King, N. et al. The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans. Nature 451, 783-788

Department of Molecular and Cell Biology and the Center for Integrative Genomics, University of California, Berkeley, California 94720, USA.
Nature (Impact Factor: 41.46). 02/2008; 451(7180):783-788. DOI: 10.1038/nature06617


Choanoflagellates are the closest known relatives of metazoans. To discover potential molecular mechanisms underlying the evolution of metazoan multicellularity, we sequenced and analysed the genome of the unicellular choanoflagellate Monosiga brevicollis. The genome contains approximately 9,200 intron-rich genes, including a number that encode cell adhesion and signalling protein domains that are otherwise restricted to metazoans. Here we show that the physical linkages among protein domains often differ between M. brevicollis and metazoans, suggesting that abundant domain shuffling followed the separation of the choanoflagellate and metazoan lineages. The completion of the M. brevicollis genome allows us to reconstruct with increasing resolution the genomic changes that accompanied the origin of metazoans.

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    • "(A) Choanoflagellates are the closest living relatives of metazoans (Carr et al., 2008; King et al., 2008; Richter and King, 2013; Ruiz-Trillo et al., 2008 "
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    ABSTRACT: The origin of neurons was a key event in evolution, allowing metazoans to evolve rapid behavioral responses to environmental cues. Reconstructing the origin of synaptic proteins promises to reveal their ancestral functions and might shed light on the evolution of the first neuron-like cells in metazoans. By analyzing the genomes of diverse metazoans and their closest relatives, the evolutionary history of diverse presynaptic and postsynaptic proteins has been reconstructed. These analyses revealed that choanoflagellates, the closest relatives of metazoans, possess diverse synaptic protein homologs. Recent studies have now begun to investigate their ancestral functions. A primordial neurosecretory apparatus in choanoflagellates was identified and it was found that the mechanism, by which presynaptic proteins required for secretion of neurotransmitters interact, is conserved in choanoflagellates and metazoans. Moreover, studies on the postsynaptic protein homolog Homer revealed unexpected localization patterns in choanoflagellates and new binding partners, both which are conserved in metazoans. These findings demonstrate that the study of choanoflagellates can uncover ancient and previously undescribed functions of synaptic proteins. © 2015. Published by The Company of Biologists Ltd.
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    • "Regarding the components responsible for cell surface attachment, certain adhesion receptor families like integrins, syndecan and glypican membrane proteoglycans and CD36 are also present in sponges and all metazoa (Brower et al, 1997; Chakravarti and Adams, 2006; Filmus et al., 2008; Hughes, 2001; Mü ller et al., 2004); nevertheless, some of these molecules probably exert different functions besides cell adhesion and attachment in certain organisms. Interestingly, the high conservation of core adhesome components has raised the possibility of their evolutionary origins outside the metazoa (King et al., 2008; Rokas, 2008). Moreover, the ECM proteases MMPs (matrix metalloproteinases) and ADAMTS (metalloproteinase with thrombospondin repeats proteases) are known to be important for ECM organization and remodeling and few studies have shown that they are also conserved throughout the metazoa (Fanjul-Fernández et al., 2010; Nicholson et al., 2005). "
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    Reference Module in Biomedical Research, 01/2015: chapter Cell-Matrix Interactions;
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    • "2). In the genome of another choanoflagellate, Monosiga brevicollis (King et al. 2008), we could detect only a short gene fragment encoding a partial Ca v of only 258 amino acids, suggesting either a partial gene deletion or a technical problem in genome assembly at this specific region (data not shown). "
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