dictyNews

Electronic Edition

Volume 43, number 11

May 19, 2017



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Abstracts

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A Tripeptidyl peptidase 1 is a binding partner of GPHR (Golgi pH regulator) 

in Dictyostelium



Maria Stumpf1, Rolf Müller1, Berthold Gaßen1, Regina Wehrstedt1, Petra Fey2, 

Malte A. Karow1, Ludwig Eichinger1, Gernot Glöckner1, Angelika A. Noegel1



1Institute of Biochemistry I, Medical Faculty, University Hospital Cologne, 

University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany;

2dictyBase, Northwestern University, Biomedical Informatics Center and 

Center for Genetic Medicine, Chicago, Illinois, USA





Disease Models & Mechanisms, in press



Mutations in tripeptidyl peptidase 1 (TPP1) have been associated with late 

infantile neuronal ceroid lipofuscinosis (NCL2), a neurodegenerative disorder. 

TPP1 is a lysosomal serine protease, which removes tripeptides from the 

amino 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 tripeptidyl peptidase 1, tpp1A to tpp1F. We identified TPP1F as 

binding partner of Dictyostelium GPHR (Golgi pH regulator), which is an 

evolutionary highly conserved intracellular transmembrane protein. For the 

interaction, a region encompassing the DUF3735 (GPHR_N) domain of GPHR 

was responsible. In TPP1F the binding site was located in the prodomain. The 

Tpp1F gene is transcribed throughout development and translated into a 

polypeptide of approximately 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 a particular phenotype and TPP1 activity was not 

abrogated, which is presumably due to expression of Tpp1B showing the highest 

expression levels of all Tpp1 genes during growth. The GPHR interaction was 

not restricted to TPP1F but occurred also with TPP1B. Based on previous reports 

showing that the majority of the TPP1 mutations in NCL2 resulted in reduction or

 loss of enzyme activity, our findings may help to create new reagents with which 

 one can affect the activity of the protein and ameliorate the disease.





submitted by: Ludwig Eichinger [[log in to unmask]]

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Multiple Dictyostelid Species Destroy Biofilms of Klebsiella oxytoca and Other 

Gram Negative Species



Dean Sanders1, Katarzyna D. Borys2, Fikrullah Kisa3, Sheryl A. Rakowski4, 

Marcela Lozano, Marcin Filutowicz5





https://doi.org/10.1016/j.protis.2017.04.001



Dictyostelids are free-living phagocytes that feed on bacteria in diverse habitats. 

When bacterial prey is in short supply or depleted, they undergo multicellular 

development culminating in the formation of dormant spores. In this work, we 

tested isolates representing four dictyostelid species from two genera (Dictyostelium 

and Polysphondylium) for the potential to feed on biofilms preformed on glass and 

polycarbonate surfaces. The abilities of dictyostelids were monitored for three 

hallmarks of activity: 1) spore germination on biofilms, 2) predation on biofilm 

enmeshed bacteria by phagocytic cells and 3) characteristic stages of multicellular 

development (streaming and fructification). We found that all dictyostelid isolates 

tested could feed on biofilm enmeshed bacteria produced by human and plant 

pathogens: Klebsiella oxytoca, Pseudomonas aeruginosa, Pseudomonas syringae, 

Erwinia amylovora 1189 (biofilm former) and E. amylovora 1189 Δams (biofilm 

deficient mutant). However, when dictyostelids were fed planktonic E. amylovora 

Δams the bacterial cells exhibited an increased susceptibility to predation by one 

of the two dictyostelid strains they were tested against. Taken together, the 

qualitative and quantitative data presented here suggest that dictyostelids have 

preferences in bacterial prey which affects their efficiency of feeding on bacterial 

biofilms.





submitted by: Marcin Filutowicz [[log in to unmask]]

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[End dictyNews, volume 43, number 11]