tba-1 encodes an alpha-tubulin widely expressed during C. elegans development. We showed previously that a dominant allele,
tba-1(
ju89), causes defects in locomotion and motor neuron development. To identify TBA-1-interacting proteins and better understand how microtubule dynamics and function are regulated in developing neurons, suppressors of
tba-1(
ju89) were isolated in a genetic screen based on reversion to wildtype movement. Multiple suppressors were mapped using snip-SNP analysis, and candidate suppressors were identified following whole genome sequencing. Two of the mutant genes identified by this approach were
klp-7 and
zer-1.
klp-7 encodes a member of the kinesin-13/MCAK family that function in microtubule depolymerization. In addition to early embryonic functions,
klp-7 is required for regrowth of neurons following laser axotomy (Ghosh-Roy et al., 2012). Experiments are in progress to test if KLP-7 expression and activity is altered in
tba-1(
ju89) mutants. Alternatively, decreased KLP-7 activity in the suppressor may compensate for another defect in microtubule dynamics due to altered TBA-1 function in the
ju89 mutants.
zer-1 encodes a conserved ubiquitin ligase substrate recognition subunit. Similar to the closely related protein, ZYG-11, ZER-1 interacts with C. elegans CUL-2 (Vasudevan, et al. 2007). The target substrates of ZER-1 are unknown, and it has not been implicated previously in neural development or function. ZER-1 may play a role in regulating tubulin stability directly or potentially modulate expression of critical regulators of tubulin, microtubules or microtubule-based transport in neurons.