The pathway to resolve dimeric forms distinguishes plasmids from megaplasmids in Enterobacteriaceae.

Bacterial genomes contain a plethora of secondary replicons of divergent size. Circular replicons must carry a system for resolving dimeric forms, resulting from recombination between sister copies. These systems use site-specific recombinases.

Mitochondria- and ER-associated actin are required for mitochondrial fusion.

Mitochondria are crucial for cellular metabolism and signalling. Mitochondrial activity is modulated by mitochondrial fission and fusion, which are required to properly balance metabolic functions, transfer material between mitochondria, and remove defective mitochondria. Mitochondrial fission occurs at mitochondria-endoplasmic reticulum (ER) contact sites, and requires the formation of actin filaments that drive mitochondrial constriction and the recruitment of the fission protein DRP1.

Inhibition of RNA splicing triggers CHMP7 nuclear entry, impacting TDP-43 function and leading to the onset of ALS cellular phenotypes.

Amyotrophic lateral sclerosis (ALS) is linked to the reduction of certain nucleoporins in neurons. Increased nuclear localization of charged multivesicular body protein 7 (CHMP7), a protein involved in nuclear pore surveillance, has been identified as a key factor damaging nuclear pores and disrupting transport. Using CRISPR-based microRaft, followed by gRNA identification (CRaft-ID), we discovered 55 RNA-binding proteins (RBPs) that influence CHMP7 localization, including SmD1, a survival of motor neuron (SMN) complex component.

INF2-mediated actin polymerization at ER-organelle contacts regulates organelle size and movement.

Proper regulation of organelle dynamics and inter-organelle contacts is critical for cellular health and function. Both the endoplasmic reticulum (ER) and actin cytoskeleton are known to regulate organelle dynamics, but how, when, and where these two subcellular components are coordinated to control organelle dynamics remains unclear. Here, we show that ER-associated actin consistently marks mitochondrial, endosomal, and lysosomal fission sites.

INF2-mediated actin polymerization at ER-organelle contacts regulates organelle size and movement.

Proper regulation of organelle dynamics is critical for cellular function, but the mechanisms coordinating multiple organelles remain poorly understood. Here we show that actin polymerization mediated by the endoplasmic reticulum (ER)-anchored formin INF2 acts as a master regulator of organelle morphology and movement. Using high-resolution imaging, we demonstrate that INF2-polymerized actin filaments assemble at ER contact sites on mitochondria, endosomes, and lysosomes just prior to their fission.