Biology subjects

Goode, B. L.

Publications and source records attributed to Goode, B. L..

5 recordsLinked to original sources

bioRxiv2026

Dynamin proline-rich domain isoform abundance, not identity, determines synaptic vesicle recycling efficiency in Drosophila

During neurotransmission, synaptic vesicle exocytosis adds membrane and proteins to the cell surface. To sustain further release, this material must be retrieved, via several distinct endocytic modes matched to the level of exocytosis. The GTPase dynamin plays a central role in endocytosis, but it has remained unclear which endocytic modes it supports. In mammals, distinct dynamin gene products with different proline-rich domains (PRDs) are proposed to mediate particular modes of endocytosis; however, the function of each PRD isoform has not been tested in an organism. Drosophila dynamin is encoded by one gene (shibire) that produces long and short PRD isoforms (Shi-L and Shi-S), which differ by a 48 amino acid C-terminal extension. Using isoform-specific knockin and knockdown tools, we found that loss of the more abundant Shi-S isoform disrupted bulk endocytosis and vesicle reformation under high exocytic demand, reduced evoked transmission at moderate levels of activity, and enhanced spontaneous release at rest. These functions did not depend on the PRD extension, as either isoform could rescue these phenotypes when re-expressed. Our results indicate that dynamin contributes to vesicle recycling across multiple endocytic retrieval modes and that PRD specialization is not required for these functions.

cell biology↗

bioRxiv2023

Universal length fluctuations of actin structures found in cells

Actin is a key cytoskeletal protein that forms filaments that bundle into linear structures in vivo, which are involved in motility, signaling, and cell division. Despite the rapid turnover of individual actin monomers, these structures are often maintained at a specific length, which is important for their function. Length control is commonly attributed to length-dependent assembly or disassembly of the structure, whereby a stable length is achieved when the two opposing processes are balanced. Here we show that regardless of the nature of the length-dependent feedback, such "balance point" models predict a Gaussian distribution of lengths with a variance that is proportional to the steady state length. Contrary to this prediction, a reexamination of experimental measurements on the lengths of stereocilia, microvilli, actin cables, and filopodia reveals that the variance scales with the square of the steady state length. We propose a model in which the individual filaments in bundles undergo independent assembly dynamics, and the length of the bundle is set by the length of the longest filament. This model predicts a non-Gaussian distribution of bundle lengths with a variance that scales with the square of the steady state length. Our theory underscores the importance of crosslinking filaments into networks for size control of cytoskeleton structures.

cell biology↗

bioRxiv2023

Bitesize bundles F-actin and influences actin remodeling in syncytial Drosophila embryo development

Actin networks undergo rearrangements that influence cell and tissue shape. Actin network assembly and organization is regulated in space and time by a host of actin binding proteins. The Drosophila Synaptotagmin-like protein, Bitesize (Btsz), is known to organize actin at epithelial cell apical junctions in a manner that depends on its interaction with the actin-binding protein, Moesin. Using RNAi, we showed that Btsz functions at earlier, syncytial stages of Drosophila embryo development. Btsz is required to stabilize pseudo-cleavage furrows that prevent metaphase spindle collisions and nuclear fallout prior to cellularization. While previous studies have focused on Btsz function through Moesin, we find that phosphorylated Moesin localized to the nuclear envelope and was not enriched at pseudo-cleavage furrows, suggesting a Moesin-independent function for Btsz in syncytial embryos. Consistent with this, mutants that affected all Moesin binding domain isoforms did not recapitulate pan-isoform Btsz depletion and we find that the C-terminal half of Btsz cooperatively binds to and bundles F-actin. We propose that Synaptotagmin-like proteins directly regulate actin organization during syncytial Drosophila development.

cell biology↗

bioRxiv2021

Single-molecule imaging of IQGAP1 regulating actin filament dynamics in real time

IQGAP is a conserved family of actin-binding proteins with essential roles in cell motility, cytokinesis, and cell adhesion, yet it has remained poorly understood how IQGAP proteins directly regulate actin filament dynamics. To close this gap, we used single-molecule and single-filament TIRF microscopy to directly visualize IQGAP regulating actin dynamics in real time. To our knowledge, this is the first study to do so. Our results show that full-length human IQGAP1 forms dimers that stably bind to filament sides and transiently cap barbed ends. These interactions organize actin filaments into thin bundles, suppress barbed end growth, and inhibit filament disassembly. Surprisingly, each activity depends on distinct combinations of IQGAP1 domains and/or dimerization, suggesting that different mechanisms underlie each functional effect on actin. These observations have important implications for how IQGAP functions as a direct actin regulator in vivo, and how it is deployed and regulated in different biological settings.

biochemistry↗

bioRxiv2021

Scaling of subcellular structures with cell length through decelerated growth

How cells tune the size of their subcellular parts to scale with cell size is a fundamental question in cell biology. Until now, most studies on the size control of organelles and other subcellular structures have focused on scaling relationships with cell volume, which can be explained by limiting pool mechanisms. Here, we uncover a distinct scaling relationship with cell length rather than volume, revealed by mathematical modeling and quantitative imaging of yeast actin cables. The extension rate of cables decelerates as they approach the rear of the cell, until cable length matches cell length. Further, the deceleration rate scales with cell length. These observations reveal a new mode of scaling that senses the linear dimensions of a cell. One Sentence SummaryAs actin cables in yeast cells grow longer, their extension rate decelerates, enabling the cable length to match cell length.

cell biology↗