Sufu (Suppressor of fused) is a negative regulator of the Hedgehog signal-transduction pathway, interacting directly with the Gli family of transcription factors. However, its function remains poorly understood. In the present study, we determined the expression, tissue distribution and biochemical properties of mSufu (mouse Sufu) protein. We identified several mSufu variants of which some were phosphorylated. A yeast two-hybrid screen with mSufu as bait allowed us to identify several nuclear proteins as potential partners of mSufu. Most of these partners, such as SAP18 (Sin3-associated polypeptide 18), pCIP (p300/CBP-cointegrator protein) and PIAS1 (protein inhibitor of activated signal transduction and activators of transcription 1), are involved in either repression or activation of transcription and two of them, Galectin3 and hnRNPA1 (heterogeneous nuclear ribonucleoprotein A1), have a nuclear function in pre-mRNA splicing. We confirmed the mSufu-SAP18 and mSufu-Galectin3 interactions by independent biochemical assays. Using a cell transfection assay, we also demonstrated that mSufu protein (484 amino acids) is predominantly cytoplasmic but becomes mostly nuclear when a putative nuclear export signal is mutated or after treatment of the cells with leptomycin B. Moreover, mSufu is translocated to the nucleus when co-expressed with SAP18, which is normally found in this compartment. In contrast, Galectin3 is translocated to the cytoplasm when it is co-expressed with mSufu. Our findings indicate that mSufu is a shuttle protein that appears to be extremely versatile in its ability to bind different proteins in both the cytoplasm and nucleus.

We determined the 16S rRNA gene sequences of three crustacean "Rickettsiella armadillidii" strains. Rickettsiella bacteria overall appear to form a monophyletic group that diverged from Coxiella bacteria ϳ350 million years ago. Therefore, the genus Rickettsiella as a whole (not just Rickettsiella grylli) should be classified among the Gammaproteobacteria instead of the Alphaproteobacteria.Members of the genus Rickettsiella are intracellular bacterial pathogens of arthropods (13). They are found in a wide range of hosts including insects, crustaceans, and arachnids, and they exhibit a worldwide geographic distribution (11-13). In naturally infected hosts, the Rickettsiella-mediated disease affects both larvae and adults and develops very slowly (13). In its crustacean hosts, "Rickettsiella armadillidii" induces death, preceded by loss of weight and a white coloration of intersegmentary membranes, and the host general cavity is filled with an iridescent white liquid (12). Rickettsiella bacteria can potentially be very contagious, since they are capable of surviving in soil for years before contaminating new hosts (13).On the basis of ultrastructural observations, Rickettsiella bacteria have been classified among the Alphaproteobacteria, within the order Rickettsiales, the family Rickettsiaceae, and the tribe Wolbachieae (13). However, the 16S rRNA gene sequence of R. grylli isolated from the cricket suggested that this strain is a Gammaproteobacterium related to the genus Coxiella (10). Therefore, if the genus Rickettsiella is monophyletic (i.e., all Rickettsiella species share an exclusive, common ancestor), then the taxonomic position of the genus Rickettsiella as a whole needs to be reassessed. Otherwise, if only R. grylli has been misclassified among the Gammaproteobacteria, the genus Rickettsiella is polyphyletic (i.e., different Rickettsiella species have different evolutionary origins). To obtain new insight into the evolution of Rickettsiella bacteria, we characterized Rickettsiella molecular genetic variation by analyzing the 16S rRNA gene sequences of three strains of the crustacean pathogen "R. armadillidii" (12) along with a data set of Rickettsiella-like 16S rRNA gene sequences encompassing their entire known host spectrum, gathered through database searches.Wild-caught individuals belonging to the three isopod crustacean species Armadillidium vulgare (from Camarade, Ariège, France), Helleria brevicornis (from Pietracorbara, Corsica, France), and Philoscia muscorum (from Santiago de Compostela, Galicia, Spain) were studied. The animals displayed the characteristic external symptoms of an infection by "R. armadillidii," as described above (12). The diagnosis was further confirmed during the dissection of the samples and by electron microscopy. We determined the nucleotide sequences of the 16S rRNA genes of the three "R. armadillidii" strains from the aforementioned isopods by using standard methods of DNA extraction, PCR amplification, and sequencing (2, 9). We performed PCR amplification with primers ...