Cas13-containing type VI CRISPR-Cas systems specifically target RNA; however, the mechanism of spacer acquisition remains unclear. We have previously reported the association of reverse transcriptase-Cas1 (RT-Cas1) fusion proteins with certain types of VI-A systems. Here, we show that RT-Cas1 fusion proteins are also recruited by type VI-B systems in bacteria from gut microbiomes, constituting a VI-B1 variant system that includes a CorA-encoding locus in addition to the CRISPR array and the RT-Cas1/Cas2 adaptation module.
View Article and Find Full Text PDFLight-driven sodium pumps (NaRs) are unique ion-transporting microbial rhodopsins. The major group of NaRs is characterized by an NDQ motif and has two aspartic acid residues in the central region essential for sodium transport. Here we identify a subgroup of the NDQ rhodopsins bearing an additional glutamic acid residue in the close vicinity to the retinal Schiff base.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
November 2023
The temporal difference learning (TDL) algorithm has been essential to conceptualizing the role of dopamine in reinforcement learning (RL). Despite its theoretical importance, it remains unknown whether a neuronal implementation of this algorithm exists in the brain. Here, we provide an interpretation of the recently described signaling properties of ventral tegmental area (VTA) GABAergic neurons and show that a circuitry of these neurons implements the TDL algorithm.
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