Biology subjects

Verdegaal, A. A.

Publications and source records attributed to Verdegaal, A. A..

3 recordsLinked to original sources

bioRxiv2019

Structure and function of a 9.6 megadalton bacterial iron storage compartment

Iron storage proteins are essential for maintaining intracellular iron homeostasis and redox balance. Iron is generally stored in a soluble and bioavailable form inside ferritin protein compartments. However, some organisms do not encode ferritins and thus rely on alternative storage strategies. Encapsulins, a class of protein-based organelles, have recently been implicated in microbial iron and redox metabolism. Here, we report the structural and mechanistic characterization of a 42 nm two-component encapsulin-based iron storage compartment from Quasibacillus thermotolerans. Using cryo-electron microscopy and x-ray crystallography, we reveal the assembly principles of a thermostable T = 4 shell topology and its catalytic ferroxidase cargo. We show that the cargo-loaded compartment has an exceptionally large iron storage capacity storing over 23,000 iron atoms. These results form the basis for understanding alternate microbial strategies for dealing with the essential element iron.

biochemistry↗

bioRxiv2018

Variability of bacterial behavior in the mammalian gut captured using a growth-linked single-cell synthetic gene oscillator

The dynamics of the bacterial population that comprises the gut microbiota plays key roles in overall mammalian health. However, a detailed understanding of bacterial growth within the gut is limited by the inherent complexity and inaccessibility of the gut environment. Here, we deploy an improved synthetic genetic oscillator to investigate dynamics of bacterial colonization and growth in the mammalian gut under both healthy and disease conditions. The synthetic oscillator, when introduced into both Escherichia coli and Salmonella Typhimurium maintains regular oscillations with a constant period in generations across growth conditions. We determine the phase of oscillation from individual bacteria using image analysis of resultant colonies and thereby infer the number of cell divisions elapsed. In doing so, we demonstrate robust functionality and controllability of the oscillator circuits activity during bacterial growth in vitro, in a simulated murine gut microfluidic environment, and in vivo within the mouse gut. We determine different dynamics of bacterial colonization and growth in the gut under normal and inflammatory conditions. Our results show that a precise genetic oscillator can function in a complex environment and reveal single cell behavior under diverse conditions where disease may create otherwise impossible-to-quantify variability in growth across the population.

synthetic biology↗

bioRxiv2018

Coordinated activity of sleep and arousal neurons for stabilizing sleep/wake states in Drosophila

The output arm of the sleep homeostat in Drosophila is a group of neurons with projections to the dorsal fan-shaped body (dFSB) of the central complex in the brain. However, neurons that regulate the sleep homeostat remain poorly understood. Using neurogenetic approaches combined with ex vivo Ca2+ imaging, we identify two groups of sleep-regulatory neurons that modulate the activity of the sleep homeostat in an opposing fashion. The sleep-promoting neurons activate the sleep homeostat with glutamate, whereas the arousal-promoting neurons down-regulate the sleep homeostat output with dopamine. Co-activating these two inputs leads to frequent shifts between sleep and wake states. We also show that dFSB sleep homeostat neurons release the neurotransmitter GABA that inhibits octopaminergic arousal neurons. Taken together, we suggest coordinated neuronal activity of sleep- and arousal-promoting neurons is essential for stabilizing sleep/wake states.

neuroscience↗