Biology subjects

Phillips, B. P.

Publications and source records attributed to Phillips, B. P..

3 recordsLinked to original sources

bioRxiv2021

Structure of ATP synthase from ESKAPE pathogen Acinetobacter baumannii

Acinetobacter baumannii is a clinically relevant pathogen which causes multi-drug resistant, hospital-acquired infections and is a top priority target for antibiotic development. Cryo-EM structures of the A. baumannii F1Fo-ATP synthase in three conformational states reveal unique features, which represent attractive sites for the development of novel therapeutics. One sentence summaryStructure of Acinetobacter baumannii ATP synthase

biochemistry↗

bioRxiv2020

Structure and mechanism of TRAPPIII-mediated Rab1 activation

The GTPase Rab1 is a master regulator of both the early secretory pathway and autophagy. Rab1 activation is controlled by its GEF (guanine nucleotide exchange factor), the multi-subunit TRAPPIII complex. The Trs85 regulatory subunit is critical for robust activation of Rab1 but its mechanistic role within the complex has remained unclear. Here we report the cryo-EM structure of the intact yeast TRAPPIII complex bound to its substrate Rab1/Ypt1. The orientation of the Rab1/Ypt1 hypervariable domain when bound to the complex leads to a model for how TRAPPIII associates with and activates Rab1/Ypt1 at the membrane surface. We identify a conserved amphipathic -helix motif within Trs85 and demonstrate that this helix is required for stable membrane binding and Rab1/Ypt1 activation by TRAPPIII. Taken together, our results provide a comprehensive analysis of the structure and function of the yeast TRAPPIII complex and reveal that the key function of Trs85 is to serve as a membrane anchor, via its amphipathic helix, for the entire TRAPPIII complex.

cell biology↗

bioRxiv2020

The architecture of EMC reveals a path for membrane protein insertion

Approximately 25% of eukaryotic genes code for integral membrane proteins that are assembled at the endoplasmic reticulum. An abundant and widely conserved multi-protein complex termed EMC has been implicated in membrane protein biogenesis, but its mechanism of action is poorly understood. Here, we define the composition and architecture of human EMC using biochemical assays, crystallography of individual subunits, site-specific photocrosslinking, and cryo-EM reconstruction. Our results show that EMCs cytosolic domain contains a large, moderately hydrophobic vestibule that binds a substrates transmembrane domain (TMD). The cytosolic vestibule leads into a lumenally-sealed, lipid-exposed intramembrane groove large enough to accommodate a single substrate TMD. A gap between the cytosolic vestibule and intramembrane groove provides a path for substrate egress from EMC. These findings suggest how EMC facilitates energy-independent membrane insertion of TMDs, explain why only short lumenal domains are translocated by EMC, and constrain models of EMCs proposed chaperone function.

biochemistry↗