Functional analysis of Wolbachia Cid effectors unravels cooperative interactions to target host chromatin during replication

PLoS Pathog. 2023 Mar 16;19(3):e1011211. doi: 10.1371/journal.ppat.1011211. eCollection 2023 Mar.

Abstract

Wolbachia are common bacteria among terrestrial arthropods. These endosymbionts transmitted through the female germline manipulate their host reproduction through several mechanisms whose most prevalent form called Cytoplasmic Incompatibility -CI- is a conditional sterility syndrome eventually favoring the infected progeny. Upon fertilization, the sperm derived from an infected male is only compatible with an egg harboring a compatible Wolbachia strain, this sperm leading otherwise to embryonic death. The Wolbachia Cif factors CidA and CidB responsible for CI and its neutralization function as a Toxin-Antitoxin system in the mosquito host Culex pipiens. However, the mechanism of CidB toxicity and its neutralization by the CidA antitoxin remain unexplored. Using transfected insect cell lines to perform a structure-function analysis of these effectors, we show that both CidA and CidB are chromatin interactors and CidA anchors CidB to the chromatin in a cell-cycle dependent-manner. In absence of CidA, the CidB toxin localizes to its own chromatin microenvironment and acts by preventing S-phase completion, independently of its deubiquitylase -DUB- domain. Experiments with transgenic Drosophila show that CidB DUB domain is required together with CidA during spermatogenesis to stabilize the CidA-CidB complex. Our study defines CidB functional regions and paves the way to elucidate the mechanism of its toxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Centromere Protein A / metabolism
  • Chromatin / metabolism
  • Cytoplasm / metabolism
  • Drosophila / metabolism
  • Drosophila Proteins* / metabolism
  • Male
  • Semen / metabolism
  • Wolbachia* / physiology

Substances

  • Chromatin
  • Cid protein, Drosophila
  • Centromere Protein A
  • Drosophila Proteins

Grants and funding

This work was supported by several fundings from the French Agence Nationale de la Recherche (https://anr.fr/en/) «Investments for the future»: ANR-16-IDEX-0006 -FL and MW-, ANR-10-INBS-04 -BL, BH-; and a grant from the Fondation Schlumberger pour l’Education et la Recherche (http://www.cerclefser.org/en/) FSER202002011118 to FL. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.