A convenient tool for bivariate data analysis and bar graph plotting with R.

The Java software jBar consists of a graphical user interface that allows the user to customize and assemble an included script for R. The scripted R pipeline calculates means and standard errors/deviations for replicates of numerical bivariate data and generates presentations in the form of bar graphs. A two-sided Student's t test is carried out against a user-selected reference and p-values are calculated. The user can enter the data conveniently through the built-in spreadsheet and configure the R pipeline in the graphical user interface. The configured R script is written into a file and then executed. Bar graphs can be generated as static PNG, PDF, and SVG files or as interactive HTML widgets. © 2019 International Union of Biochemistry and Molecular Biology, 47(2): 207-210, 2019.

The regulatory subunit phr2AB of Dictyostelium discoideum phosphatase PP2A interacts with the centrosomal protein CEP161, a CDK5RAP2 ortholog.

phr2AB is the regulatory subunit of the Dictyostelium discoideum phosphatase PP2A and is the ortholog of the human B55 regulatory subunit of PP2A. phr2AB was isolated as a binding partner of the centrosomal protein CEP161, an ortholog of mammalian CDK5RAP2. CEP161 is presumably a phosphoprotein and a component of the Hippo pathway. The interaction site was located in the N-terminal half of CEP161 which encompasses the γTURC binding domain in CEP161. This binding domain is responsible for binding of the γ-tubulin ring complex which allows microtubule nucleation at the centrosome. GFP-tagged phr2AB is diffusely distributed throughout the cell and enriched at the centrosome. Ectopic expression of phr2AB as GFP fusion protein led to multinucleation, aberrant nucleus centrosome ratios and an altered sensitivity to okadaic acid. Some of these features were also affected in cells over-expressing domains of CEP161 and in cells from patients suffering from primary microcephaly, which carried a mutated CDK5RAP2 gene.

A tripeptidyl peptidase 1 is a binding partner of the Golgi pH regulator (GPHR) in Dictyostelium.

Mutations in tripeptidyl peptidase 1 (TPP1) have been associated with late infantile neuronal ceroid lipofuscinosis (NCL), a neurodegenerative disorder. TPP1 is a lysosomal serine protease, which removes tripeptides from the N-terminus of proteins and is composed of an N-terminal prodomain and a catalytic domain. It is conserved in mammals, amphibians, fish and the amoeba Dictyostelium discoideum. D. discoideum harbors at least six genes encoding TPP1, tpp1A to tpp1F We identified TPP1F as binding partner of Dictyostelium GPHR (Golgi pH regulator), which is an evolutionarily highly conserved intracellular transmembrane protein. A region encompassing the DUF3735 (GPHR_N) domain of GPHR was responsible for the interaction. In TPP1F, the binding site is located in the prodomain of the protein. The tpp1F gene is transcribed throughout development and translated into a polypeptide of ∼65 kDa. TPP1 activity was demonstrated for TPP1F-GFP immunoprecipitated from D. discoideum cells. Its activity could be inhibited by addition of the recombinant DUF3735 domain of GPHR. Knockout tpp1F mutants did not display any particular phenotype, and TPP1 activity was not abrogated, presumably because tpp1B compensates as it has the highest expression level of all the TPP1 genes during growth. The GPHR interaction was not restricted to TPP1F but occurred also with TPP1B. As previous reports show that the majority of the TPP1 mutations in NCL resulted in reduction or loss of enzyme activity, we suggest that Dicyostelium could be used as a model system in which to test new reagents that could affect the activity of the protein and ameliorate the disease.