Biology subjects

Reimer, J. M.

Publications and source records attributed to Reimer, J. M..

5 recordsLinked to original sources

bioRxiv2022

Structure of LRRK1 and mechanisms of autoinhibition and activation

Leucine Rich Repeat Kinase 1 and 2 (LRRK1 and LRRK2) are homologs in the ROCO family of proteins in humans. Despite their shared domain architecture and involvement in intracellular trafficking, their disease associations are strikingly different: LRRK2 is involved in familial Parkinsons Disease (PD) while LRRK1 is linked to bone diseases. Furthermore, PD-linked mutations in LRRK2 are typically autosomal dominant gain-of-function while those in LRRK1 are autosomal recessive loss-of-function. To understand these differences, we solved cryo-EM structures of LRRK1 in its monomeric and dimeric forms. Both differ from the corresponding LRRK2 structures. Unlike LRRK2, which is sterically autoinhibited as a monomer, LRRK1 is sterically autoinhibited in a dimer-dependent manner. LRRK1 has an additional level of autoinhibition that prevents activation of the kinase and is absent in LRRK2. Finally, we place the structural signatures of LRRK1 and LRRK2 in the context of the evolution of the LRRK family of proteins.

biochemistry↗

bioRxiv2022

Lis1 relieves cytoplasmic dynein-1 auto-inhibition by acting as a molecular wedge

Cytoplasmic dynein-1 transports many intracellular cargos towards microtubule minus ends. Dynein is autoinhibited and undergoes conformational changes to form an active complex, consisting of one or two dynein dimers, the dynactin complex and activating adaptor(s)1,2. The Lissencephaly 1 gene, LIS1, is genetically linked to the dynein pathway from fungi to mammals and is mutated in patients with the neurodevelopmental disease lissencephaly3-5. Lis1 is required for active dynein complexes to form6-10, but how it does so is unclear. Here, we present a structure of two dynein motor domains with two Lis1 dimers wedged in-between. The contact sites between dynein and Lis1 in this structure, termed "Chi", are required for Lis1s regulation of dynein in Saccharomyces cerevisiae in vivo and the formation of active human dynein-dynactin- activating adaptor complexes in vitro. We propose that this structure represents an intermediate in dyneins activation pathway, revealing how Lis1 relieves dyneins autoinhibited state.

cell biology↗

bioRxiv2022

Structures of human cytoplasmic dynein in complex with the lissencephaly 1 protein, LIS1

The lissencephaly 1 protein, LIS1, is mutated in type-1 lissencephaly and is a key regulator of cytoplasmic dynein-1. At a molecular level, current models propose that LIS1 activates dynein by relieving its autoinhibited form. We recently reported a 3.1[A] structure of yeast dynein bound to Pac1, the yeast homologue of LIS1, which revealed the details of their interactions (Gillies et al., 2022). Based on this structure, we made mutations that disrupted these interactions and showed that they were required for dyneins function in vivo in yeast. We also used our yeast dynein-Pac1 structure to design mutations in human dynein to probe the role of LIS1 in promoting the assembly of active dynein complexes. These mutations had relatively mild effects on dynein activation, suggesting that there may be differences in how dynein and Pac1/LIS1 interact between yeast and humans. Here, we report cryo-EM structures of human dynein-LIS1 complexes. Our new structures reveal the differences between the yeast and human systems and provide a blueprint to disrupt the human dynein-LIS1 interaction more accurately. Our new structures also allow us to map type-1 lissencephaly disease mutations, as well as mutations in dynein linked to malformations of cortical development/ intellectual disability, in the context of the human dynein-LIS1 complex.

cell biology↗

bioRxiv2021

Structural Basis for Cytoplasmic Dynein-1 Regulation by Lis1

The lissencephaly 1 gene, LIS1, is mutated in patients with the neurodevelopmental disease lissencephaly. The Lis1 protein is conserved from fungi to mammals and is a key regulator of cytoplasmic dynein-1, the major minus-end-directed microtubule motor in many eukaryotes. Lis1 is the only dynein regulator that binds directly to dyneins motor domain, and by doing so alters dyneins mechanochemistry. Lis1 is required for the formation of fully active dynein complexes, which also contain essential cofactors: dynactin and an activating adaptor. Here, we report the first high-resolution structure of the yeast dynein-Lis1 complex. Our 3.1[A] structure reveals, in molecular detail, the major contacts between dynein and Lis1 and between Lis1s {beta}-propellers. Structure-guided mutations in Lis1 and dynein show that these contacts are required for Lis1s ability to form fully active human dynein complexes and to regulate yeast dyneins mechanochemistry and in vivo function. We present a model for the conserved role of Lis1 in regulating dynein from yeast to humans.

cell biology↗

bioRxiv2020

Structural insights into assembly and function of the RSC chromatin remodeling complex

Chromatin remodelers regulate the position and composition of nucleosomes throughout the genome, producing different remodeling outcomes despite a shared underlying mechanism based on a conserved RecA DNA translocase. How this functional diversity is achieved remains unknown despite recent cryo-electron microscopy (cryo-EM) reconstructions of several remodelers, including the yeast RSC complex. To address this, we have focused on a RSC subcomplex comprising its ATPase (Sth1), the essential actin-related proteins (ARPs) Arp7 and Arp9, and the fungal-specific protein Rtt102. Combining cryo-EM and biochemistry of this subcomplex, which exhibits regulation of remodeling by the ARPs, we show that ARP binding induces a helical conformation in the HSA domain of Sth1, which bridges the ATPase domain with the bulk of the complex. Surprisingly, the ARP module is rotated by 120{degrees} in the subcomplex relative to full RSC about a pivot point previously identified as a regulatory hub in Sth1, suggesting that large conformational changes are part of Sth1 regulation and RSC assembly. We also show that an interaction between Sth1 and the nucleosome acidic patch, which appears to be conserved among SWI/SNF remodelers, enhances remodeling. Taken together, our structural data shed light on the assembly and function of the RSC complex.

molecular biology↗