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Convergent Aedes and Drosophila CidB interactomes suggest cytoplasmic incompatibility targets are conserved
Seun O Oladipupo1, Jazmine D Carroll2, John F Beckmann2
1Department of Entomology & Plant Pathology, Auburn University, Auburn, AL, 36849, USA; Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, 06520, USA.
Abstract:
Wolbachia-mediated cytoplasmic incompatibility (CI) is a conditional embryonic lethality induced when Wolbachia-modified sperm fertilizes an uninfected egg. The Wolbachia proteins, CidA and CidB control CI. CidA is a rescue factor that reverses lethality. CidA binds to CidB. CidB contains a deubiquitinating enzyme and induces CI. Precisely how CidB induces CI and what it targets are unknown. Likewise, how CidA prevents sterilization by CidB is not clear. To identify CidB substrates in mosquitos we conducted pull-down assays using recombinant CidA and CidB mixed with Aedes aegypti lysates to identify the protein interactomes of CidB and the CidB/CidA protein complex. Our data allow us to cross compare CidB interactomes across taxa for Aedes and Drosophila. Our data replicate several convergent interactions, suggesting that CI targets conserved substrates across insects. Our data support a hypothesis that CidA rescues CI by tethering CidB away from its substrates. Specifically, we identify ten convergent candidate substrates including P32 (protamine-histone exchange factor), karyopherin alpha, ubiquitin-conjugating enzyme, and bicoid stabilizing factor. Future analysis on how these candidates contribute to CI will clarify mechanisms.
Insights
Wolbachia bacteria cause cytoplasmic incompatibility (CI) by producing proteins CidA and CidB. This study identifies key protein targets of CidB, revealing conserved mechanisms of CI across insects.
Area of Science:
- Molecular biology
- Insect reproductive biology
- Microbial symbiosis
Background:
- Wolbachia bacteria induce cytoplasmic incompatibility (CI), a reproductive barrier causing embryonic lethality in insects.
- The Wolbachia proteins CidA and CidB are known to regulate CI, with CidB inducing the effect and CidA acting as a rescue factor.
- The precise molecular targets and mechanisms of CidB-induced CI and CidA-mediated rescue remain largely unelucidated.
Purpose of the Study:
- To identify protein substrates targeted by the Wolbachia protein CidB in mosquitoes.
- To investigate the protein interactome of the CidB/CidA complex to understand the mechanism of CI rescue.
- To compare CidB interactomes across insect taxa to identify conserved CI targets.
Main Methods:
- Utilized pull-down assays with recombinant CidA and CidB proteins.
- Analyzed protein interactions using Aedes aegypti lysates to identify CidB and CidB/CidA complex interactomes.
- Cross-taxa comparison of CidB interactomes between Aedes and Drosophila.
Main Results:
- Identified ten convergent candidate protein substrates of CidB conserved across insect taxa.
- Candidate substrates include P32 (protamine-histone exchange factor), karyopherin alpha, ubiquitin-conjugating enzyme, and bicoid stabilizing factor.
- Data support the hypothesis that CidA rescues CI by sequestering CidB away from its substrates.
Conclusions:
- CI targets conserved protein substrates across diverse insect species.
- CidA likely rescues CI by preventing CidB from interacting with its essential cellular targets.
- Further investigation of identified candidate substrates will elucidate the molecular mechanisms underlying CI.
