A VPS15-like kinase regulates apicoplast biogenesis and autophagy by promoting PI3P generation in Toxoplasma gondii

Keeping your endosymbiont under control: the enigmatic plastid membrane ATG8ylation in Apicomplexa parasites

ATG8ylation of membranes has been increasingly reported over the last few years, in various configurations and across different eukaryotic models. While the unconventional conjugation of ATG8 to the outermost membrane of the plastid in apicomplexan parasites was first observed over a decade ago, it is often overlooked in literature reviews focusing on the ATG8ylation of non-autophagosomal membranes. Here, I provide a brief overview of the current knowledge on plastid ATG8ylation in these parasites and discuss a possible parallel between the evolutionary origin of this plastid and other ATG8ylation processes, such as LC3-associated phagocytosis.

The apicoplast biogenesis and metabolism: current progress and questions

Many apicomplexan parasites have a chloroplast-derived apicoplast containing several metabolic pathways. Recent studies have greatly expanded our understanding of apicoplast biogenesis and metabolism while also raising new questions. Here, we review recent progress on the biological roles of individual metabolic pathways, focusing on two medically important parasites, Plasmodium spp. and Toxoplasma gondii. We highlight the similarities and differences in how similar apicoplast metabolic pathways are utilized to adapt to different parasitic lifestyles. The execution of apicoplast metabolic functions requires extensive interactions with other subcellular compartments, but the underlying mechanisms remain largely unknown. Apicoplast metabolic functions have historically been considered attractive drug targets, and a comprehensive understanding of their metabolic capacities and interactions with other organelles is essential to fully realize their potential.

Trichinella spiralis inhibits myoblast differentiation by targeting SQSTM1/p62 with a secreted E3 ubiquitin ligase

Trichinella spiralis infection is associated with the formation of cysts within host skeletal muscle cells, thereby enabling immune evasion and subsequent growth and development; however, the pathogenic factors involved in this process and their mechanisms remain elusive. Here, we found that Ts-RNF secreted by T. spiralis is required for its growth and development in host cells. Further study revealed that Ts-RNF functions as an E3 ubiquitin ligase that targets the UBA domain of SQSTM1/p62 by forming K63-type ubiquitin chains. This modification interferes with autophagic flux, leading to impaired mitochondrial clearance and abnormal myotube differentiation and fusion. Our results established that T. spiralis increases its escape by interfering with host autophagy via the secretion of an E3 ubiquitin ligase.