Partial complementation of Sinorhizobium meliloti bacA mutant phenotypes by the Mycobacterium tuberculosis BacA protein

The Sinorhizobium meliloti BacA ABC transporter protein plays an important role in its nodulating symbiosis with the legume alfalfa (Medicago sativa). The Mycobacterium tuberculosis BacA homolog was found to be important for the maintenance of chronic murine infections, yet its in vivo function is unknown. In the legume plant as well as in the mammalian host, bacteria encounter host antimicrobial peptides (AMPs). We found that the M. tuberculosis BacA protein was able to partially complement the symbiotic defect of an S. meliloti BacA-deficient mutant on alfalfa plants and to protect this mutant in vitro from the antimicrobial activity of a synthetic legume peptide, NCR247, and a recombinant human \u3b2-defensin 2 (HBD2). This finding was also confirmed using an M. tuberculosis insertion mutant. Furthermore, M. tuberculosis BacA-mediated protection of the legume symbiont S. meliloti against legume defensins as well as HBD2 is dependent on its attached ATPase domain. In addition, we show that M. tuberculosis BacA mediates peptide uptake of the truncated bovine AMP, Bac71-16. This process required a functional ATPase domain. We therefore suggest that M. tuberculosis BacA is important for the transport of peptides across the cytoplasmic membrane and is part of a complete ABC transporter. Hence, BacA-mediated protection against host AMPs might be important for the maintenance of latent infections

Tendências da investigação científica nas ciências da informação e documentação em Portugal: 2003-2018

This paper aims to present an analysis on the research carried out in Portugal regarding the academic works approved in the 2nd and 3rd cycles of studies in higher education in Portugal. We used the quantitative method, with an analysis of the graduated works in Information and Documentation Sciences, in a total of 699 works between 2003 and 2018. An analysis was made of the total of the theses and dissertations approved, per year and per institution, subject distribution according to the categories considered and the research methods used. The variation of the educational offer over the years has consequences in the number of works presented, however the tendency is for the majority of the works to be about Libraries, with emphasis on the School Libraries and the most used method of investigation is the qualitative metho