Spatiotemporal dissection of the Golgi apparatus and the ER-Golgi intermediate compartment in budding yeast
Takuro Tojima, Yasuyuki Suda, Natsuko Jin, Kazuo Kurokawa, Akihiko Nakano
Abstract
Cargo traffic through the Golgi apparatus is mediated by cisternal maturation, but it remains largely unclear how the cis -cisternae, the earliest Golgi sub-compartment, is generated and how the Golgi matures into the trans -Golgi network (TGN). Here, we use high-speed and high-resolution confocal microscopy to analyze the spatiotemporal dynamics of a diverse set of proteins that reside in and around the Golgi in budding yeast. We find many mobile punctate structures that harbor yeast counterparts of mammalian endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC) proteins, which we term ‘yeast ERGIC’. It occasionally exhibits approach and contact behavior toward the ER exit sites and gradually matures into the cis -Golgi. Upon treatment with the Golgi-disrupting agent brefeldin A, the ERGIC proteins form larger aggregates corresponding to the Golgi entry core compartment in plants, while cis - and medial-Golgi proteins are absorbed into the ER. We further analyze the dynamics of several late Golgi proteins to better understand the Golgi-TGN transition. Together with our previous studies, we demonstrate a detailed spatiotemporal profile of the entire cisternal maturation process from the ERGIC to the Golgi and further to the TGN.