ABSTRACT
The outer membrane of Gram-negative bacteria acts as an initial diffusion barrier that shields the cell from the environment. It contains many membrane-embedded proteins required for functionality of this system. These proteins serve as solute and lipid transporters or as machines for membrane insertion or secretion of proteins. The genome of Anabaena sp. strain PCC 7120 codes for two outer membrane transporters termed TpsB1 and TpsB2. They belong to the family of the two-partner secretion system proteins which are characteristic of pathogenic bacteria. Because pathogenicity of Anabaena sp. strain PCC 7120 has not been reported, the function of these two cyanobacterial TpsB proteins was analyzed. TpsB1 is encoded by alr1659, while TpsB2 is encoded by all5116 The latter is part of a genomic region containing 11 genes encoding TpsA-like proteins. However, tpsB2 is transcribed independently of a tpsA gene cluster. Bioinformatics analysis revealed the presence of at least 22 genes in Anabaena sp. strain PCC 7120 putatively coding for substrates of the TpsB system, suggesting a rather global function of the two TpsB proteins. Insertion of a plasmid into each of the two genes resulted in altered outer membrane integrity and antibiotic resistance. In addition, the expression of genes coding for the Clp and Deg proteases is dysregulated in these mutants. Moreover, for two of the putative substrates, a dependence of the secretion on functional TpsB proteins could be confirmed. We confirm the existence of a two-partner secretion system in Anabaena sp. strain PCC 7120 and predict a large pool of putative substrates.IMPORTANCE Cyanobacteria are important organisms for the ecosystem, considering their contribution to carbon fixation and oxygen production, while at the same time some species produce compounds that are toxic to their environment. As a consequence, cyanobacterial overpopulation might negatively impact the diversity of natural communities. Thus, a detailed understanding of cyanobacterial interaction with the environment, including other organisms, is required to define their impact on ecosystems. While two-partner secretion systems in pathogenic bacteria are well known, we provide a first description of the cyanobacterial two-partner secretion system.
Subject(s)
Anabaena/genetics , Anabaena/metabolism , Bacterial Outer Membrane Proteins/genetics , Bacterial Outer Membrane Proteins/metabolism , Gram-Negative Bacteria/metabolism , Anabaena/growth & development , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacterial Secretion Systems/genetics , Bacterial Secretion Systems/metabolism , Biological Transport , Cyanobacteria , Drug Resistance, Microbial , Gene Expression Regulation, Bacterial , Genome, Bacterial , Glucosyltransferases , Membrane Transport Proteins/genetics , Type V Secretion Systems/metabolismABSTRACT
OBJECTIVE: The goal of the present study was to estimate the treatment costs in immune-mediated rheumatic disease patients initiating treatment with an s.c. biologic agent based on treatment persistence. METHODS: This is a retrospective cohort study based on the German statutory health insurance funds database. Patients ⩾18 years of age with a diagnosis of AS, PsA or RA treated with s.c. TNF-α inhibitors (TNFis) were included. Persistence was estimated as the duration of time from s.c. TNFi therapy initiation to discontinuation, which was defined as at least 60 days without therapy. We performed 1:1 matching based on a propensity score that was constructed as the conditional probability of being persistent as a function of age, gender, index year, physician specialty and Charlson comorbidity index. Finally, the cost differences between the matched pairs were estimated using the Wilcoxon test. RESULTS: After 1:1 matching, 678 persistent and 678 non-persistent patients were available for cost analyses. Using a 2-year time period, the costs for office-based visits per patient were 2319 in the persistent cohort compared with 3094 in the non-persistent cohort (P < 0.001). Co-medication costs were 2828 in the persistent cohort compared with 5498 in the non-persistent cohort, hospitalization costs were 3551 in the persistent cohort compared with 5890 in the non-persistent cohort and sick leave costs were 717 in the persistent cohort compared with 1241 in the non-persistent cohort (all P < 0.001). CONCLUSION: The results of this study indicate that persistence with s.c. TNFi treatment can be associated with several cost offsets for immune-mediated rheumatic disease patients.
