High-Resolution Crystal Structure of RpoS Fragment including a Partial Region 1.2 and Region 2 from the Intracellular Pathogen Legionella pneumophila

Legionella pneumophila RpoS (LpRpoS) is an alternative sigma factor of RNA polymerase (RNAP) essential for virulence and stress resistance. To investigate the mechanism of RpoS in the intracellular pathogen L. pneumophila, we determined the high-resolution crystal structure of the LpRpoS (residues 95-194) containing a partial region 1.2 and region 2. The structure of LpRpoS (residues 95-194) reveals that the conserved residues are critical for promoter melting, DNA and core RNAP binding. The differences in regulatory factor binding site between Escherichia coli RpoS and LpRpoS suggest that LpRpoS may employ a distinct mechanism to recruit alternative regulatory factors controlling transcription initiation.

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Molecular mechanism for the subversion of the retromer coat by theLegionellaeffector RidL

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1715361115 ◽

2017 ◽

Vol 114 (52) ◽

pp. E11151-E11160 ◽

Cited By ~ 20

Author(s):

Miguel Romano-Moreno ◽

Adriana L. Rojas ◽

Chad D. Williamson ◽

David C. Gershlick ◽

María Lucas ◽

...

Keyword(s):

Crystal Structure ◽

Protein Interactions ◽

Legionella Pneumophila ◽

Molecular Mimicry ◽

Microbial Pathogens ◽

Intracellular Pathogen ◽

Hairpin Loop ◽

Domain Family ◽

Ankyrin Repeat Protein ◽

Endosomal Membranes

Microbial pathogens employ sophisticated virulence strategies to cause infections in humans. The intracellular pathogenLegionella pneumophilaencodes RidL to hijack the host scaffold protein VPS29, a component of retromer and retriever complexes critical for endosomal cargo recycling. Here, we determined the crystal structure ofL. pneumophilaRidL in complex with the human VPS29–VPS35 retromer subcomplex. A hairpin loop protruding from RidL inserts into a conserved pocket on VPS29 that is also used by cellular ligands, such as Tre-2/Bub2/Cdc16 domain family member 5 (TBC1D5) and VPS9-ankyrin repeat protein for VPS29 binding. Consistent with the idea of molecular mimicry in protein interactions, RidL outcompeted TBC1D5 for binding to VPS29. Furthermore, the interaction of RidL with retromer did not interfere with retromer dimerization but was essential for association of RidL with retromer-coated vacuolar and tubular endosomes. Our work thus provides structural and mechanistic evidence into how RidL is targeted to endosomal membranes.

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High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106478 ◽

1988 ◽

Vol 46 ◽

pp. 882-883

Author(s):

H.-J. Ou ◽

J. M. Cowley

Keyword(s):

Crystal Structure ◽

High Resolution ◽

Grain Boundary ◽

Strong Field ◽

Imaging Study ◽

Structure Defects ◽

High Tc ◽

High Tc Superconductor ◽

Diffraction Patterns ◽

Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

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