Biology subjects

Wethekam, L. C.

Publications and source records attributed to Wethekam, L. C..

3 recordsLinked to original sources

bioRxiv2026

Discovery and in vivo characterization of novel TOG domain-containing proteins using C. elegans

The proper assembly, architecture, and maintenance of microtubule, actin and other cytoskeletal networks require regulation by various polymer binding proteins. Microtubules, rely on both the tubulin building blocks, but also many tubulin- and microtubule binding proteins. TOG domain-containing proteins comprise one family of tubulin-binding proteins that regulate microtubule dynamics. Here we identify two previously uncharacterized TOG domain-containing proteins (TOD-1 and TOD-2) in the nematode, C. elegans. These proteins are unique in that they are members of the XMAP215 family but contain reduced numbers of TOG domains and, in one case, a divergent TOG domain. TOD-1 and TOD-2 are expressed in and contribute to the normal function of sperm. The single TOG domain of TOD-1 and both TOG domains of TOD-2 are predicted to bind free tubulin dimers and not microtubule lattice. Deletion of either tod gene resulted in an increased laying of unfertilized oocytes. Inspection of mutant hermaphrodites revealed a premature onset of sperm migration failure. Together, these findings suggest that C. elegans requires regulation of tubulin dimers and/or microtubules for sperm localization and function. The amoeboid movement of C. elegans sperm has been considered microtubule-independent, our results open a new avenue of research into their unique motility.

cell biology↗

bioRxiv2023

Alpha-tubulin regulation by 5 introns in S. cerevisiae

Across eukaryotic genomes, multiple - and {beta}-tubulin genes require regulation to ensure sufficient production of tubulin heterodimers. Features within these gene families that regulate expression remain underexplored. Here we investigate the role of the 5 intron in regulating -tubulin expression in S. cerevisiae. We find that the intron in the -tubulin, TUB1, promotes -tubulin expression and cell fitness during microtubule stress. The role of the TUB1 intron depends on proximity to the TUB1 promoter and sequence features that are distinct from the intron in the alternative -tubulin isotype, TUB3. These results lead us to perform a screen to identify genes that act with the TUB1 intron. We identified several genes involved in chromatin remodeling, /{beta}-tubulin heterodimer assembly, and the spindle assembly checkpoint. We propose a model where the TUB1 intron promotes expression from the chromosomal locus, and that this may represent a conserved mechanism for tubulin regulation under conditions that require high levels of tubulin production. Article Summary and {beta}-tubulin proteins are encoded by families of genes that must be coordinately regulated to supply the {beta} heterodimers that form microtubules. This study by Wethekam and Moore identifies a role for the early intron in the budding yeast -tubulin, TUB1, in promoting gene function. A genetic screen reveals new tubulin regulators that act through the TUB1 intron. The results establish new layers of -tubulin regulation that may be conserved across eukaryotes.

genetics↗

bioRxiv2022

Asymmetric requirement for α-tubulin over β-tubulin

How cells regulate the supply of - and {beta}-tubulin monomers to meet the demand for {beta}- heterodimers while avoiding consequences of monomer imbalance is not understood. We investigate the role of gene copy number in tubulin regulation and how shifting the expression of - or {beta}-tubulin genes impacts tubulin proteostasis and microtubule function. We find that - tubulin gene copy number is important for maintaining an excess -tubulin protein compared to {beta}-tubulin protein and preventing accumulation of super-stoichiometric {beta}-tubulin. Super- stoichiometric {beta}-tubulin is toxic to cells, leading to loss of microtubules, formation of non- microtubule assemblies of tubulin, and disrupted cell proliferation. In contrast, decreased {beta}- tubulin or increased -tubulin has minor effects. We provide evidence that cells rapidly equilibrate the concentration of -tubulin protein during shifts in -tubulin isotype expression to maintain a ratio in excess of {beta}-tubulin. We propose an asymmetric relationship between - and {beta}-tubulins, where -tubulins are maintained in excess to supply {beta}-heterodimers and limit the accumulation of {beta}-tubulin monomers.

cell biology↗