The innate immune response to Streptococcus pneumoniae in the lung is influenced by immunoproteasomes

The ubiquitin-proteasome system is responsible for degradation of most intracellular proteins and consists of two steps: ubiquitination and proteasome-mediated degradation. The proteasome is a large protease composed of multiple subunits that is present in all eukaryotic cells and is essential for many basic cellular processes such as protein homeostasis, cell growth and antigen presentation. Following infection and subsequent IFN-γ release, three proteasome subunits are replaced by the inducible subunits LMP7, LMP2 and MECL1, producing immunoproteasome (IP). The observation that IP are constitutively present in…