The newly published paper by the Virus-X team in the structural biology section of Acta Crystallographica was featured on the cover of the November 2019 issue of the journal. The structural analysis of the Bacillus subtilis PBSX prophage lytic cassette protein XepA described in the paper suggests that XepA may interact with the cytoplasmic membrane to facilitate cell lysis.
Crystal structures of the Bacillus subtilis prophage lytic cassette proteins XepA and YomS. Stefanie Freitag-Pohl, Andrius Jasilionis, Maria Håkansson, L. Anders Svensson, Rebeka Kovačič, Martin Welin, Hildegard Watzlawick, Lei Wang, Josef Altenbuchner, Magdalena Płotka, Anna Karina Kaczorowska, Tadeusz Kaczorowski, Eva Nordberg Karlsson, Salam Al-Karadaghi, Björn Walse, Arnthór Aevarsson and Ehmke Pohl. Acta Cryst. Section D Vol 75: 1028-1039. 2019.
Abstract: As part of the Virus-X Consortium that aims to identify and characterize novel proteins and enzymes from bacteriophages and archaeal viruses, the genes of the putative lytic proteins XepA from Bacillus subtilis prophage PBSX and YomS from prophage SPβ were cloned and the proteins were subsequently produced and functionally characterized. In order to elucidate the role and the molecular mechanism of XepA and YomS, the crystal structures of these proteins were solved at resolutions of 1.9 and 1.3 Å, respectively. XepA consists of two antiparallel β-sandwich domains connected by a 30-amino-acid linker region. A pentamer of this protein adopts a unique dumbbell-shaped architecture consisting of two discs and a central tunnel. YomS (12.9 kDa per monomer), which is less than half the size of XepA (30.3 kDa), shows homology to the C-terminal part of XepA and exhibits a similar pentameric disc arrangement. Each β-sandwich entity resembles the fold of typical cytoplasmic membrane-binding C2 domains. Only XepA exhibits distinct cytotoxic activity in vivo, suggesting that the N-terminal pentameric domain is essential for this biological activity. The biological and structural data presented here suggest that XepA disrupts the proton motive force of the cytoplasmatic membrane, thus supporting cell lysis.
Read the paper on the journal website here