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Structural analysis of the partially disordered protein EspK from Mycobacterium tuberculosis

DOI: 10.3390/cryst11010018 DOI Help

Authors: Abril Gijsbers (Maastricht University) , Nuria Sánchez-Puig (Maastricht University; Universidad Nacional Autónoma de México) , Ye Gao (Maastricht University) , Peter J. Peters (Maastricht University) , Raimond B. G. Ravelli (Maastricht University) , Dritan Siliqi (Istituto di Cristallografia, Consiglio Nazionale delle Ricerche)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystals , VOL 11

State: Published (Approved)
Published: December 2020
Diamond Proposal Number(s): 21741 , 21035

Open Access Open Access

Abstract: For centuries, tuberculosis has been a worldwide burden for human health, and gaps in our understanding of its pathogenesis have hampered the development of new treatments. ESX-1 is a complex machinery responsible for the secretion of virulence factors that manipulate the host response. Despite the importance of these secreted proteins for pathogenicity, only a few of them have been structurally and functionally characterised. Here, we describe a structural study of the ESX-secretion associated protein K (EspK), a 74 kDa protein known to be essential for the secretion of other substrates and the cytolytic effects of ESX-1. Small-Angle X-ray Scattering (SAXS) data show that EspK is a long molecule with a maximal dimension of 228 Å. It consists of two independent folded regions at each end of the protein connected by a flexible unstructured region driving the protein to coexist as an ensemble of conformations. Limited proteolysis identified a 26 kDa globular domain at the C-terminus of the protein consisting of a mixture of α-helices and β-strands, as shown by circular dichroism (CD) and SAXS. In contrast, the N-terminal portion is mainly helical with an elongated shape. Sequence conservation suggests that this architecture is preserved amongst the different mycobacteria species, proposing specific roles for the N- and C-terminal domains assisted by the middle flexible linker.

Journal Keywords: disordered region; EspK; ESX-1; SAXS

Diamond Keywords: Tuberculosis (TB); Bacteria

Subject Areas: Biology and Bio-materials

Instruments: B21-High Throughput SAXS

Other Facilities: P12-EMBL at DESY

Added On: 04/01/2021 11:16


Discipline Tags:

Life Sciences & Biotech Health & Wellbeing Infectious Diseases Pathogens Structural biology Chemistry Biochemistry

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)