• Structural analysis of ligand-bound states of the Salmonella type III secretion system ATPase InvC.

      Bernal, Ivonne; Römermann, Jonas; Flacht, Lara; Lunelli, Michele; Uetrecht, Charlotte; Kolbe, Michael; CSSB, Centre for Structural Systembiologie, Notkestr.85, 22607 Hamburg. Germany. (Wiley, 2019-10-01)
      Translocation of virulence effector proteins through the type III secretion system (T3SS) is essential for the virulence of many medically relevant Gram‐negative bacteria. The T3SS ATPases are conserved components that specifically recognize chaperone–effector complexes and energize effector secretion through the system. It is thought that functional T3SS ATPases assemble into a cylindrical structure maintained by their N‐terminal domains. Using size‐exclusion chromatography coupled to multi‐angle light scattering and native mass spectrometry, we show that in the absence of the N‐terminal oligomerization domain the Salmonella T3SS ATPase InvC can form monomers and dimers in solution. We also present for the first time a 2.05 å resolution crystal structure of InvC lacking the oligomerization domain (InvCΔ79) and map the amino acids suggested for ATPase intersubunit interaction, binding to other T3SS proteins and chaperone–effector recognition. Furthermore, we validate the InvC ATP‐binding site by co‐crystallization of InvCΔ79 with ATPγS (2.65 å) and ADP (2.80 å). Upon ATP‐analogue recognition, these structures reveal remodeling of the ATP‐binding site and conformational changes of two loops located outside of the catalytic site. Both loops face the central pore of the predicted InvC cylinder and are essential for the function of the T3SS ATPase. Our results present a fine functional and structural correlation of InvC and provide further details of the homo‐oligomerization process and ATP‐dependent conformational changes underlying the T3SS ATPase activity.
    • Structural Basis for Designing Multiepitope Vaccines Against COVID-19 Infection: In Silico Vaccine Design and Validation.

      Srivastava, Sukrit; Verma, Sonia; Kamthania, Mohit; Kaur, Rupinder; Badyal, Ruchi Kiran; Saxena, Ajay Kumar; Shin, Ho-Joon; Kolbe, Michael; Pandey, Kailash C; CSSB, Centre for Structural Systembiologie, Notkestr.85, 22607 Hamburg. Germany. (: JMIR Publications Inc., 2020-06-19)
      Both designed MEVs are composed of CTL and HTL epitopes screened from 11 Open Reading Frame (ORF), structural and nonstructural proteins of the SARS-CoV-2 proteome. Both MEVs also carry potential B-cell linear and discontinuous epitopes as well as interferon gamma-inducing epitopes. To enhance the immune response of our vaccine design, truncated (residues 10-153) Onchocerca volvulus activation-associated secreted protein-1 was used as an adjuvant at the N termini of both MEVs. The tertiary models for both the designed MEVs were generated, refined, and further analyzed for stable molecular interaction with toll-like receptor 3. Codon-biased complementary DNA (cDNA) was generated for both MEVs and analyzed in silico for high level expression in a mammalian (human) host cell line.