14 research outputs found
Single Enzyme Studies Reveal the Existence of Discrete Functional States for Monomeric Enzymes and How They Are “Selected” upon Allosteric Regulation
Energies and Dynamics of Ca2+/MG2+-Mediated Vesicle Docking, Measured using Single Particle Tracking
Domains of increased thickness in microvillar membranes of the small intestinal enterocyte
Recommended from our members
A structural analysis of M protein in coronavirus assembly and morphology.
The M protein of coronavirus plays a central role in virus assembly, turning cellular membranes into workshops where virus and host factors come together to make new virus particles. We investigated how M structure and organization is related to virus shape and size using cryo-electron microscopy, tomography and statistical analysis. We present evidence that suggests M can adopt two conformations and that membrane curvature is regulated by one M conformer. Elongated M protein is associated with rigidity, clusters of spikes and a relatively narrow range of membrane curvature. In contrast, compact M protein is associated with flexibility and low spike density. Analysis of several types of virus-like particles and virions revealed that S protein, N protein and genomic RNA each help to regulate virion size and variation, presumably through interactions with M. These findings provide insight into how M protein functions to promote virus assembly
Single Enzyme Studies Reveal the Existence of Discrete Functional States for Monomeric Enzymes and How They Are “Selected” upon Allosteric Regulation
Allosteric regulation of enzymatic activity forms the
basis for
controlling a plethora of vital cellular processes. While the mechanism
underlying regulation of multimeric enzymes is generally well understood
and proposed to primarily operate via conformational selection, the
mechanism underlying allosteric regulation of monomeric enzymes is
poorly understood. Here we monitored for the first time allosteric
regulation of enzymatic activity at the single molecule level. We
measured single stochastic catalytic turnovers of a monomeric metabolic
enzyme (<i>Thermomyces lanuginosus Lipase</i>) while titrating
its proximity to a lipid membrane that acts as an allosteric effector.
The single molecule measurements revealed the existence of discrete
binary functional states that could not be identified in macroscopic
measurements due to ensemble averaging. The discrete functional states
correlate with the enzyme’s major conformational states and
are redistributed in the presence of the regulatory effector. Thus,
our data support allosteric regulation of monomeric enzymes to operate
via selection of preexisting functional states and not via induction
of new ones