dictyNews

Electronic Edition

Volume 46, number 2

January 10, 2020



Please submit abstracts of your papers as soon as they have been

accepted for publication by sending them to [log in to unmask]

or by using the form at

http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit.



Back issues of dictyNews, the Dicty Reference database and other

useful information is available at dictyBase - http://dictybase.org.



Follow dictyBase on twitter:

http://twitter.com/dictybase





=========

Abstracts

=========





Mitochondrial localization of Dictyostelium discoideum dUTPase mediated 

by its N-terminus



C.P. Chia, N. Inoguchi, K.C. Varon, B.M. Bartholomai and H. Moriyama





BMC Research Notes 2020 13:16; Published on: 7 January 2020



The nuclear and mitochondrial genomes of Dictyostelium discoideum, a 

unicellular eukaryote, have relatively high A+T-contents of 77.5% and 72.65%, 

respectively. To begin to investigate how the pyrimidine biosynthetic pathway 

fulfills the demand for dTTP, we determined the catalytic properties and 

structure of the key enzyme deoxyuridine triphosphate nucleotidohydrolase 

(dUTPase) that hydrolyzes dUTP to dUMP, the precursor of dTTP.



The annotated genome of D. discoideum identifies a gene encoding a 

polypeptide containing the five conserved motifs of homotrimeric dUTPases. 

Recombinant proteins, comprised of either full-length or core polypeptides with 

all conserved motifs but lacking residues 1-37 of the N-terminus, were active 

dUTPases. Crystallographic analyses of the core enzyme indicated that the 

C-termini, normally flexible, were constrained by interactions with the shortened 

N-termini that arose from the loss of residues 1-37. This allowed greater access 

of dUTP to active sites, resulting in enhanced catalytic parameters. A tagged 

protein comprised of the N-terminal forty amino acids of dUTPase fused to 

green fluorescent protein (GFP) was expressed in D. discoideum cells. 

Supporting a prediction of mitochondrial targeting information within the 

N-terminus, localization and subcellular fractionation studies showed GFP to 

be in mitochondria. N-terminal sequencing of immunoprecipitated GFP 

revealed the loss of the dUTPase sequence upon import into the organelle.





submitted by:  Catherine Chia  [[log in to unmask]]

——————————————————————————————————————





Wild Dictyostelium discoideum social amoebae show plastic responses to the 

presence of nonrelatives during multicellular development



Suegene Noh, Lauren Christopher, Joan E. Strassmann, David C. Queller



Department of Biology, Colby College, Waterville, Maine, USA 

Department of Biology, Washington University in St. Louis, St. Louis, Missouri, 

USA





Ecology and Evolution, in press (DOI:10.1002/ece3.5924)



When multiple strains of microbes form social groups, such as the multicellular 

fruiting bodies of Dictyostelium discoideum, conflict can arise regarding cell fate. 

Both fixed and plastic differences among strains can contribute to cell fate, and 

plastic responses may be particularly important if social environments frequently 

change. We used RNA-sequencing and photographic time series analysis to 

detect possible conflict-induced plastic differences between wild D. discoideum 

aggregates formed by single strains compared to mixed pairs of strains (chimeras). 

We found one hundred and two differentially expressed genes that were enriched 

for biological processes including cytoskeleton organization and cyclic-AMP 

response (up-regulated in chimeras), and DNA replication and cell cycle (down-

regulated in chimeras). In addition, our data indicate that in reference to a time 

series of multicellular development in the lab strain AX4, chimeras may be slightly 

behind clonal aggregates in their development. Finally, phenotypic analysis 

supported slower splitting of aggregates and a nonsignificant trend for larger 

group sizes in chimeras. The transcriptomic comparison and phenotypic analyses 

support discoordination among aggregate group members due to social conflict. 

These results are consistent with previously observed factors that affect cell fate 

decision in D. discoideum and provide evidence for plasticity in cAMP signaling 

and phenotypic coordination during development in response to social conflict in 

D. discoideum and similar microbial social groups.





submitted by:  Suegene Noh [[log in to unmask]]

==============================================================

[End dictyNews, volume 46, number 2]