Genetic Studies on Dynamin Function inDrosophila

Abstract

The shibire(ts2) mutation of Drosophila melanogaster causes a temperature sensitive inhibition of endocytosis; this in turn leads to synaptic-vesicle depletion and consequent paralysis. Heat-pulses delivered during development of shibire(ts2) individuals affect the morphology of a number of adult structures. A simple screening protocol has been used to isolate several mutations that partially suppress the temperature-sensitive paralytic phenotype of shibire(ts2) mutant animals. All of these mutations very tightly linked to shibire and are likely to be second site intragenic mutations that restore partial activity to the shibire(ts2) product. The mutations suppress both behavioral, and easily-scored developmental phenotypes of shibire(ts2) characterized in this paper. Our results suggest that defects in endocytosis, and not in microtubule interactions, are responsible for all of the phenotypes of shibire(ts2) mutant Drosophila examined in this study.

Crystal structure of the GTPase domain of rat dynamin 1

“…However, mutation Arg59Cys rescues the GTP binding defect displayed by shi ts2 mutants at 30°C. This mutation was identified in a genetic screen for suppressors of shi ts2 (sushi) mutations (33). To test whether Arg-59 plays a role in GTP binding or hydrolysis, we introduced mutations Arg59Ala or Arg59Lys into full-length dynamin 1 and purified the mutant proteins for kinetic analysis.…”

Remembering K. S. Krishnan (1946–2014)

“…Indeed, we recall with fondness his search for synonyms in diff erent languages to better name new mutants with. The screen for suppressors gave multiple interesting alleles of shibire itself, which later provided fundamental insights into functional interactions between the subdomains of the Dynamin protein (Ramaswami et al, 1993;Grant et al, 1998;Narayanan et al, 2005). The screen for enhancers yielded several diff erent alleles of shibire in addition to two enhancers, which aff ected nucleotide (ATP and GTP) levels at the synapse and in turn specifi cally aff ected synaptic vesicle recycling (Krishnan et al, 2001;Rikhy et al, 2003).…”

Endocytosis in Notch Signaling Activation

“…a temperature-sensitive mutant of the endocytic fission protein dynamin in flies [145]), results in a developmental phenotype with an excess of neural cells when raised to restrictive temperature, i.e. with defects which closely phenocopy the Notch mutant [146,147]. This phenotype is in sharp contrast to other signaling pathways, which are not severely disrupted in the shibire mutant (e.g.…”