The tail-specific protease (Tsp) of Chlamydiae spp.: Mechanistic and structural characterization of its interactions with host-cell proteins
Final Report Abstract
Chlamydia trachomatis is the most prevalent cause of preventable blindness worldwide and a major reason for infectious infertility in females. Several bacterial factors have been implicated in the pathogenesis of C. trachomatis. Combining structural and mutational analysis, we have shown that the proteolytic function of CT441 depends on a conserved Ser/Lys/Gln catalytic triad and a functional substrate-binding site within a flexible PDZ (postsynaptic density of 95 kDa, discs large, and zonula occludens) domain. Previously it has been suggested that CT441 is involved in modulating estrogen signaling responses of the host cell. Our results show that although in vitro CT441 exhibits proteolytic activity against SRAP1, a coactivator of estrogen receptor, CT441-mediated SRAP1 degradation is not observed during the intracellular developmental cycle before host cells are lysed and infectious Chlamydiae are released. Most compellingly, we have newly identified a chaperone activity of CT441, indicating a role of CT441 in prokaryotic protein quality control processes. The shed further light on protein-quality control processes in Chlamydiae, HtrA from S. negevensis (HtrASn) has been structurally and biochemically characterized. X-ray crystallographic structures show that PDZ domains of HtrASn enable self-compartmentalizing into 6-mers and 12-mers. Both crystal structures display a unique architecture among prokaryotic HtrA proteins which is mostly attributed to a different orientation and position of the PDZ2 domain. The 12-mer reveals two peptides bound to the PDZ1 domain and to the active site which show that, similar to other members of HtrA proteins, proteolytic activity of HtrASn is allosterically activated by substrate binding. The structures provide essential insights into stabilization of large oligomeric assemblies of chlamydial HtrAs and thereby represent a structural framework for rational development of future antichlamydial compounds.
Publications
- (2015) Production, crystallization and X-ray diffraction analysis of the protease CT441 from Chlamydia trachomatis. Acta Crystallogr F Struct Biol Commun 71(Pt 12): 1454-1458
Kohlmann F, Shima K, Rupp J, Solbach W, Hilgenfeld R, Hansen G
(See online at https://doi.org/10.1107/S2053230X15020518) - (2015) Structural basis of the proteolytic and chaperone activity of Chlamydia trachomatis CT441. J Bacteriol 197(1): 211-218
Kohlmann F, Shima K, Hilgenfeld R, Solbach W, Rupp J, Hansen G
(See online at https://doi.org/10.1128/JB.02140-14) - (2015) Strukturelle und funktionelle Charakterisierung der Protease CT441 aus Chlamydia trachomatis. Lübeck, Univ., Diss.
Kohlmann, F
