Title: Yeast glycolytic oscillations: experiments and detailed kinetic modelling of single cells and synchronised populations

Presenter: Prof. Jacky L. Snoep

University: Department of Biochemistry, Stellenbosch University, Stellenbosch, South Africa

Time: 9:00-11:00, November 21, 2014

Venue: Room A102, Institute of Microbiology, Chinese Academy of Sciences

Abstract: Oscillations are widely distributed in nature and have been studied at the level of individual oscillators (e.g. Calcium oscillations in excitable cells) and at the population level (e.g. phase synchronisation of firefly flashes at night). Yeast glycolysis is the best-known oscillatory system, although it has been studied almost exclusively at the population level. This limits these studies to observations of average behaviour in synchronized cultures, and makes it hard to distinguish the onset of synchronisation from the onset of oscillations. To make this distinction, we positioned individual yeast cells with optical tweezers in a microfluidic chamber (1) to determine the precise conditions for autonomous glycolytic oscillations (2), in a combined experimental and modelling approach.

Hopf bifurcation points were determined experimentally in individual cells via precise perturbations of glucose and cyanide concentrations. The experiments were analysed in a detailed mathematical model (3) and could be interpreted in terms of an oscillatory manifold in a three-dimensional state-space; crossing the boundaries of the manifold coincides with the onset of oscillations and positioning along the longitudinal axis of the volume sets the period. The oscillatory manifold could be approximated by allosteric control values of phosphofructokinase for ATP and AMP.

References:

1. Gustavsson A-K, et. al., (2012), FEBS J 279, 2837–2847.

2. Gustavsson A-K, et. al., (2014), FEBS J 281, 2784-2793

3. du Preez F, et. al., (2012), FEBS J 279, 2810–2822.