Skp is a multivalent chaperone of outer membrane proteins

The trimeric chaperone Skp sequesters outer-membrane proteins (OMPs) within a hydrophobic cage, thereby preventing their aggregation during transport across the periplasm in Gram-negative bacteria. Here, we studied the interaction between Escherichia coli Skp and five OMPs of varying size. Investigations of the kinetics of OMP folding revealed that higher Skp/OMP ratios are required to prevent the folding of 16-stranded OMPs compared with their 8-stranded counterparts. Ion mobility spectrometry–mass spectrometry (IMS–MS) data, computer modeling and molecular dynamics simulations provided evidence that 10- to 16-stranded OMPs are encapsulated within an expanded Skp substrate cage. For OMPs that cannot be fully accommodated in the expanded cavity, sequestration is achieved by binding of an additional Skp trimer. The results suggest a new mechanism for Skp chaperone activity involving the coordination of multiple copies of Skp in protecting a single substrate from aggregation

Outer membrane protein folding from an energy landscape perspective

The cell envelope is essential for the survival of Gram-negative bacteria. This specialised membrane is densely packed with outer membrane proteins (OMPs), which perform a variety of functions. How OMPs fold into this crowded environment remains an open question. Here, we review current knowledge about OFMP folding mechanisms in vitro and discuss how the need to fold to a stable native state has shaped their folding energy landscapes. We also highlight the role of chaperones and the β-barrel assembly machinery (BAM) in assisting OMP folding in vivo and discuss proposed mechanisms by which this fascinating machinery may catalyse OMP folding

LAB-Secretome: a genome-scale comparative analysis of the predicted extracellular and surface-associated proteins of Lactic Acid Bacteria.

Contains fulltext : 87861.pdf (publisher's version ) (Open Access

Resilience and critical infrastructure: origins, theories and critiques

This chapter maps the intersection and imbrication of two objects – critical infrastructure (CI) – and then, resilience – over the last decade or so. In so doing, our purpose is to examine what making critical infrastructure resilient might variously mean, whether to governments, infrastructure operators, or diverse publics; and by the same token, how has accepting that resilience is infrastructural altered notions of resilience? Our discussions across this chapter are drawn from two closely related bodies of literature. The first critically examines the political framings of varied notions of resilience, while the second looks at how infrastructural materialities and circulations mediate certain conditions of life and their political imaginings. In bridging these literatures, we would also like to draw particular attention to how certain notions of resilience, notably those deemed ‘neoliberal’ are being exposed, challenged, and even multiplied, through their circulation within the materialities of critical infrastructure