions with ParB. Here, a set of ParA alanine substitution mutants in the region between E67 and L85 was created and analysed in vivo and in vitro. All mutants impaired in dimerization (substitutions at positions M74, H79, Y82 and L84) were also defective in interactions with ParB, suggesting that ParA-ParB interactions depend on the ability of ParA to dimerize. Mutants with alanine substitutions at positions E67, C68, L70, E72, F76, Q83 and L85 were not impaired in dimerization, but were defective in interactions with ParB. The dimerization interface partly overlapped the pseudo-hairpin, involved in interactions with ParB. ParA mutant derivatives tested in vitro showed no defects in ATPase activity. Two parA alleles (parA84, whose product can neither self-interact nor interact with ParB, and parA67, whose product is impaired in interactions with ParB, but not in dimerization) were introduced into the P. aeruginosa chromosome by homologous gene exchange. Both mutants showed defective separation of ParB foci, but to different extents. Only PAO1161 parA84 was visibly impaired in terms of chromosome segregation, growth rate and motility, similar to a parA-null mutant., (© 2014 The Authors.)

Influenza is a contagious respiratory disease caused by viruses belonging to the family Ortomyxoviridae. Among the influenza viruses type A, B and C, the A type virus shows the most pathogenic potential. Its surface receptor glycoproteins, hemagglutinin (HA) and neuraminidase (NA), are characterized by high antigenic variation, thus a host organism cannot develop permanent resistance. The case is described of a male patient with severe acute respiratory distress syndrome in the course of influenza A/N1H1v infection, confirmed by virological molecular analysis. During diagnostic procedures based on the MSSCP genotyping it was observed that the WHO recommended RT-PCR kits and/or procedure of sample collection from patients for molecular investigation could lead to false positive A/H1N1 pandemic strain detection because of the co-amplification during the RT-PCR fragments of the human genome.

Introduction: In the autumn of 2009 the authors participated in a humanitarian operation in Western Ukraine by undertaking an epidemiological investigation of an influenza-like-illness (ILI) in the L'viv Oblast region. Mobile biological survey teams took samples from civilian patients with severe acute respiratory distress syndrome, rapid transportation of the samples, and their molecular analysis in Poland to provide accurate results., Objective: The aim of the study was the molecular and epidemiological analysis of the biological samples collected., Material and Methods: Real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR), multiplex PCR techniques, traditional Sanger Sequencing and classical viral culture methods were used., Results: Among the 124 influenza-like illness cases, ~50% (58) were positive for influenza A virus in WHO-CDC molecular assay, including subtyping. The specimens were further analyzed to confirm results and determine the genetic sequence. Phylogenetically, the nucleotide similarity of both the Ukraine specimens and reference A/California/7/2009 (pH1N1) was 99.2-99.3%. Oseltamivir resistance was not registered. HA1 region characterization showed an overall protein identity of 98.5-99.4%., Conclusions: An unexpected high contribution of influenza A was confirmed among ILI patients, as well as a very limited number of other detected viruses, indicate that the 2009 epidemic in western Ukraine was strongly related to novel influenza A/H1N1. The importance of swift sharing of information and reference laboratories networking in surveillance, as well as serving governments and international agencies in pursuing adequate actions, should be stressed.

The parA and parB genes of Pseudomonas aeruginosa are located approximately 8 kb anticlockwise from oriC. ParA is a cytosolic protein present at a level of around 600 molecules per cell in exponential phase, but the level drops about fivefold in stationary phase. Overproduction of full-length ParA or the N-terminal 85 amino acids severely inhibits growth of P. aeruginosa and P. putida. Both inactivation of parA and overexpression of parA in trans in P. aeruginosa also lead to accumulation of anucleate cells and changes in motility. Inactivation of parA also increases the turnover rate (degradation) of ParB. This may provide a mechanism for controlling the level of ParB in response to the growth rate and expression of the parAB operon.

The par genes of Pseudomonas aeruginosa have been studied to increase the understanding of their mechanism of action and role in the bacterial cell. Key properties of the ParB protein have been identified and are associated with different parts of the protein. The ParB- ParB interaction domain was mapped in vivo and in vitro to the C-terminal 56 amino acids (aa); 7 aa at the C terminus play an important role. The dimerization domain of P. aeruginosa ParB is interchangeable with the dimerization domain of KorB from plasmid RK2 (IncP1 group). The C-terminal part of ParB is also involved in ParB-ParA interactions. Purified ParB binds specifically to DNA containing a putative parS sequence based on the consensus sequence found in the chromosomes of Bacillus subtilis, Pseudomonas putida, and Streptomyces coelicolor. The overproduction of ParB was shown to inhibit the function of genes placed near parS. This "silencing" was dependent on the parS sequence and its orientation. The overproduction of P. aeruginosa ParB or its N-terminal part also causes inhibition of the growth of P. aeruginosa and P. putida but not Escherichia coli cells. Since this inhibitory determinant is located well away from ParB segments required for dimerization or interaction with the ParA counterpart, this result may suggest a role for the N terminus of P. aeruginosa ParB in interactions with host cell components.