Wolbachia are obligate intracellular bacteria that cause cytoplasmic incompatibility in mosquitoes. In an incompatible cross, eggs of uninfected females fail to hatch when fertilized by sperm from infected males. We used polyacrylamide gel electrophoresis and tandem mass spectrometry to identify Wolbachia proteins in infected mosquito gonads. These included surface proteins with masses of 25 and 18 kDa and the DNA binding protein, HU beta. Using reverse transcriptase polymerase chain reaction, we showed that the HU gene is transcribed in Wolbachia-infected Culex pipiens and Aedes albopictus mosquitoes. We sequenced HU genes from four Wolbachia strains and compared deduced protein sequences with additional homologs from the databases. Among the Rickettsiales, Wolbachia HU has distinct N- and C-terminal basic/acidic amino acid motifs as well as a pair of conserved, cysteine residues.
Bibliographical noteFunding Information:
This work was supported by NIH grant AI081322 and by the University of Minnesota Agricultural Experiment Station, St. Paul, MN . Mass spectrometry analysis was performed at the University of Minnesota Center for Mass Spectrometry and Proteomics (supporting agencies are listed at http://www.cbs.umn.edu/msp/about ). We thank Gerry Baldridge and Grace Li for helpful discussion and Cassandra Kurtz for help maintaining the mosquito colonies.
- Culex pipiens
- Cytoplasmic incompatibility
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