Environmental Calcium Controls Alternate Physical States of the Caulobacter Surface Layer
Abstract
Surface layers (S-layers) are paracrystalline, proteinaceous structures found in most archaea and many bacteria. Often the outermost cell envelope component, S-layers serve diverse functions including aiding pathogenicity and protecting against predators. We report that the S-layer of Caulobacter crescentus exhibits calcium-mediated structural plasticity, switching irreversibly between an amorphous aggregate state and the crystalline state. This finding invalidates the common assumption that S-layers serve only as static wall-like structures. In vitro, the Caulobacter S-layer protein, RsaA, enters the aggregate state at physiological temperatures and low divalent calcium ion concentrations. At higher concentrations, calcium ions stabilize monomeric RsaA, which can then transition to the two-dimensional crystalline state. Caulobacter requires micromolar concentrations of calcium for normal growth and development. Without an S-layer, Caulobacter is even more sensitive to changes in environmental calcium concentration. Therefore, this structurally dynamic S-layer responds to environmental conditions as an ion sensor and protects Caulobacter from calcium deficiency stress, a unique mechanism of bacterial adaptation. These findings ...Continue Reading
References
Factors controlling in vitro recrystallization of the Caulobacter crescentus paracrystalline S-layer
Citations
Methods Mentioned
Software Mentioned
Related Concepts
Related Feeds
BioHub - Researcher Network
The Chan-Zuckerberg Biohub aims to support the fundamental research and develop the technologies that will enable physicians to cure, prevent, or manage all diseases in our childrens' lifetimes. The CZ Biohub brings together researchers from UC Berkeley, Stanford, and UCSF. Find the latest research from the CZ Biohub researcher network here.