Structural determinants of the interaction between influenza A virus matrix protein M1 and lipid membranes.

Influenza A virus is a pathogen responsible for severe seasonal epidemics threatening human and animal populations every year. One of the ten major proteins encoded by the viral genome, the matrix protein M1, is abundantly produced in infected cells and plays a structural role in determining the morphology of the virus. During assembly of new viral particles, M1 is recruited to the host cell membrane where it associates with lipids and other viral proteins. The structure of M1 is only partially known. In particular, structural details of M1 interactions with the cellular plasma membrane as well as M1-protein interactions and multimerization have not been clarified, yet. In this work, we employed a set of complementary experimental and theoretical tools to tackle these issues. Using raster image correlation, surface plasmon resonance and circular dichroism spectroscopies, we quantified membrane association and oligomerization of full-length M1 and of different genetically engineered M1 constructs (i.e., N- and C-terminally truncated constructs and a mutant of the polybasic region, residues 95-105). Furthermore, we report novel information on structural changes in M1 occurring upon binding to membranes. Our experimental results are corroborated by an all-atom model of the full-length M1 protein bound to a negatively charged lipid bilayer.

In-depth characterization of bacterial and archaeal communities present in the abandoned Kettara pyrrhotite mine tailings (Morocco).

In Morocco, pollution caused by closed mines continues to be a serious threat to the environment, like the generation of acid mine drainage. Mine drainage is produced by environmental and microbial oxidation of sulfur minerals originating from mine wastes. The fundamental role of microbial communities is well known, like implication of Fe-oxidizing and to a lesser extent S-oxidizing microorganism in bioleaching. However, the structure of the microbial communities varies a lot from one site to another, like diversity depends on many factors such as mineralogy, concentration of metals and metalloids or pH, etc. In this study, prokaryotic communities in the pyrrhotite-rich tailings of Kettara mine were characterized using the Illumina sequencing. In-depth phylogenetic analysis revealed a total of 12 phyla of bacteria and 1 phyla of Archaea. The majority of sequences belonged to the phylum of Proteobacteria and Firmicutes with a predominance of Bacillus, Pseudomonas or Corynebacterium genera. Many microbial populations are implicated in the iron, sulfur and arsenic cycles, like Acidiferrobacter, Leptospirillum, or Alicyclobacillus in Fe; Acidiferrobacter and Sulfobacillus in S; and Bacillus or Pseudomonas in As. This is one of the first description of prokaryotic communities in pyrrhotite-rich mine tailings using high-throughput sequencing.