Biology subjects

Bates, E.

Publications and source records attributed to Bates, E..

3 recordsLinked to original sources

bioRxiv2026

Non-homologous end-joining is implicated in rapid and efficient caspofungin adaptation in Nakaseomyces glabratus

Antifungal resistance in Nakaseomyces glabratus is a major clinical challenge, yet the cellular processes that shape its evolution remain poorly understood. Here, we used experimental evolution to investigate the role of the error-prone double-strand break repair pathway, non-homologous end joining (NHEJ), in adaptation to fluconazole and caspofungin. Wild-type and NHEJ-deficient (lig4{Delta}) populations were evolved under antifungal selection for 25 days. Fluconazole resistance emerged rapidly in both genetic backgrounds and was associated with recurrent PDR1 mutations and aneuploidies. In contrast, caspofungin adaptation was delayed and less efficient in lig4{Delta} populations, with several lineages failing to survive. All wild-type caspofungin-evolved isolates carried canonical FKS2 hotspot mutations, whereas lig4{Delta} isolates predominantly acquired resistance through alternative genetic pathways. Caspofungin adaptation also frequently conferred cross-resistance to fluconazole and was accompanied by changes in the abundance of ergosterol-associated proteins. Together, these findings implicate NHEJ in promoting efficient evolution of FKS-mediated echinocandin resistance and demonstrate that DNA repair capacity can shape antifungal resistance trajectories in N. glabratus.

microbiology↗

bioRxiv2025

Cryo-EM structure of a type VI secretion system delivered membrane-depolarizing toxin involved in bacterial antagonism

Many Gram-negative bacteria use type VI secretion systems (T6SSs) to deliver toxic effector proteins into neighboring competitor cells. Members of the VasX protein family, such as VasX from Vibrio cholerae and Tke5 from Pseudomonas putida, disrupt the inner membrane of target cells by forming ion-permeable channels that dissipate the proton motive force, thereby interfering with essential physiological processes. However, the molecular structure of any VasX family effector has remained unknown. Here, we present a cryo-EM structure of Ptx2, a recently identified VasX family effector exported by a T6SS of Pseudomonas aeruginosa. Our structure reveals that Ptx2 is an elongated, multi-domain protein that bears little resemblance to proteins of known function. Notably, the apparent flexibility of its domains suggests that Ptx2, like other membrane-depolarizing toxins, undergoes substantial conformational changes to facilitate membrane insertion. Guided by these predicted structural rearrangements, we used mutagenesis coupled with phenotypic assays to identify key features required for its toxic activity. Together, these findings provide the first molecular level insights into the structure and mechanism of VasX family effectors and expand our understanding of how these proteins contribute to interbacterial antagonism.

microbiology↗

bioRxiv2020

Common synaptic phenotypes arising from diverse mutations in the human NMDA receptor subunit GluN2A

Dominant mutations in the human gene GRIN2A, encoding NMDA receptor (NMDAR) subunit GluN2A, make a significant and growing contribution to the catalogue of published single-gene epilepsies. Understanding the disease mechanism in these epilepsy patients is complicated by the surprising diversity of effects that the mutations have on NMDARs. We have examined the cell-autonomous effect of five GluN2A mutations, 3 loss-of-function and 2 gain-of-function, on evoked NMDAR-mediated synaptic currents (NMDA-EPSCs) in CA1 pyramidal neurons in cultured hippocampal slices. Despite the mutants differing in their functional incorporation at synapses, prolonged NMDA-EPSC current decays (with only marginal changes in charge transfer) were a common effect for both gain- and loss-of-function mutants. Modelling NMDA-EPSCs with mutant properties in a CA1 neuron revealed that the effect of GRIN2A mutations can lead to abnormal temporal integration and spine calcium dynamics during trains of concerted synaptic activity. Investigations beyond establishing the molecular defects of GluN2A mutants are much needed to understand their impact on synaptic transmission.

neuroscience↗