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Biology subjects

Hudson, A. J.

Publications and source records attributed to Hudson, A. J..

2 recordsLinked to original sources

FluoroTensor: identification and tracking of colocalised molecules and their stoichiometries in multi-colour single molecule imaging via deep learning.

The identification of photobleaching steps in single molecule fluorescence imaging is a well-established procedure for analysing the stoichiometries of molecular complexes. Nonetheless, the method is challenging with protein fluorophores because of the high levels of noise, rapid bleaching and very variable signal intensities, all of which complicate methods based on statistical analyses of intensities to identify bleaching steps. It has recently been shown that deep learning by convolutional neural networks can yield an accurate analysis with a relatively short computational time. We describe here an improved use of such an approach that detects bleaching events even in the first time point of observation, and we have included this within an integrated software package incorporating fluorescence spot detection, colocalisation, tracking, FRET and photobleaching step analyses of single molecules or complexes. This package, known as FluoroTensor, is written in Python with a self-explanatory user interface.

biophysics↗

Structural and biochemical insights into heterotetramer formation between human oncogenic K-Ras4BG12V and Rgl2, a RalA/B activator

About a quarter of total human cancers carry mutations in Ras isoforms. Accumulating evidence suggests that small GTPases, RalA and RalB, and their activators, Ral guanine nucleotide exchange factors (RalGEFs), play an essential role in oncogenic Ras-induced signalling. We studied the interaction between human KRas4B and the Ras association (RA) domain of Rgl2 (Rgl2RA), one of the RA-containing RalGEFs. We show that the G12V oncogenic KRas4B mutation changes the interaction kinetics with Rgl2RA. The crystal structure of the KRas4BG12V: Rgl2RA complex shows a 2:2 heterotetramer where the Switch I and Switch II regions of each KRasG12V interact with both Rgl2RA molecules. This structural arrangement is highly similar to the HRasE31K:RALGDSRA crystal structure and is distinct from the well-characterised Ras:Raf complex. Interestingly, the G12V mutation was found at the dimer interface of KRas4BG12V with its partner. Our study reveals a potentially distinct mode of Ras:effector complex formation by RalGEFs, and offers a possible mechanistic explanation for how the oncogenic KRas4BG12V hyperactivates the RalA/B pathway.

biochemistry↗