In Saccharomyces cerevisiae, aminopeptidase I (Ape1p) and ␣-mannosidase (Ams1p) are known cargoes of selective autophagy. Atg19p has been identified as an Ape1p receptor and targets Ape1p to the preautophagosomal structure (PAS). Under nutrient-rich conditions, transport of Ams1p to the vacuole largely depends on Atg19p. Here, we show that Atg34p (Yol083wp), a homolog of Atg19p, is a receptor for Ams1p transport during autophagy. Atg34p interacted with Ams1p, Atg11p, and Atg8p using distinct domains. Homo-oligomerized Ams1p bound to the Ams1-binding domain of Atg34p; this binding was important for the formation of a higher order complex named the Ams1 complex. In the absence of the interaction of Atg34p with Atg8p, the Ams1 complex was targeted to the preautophagosomal structure but failed to transit to the vacuole, indicating that the interaction of Atg34p with Atg8p is crucial for the Ams1 complex to be enclosed by autophagosomes. Atg34p and Atg19p have similar domain structures and are important for Ams1p transport during autophagy.Macroautophagy (hereafter simply called autophagy) has been described as a non-selective degradation system of cytoplasmic constituents. Recently, selective degradation of proteins and organelles by autophagy has been shown to be important for the homeostasis of eukaryotic cells by eliminating unnecessary or harmful proteins and organelles such as mitochondria and peroxisomes.Thirty-three autophagy-related (ATG) 2 genes have been identified as requisites for several types of autophagy in yeast. Among them, 18 genes are essential for autophagosome formation under starvation conditions (1). Atg proteins encoded by these genes are organized into the preautophagosomal structure (PAS), which plays a central role in autophagosome formation near the vacuole (2). During autophagy, cytoplasmic constituents are sequestered by the double membrane of an autophagosome. The outer membrane of the autophagosome fuses with the vacuole membrane. The inner structure, an autophagic body, is released into the vacuolar lumen and degraded by the action of vacuolar hydrolases.Previous analysis showed that the resident vacuolar hydrolases, ␣-mannosidase (Ams1p) and aminopeptidase I (Ape1p), are transported to the vacuole via selective autophagy (3, 4). Ams1p oligomerizes after synthesis and associates with a precursor Ape1p (prApe1p) by the action of Atg19p (4, 5). Ams1p, prApe1p, and Atg19p assemble into a large complex called the cytoplasm-to-vacuole targeting (Cvt) complex, which was identified as an electron-dense structure localized close to the vacuole by electron microscopy (3). Atg19p mediates the association of the Cvt complex with the PAS by interacting with Atg8p and Atg11p (5, 6). The Cvt complex is selectively enclosed in a Cvt vesicle (about 150 nm in diameter) under nutrient-rich conditions and in an autophagosome (about 500 nm in diameter) under starvation conditions. After transport to the vacuole, prApe1p is processed into mature Ape1p (mApe1p).Under nutrient-rich conditions, Atg19p is es...

Macroautophagy (autophagy) is a bulk degradation system for cytoplasmic components and is ubiquitously found in eukaryotic cells. Autophagy is induced under starvation conditions and plays a cytoprotective role by degrading unwanted cytoplasmic materials. The Ty1 transposon, a member of the Ty1/copia superfamily, is the most abundant retrotransposon in the yeast Saccharomyces cerevisiae and acts to introduce mutations in the host genome via Ty1 virus-like particles (VLPs) localized in the cytoplasm. Here we show that selective autophagy downregulates Ty1 transposition by eliminating Ty1 VLPs from the cytoplasm under nutrient-limited conditions. Ty1 VLPs are targeted to autophagosomes by an interaction with Atg19. We propose that selective autophagy safeguards genome integrity against excessive insertional mutagenesis caused during nutrient starvation by transposable elements in eukaryotic cells.

A viable synthetic route to the furaquinocin-class antibiotics is described. The key steps include (1) Co-complex mediated stereospecific 1,2-shift of an alkynyl group (9 → 6) to establish the C(2)−C(3) stereochemical relationship, (2) efficient construction of furanonaphthalene 20 from the sodium carboxylate derived from ester 19, and (3) stereoselective methylene transfer reaction to aldehyde 21 to establish the three contiguous stereogenic centers, C(2), C(3), and C(10). The stereodefined epoxide 23, thus obtained, served as a versatile intermediate in divergent syntheses of four congeners of this class of natural products, furaquinocins A (1a), B (1b), D (1d), and H (1h), by changing the vinylic nucleophiles.

The time it takes seeds to pass through the gut of vertebrates is an important aspect of endozoochorous seed dispersal because it influences seed dispersal distance. The physical characteristics of seeds (e.g. dry seed weight, volume and specific gravity) vary among plant species, which might cause a difference in seed movement through the gastrointestinal system. We conducted feeding experiments with captive female Japanese macaques Macaca fuscata (n = 5) using eight different types of seeds to evaluate the effects of the physical characteristics of seeds on their passage time. The median seed recovery percentage for the real seeds was 35.5% (range, 24-78%). Among three passage time variables examined, the mean retention time (MRT) (37-54 h) and time of last appearance of a seed (TLA) (53-109 h) differed significantly among seed types, and the former differed significantly among individuals. Transit time (TT) (22-35 h) did not. The generalized linear models (GLM) selected dry seed weight as the most important factor affecting MRT, and specific gravity of seeds as the most important factor affecting TLA. This implies that (1) heavier seeds and (or) seeds with greater specific gravity remain in the gut longer and are likely to be dispersed farther from the parent plant; (2) the lighter seeds and (or) seeds with lower specific gravity are dispersed nearer the parent. Our study demonstrated the importance of considering the effects of the physical characteristics of seeds on the manner in which primates disperse plant species, although we should consider the effect of the individual variation in the passage time, too.