dictyNews
Electronic Edition
Volume 49, number 6
February 24, 2023

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=========
Abstracts
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Phylogeny-wide analysis of G-protein coupled receptors in social 
amoebas and implications for the evolution of multicellularity 
[version 2; peer review: 2 approved]

Grant Hall, Sarah Kelly, Pauline Schaap, Christina Schilde

Open Res Europe 2023, 2:134
(https://doi.org/10.12688/openreseurope.15250.2)

G-protein coupled receptors (GPCRs) are seven-transmembrane 
proteins and constitute the largest group of receptors within 
eukaryotes. The presence of a large set of GPCRs in the unicellular 
Amoebozoa was surprising and is indicative of the largely undiscovered 
environmental sensing capabilities in this group. Evolutionary transitions 
from unicellular to multicellular lifestyles, like we see in social amoebas, 
have occurred several times independently in the Amoebozoa, and 
GPCRs may have been co-opted for new functions in cell-cell 
communication.

Methods
We have analysed a set of GPCRs from fully sequenced Amoebozoan 
genomes by Bayesian inference, compared their phylogenetic 
distribution and domain composition, and analysed their temporal 
and spatial expression patterns in five species of dictyostelids.

Results
We found evidence that most GPCRs are conserved deeply in the 
Amoebozoa and are probably performing roles in general cell functions 
and complex environmental sensing. All families of GPCRs (apart from 
the family 4 fungal pheromone receptors) are present in dictyostelids 
with family 5 being the largest and family 2 the one with the fewest 
members. For the first time, we identify the presence of family 1 
rhodopsin-like GPCRs in dictyostelids. Some GPCRs have been 
amplified in the dictyostelids and in specific lineages thereof and 
through changes in expression patterns may have been repurposed 
for signalling in multicellular development.

Discussion
Our phylogenetic analysis suggests that GPCR families 1, 2 and 6 already 
diverged early in the Amoebozoa, whereas families 3 and 5 expanded 
later within the dictyostelids. The family 6 cAMP receptors that have 
experimentally supported roles in multicellular development in dictyostelids 
(carA-carD; tasA/B) originated at the root of all dictyostelids and only have 
weakly associated homologs in Physarum polycephalum. Our analysis 
identified candidate GPCRs which have evolved in the dictyostelids and 
could have been co-opted for multicellular development.


Submitted by Christina Schilde [[log in to unmask]]
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[End dictyNews, volume 49, number 6]