RRC ID 56392
Author Marron AO, Ratcliffe S, Wheeler GL, Goldstein RE, King N, Not F, de Vargas C, Richter DJ.
Title The Evolution of Silicon Transport in Eukaryotes.
Journal Mol Biol Evol
Abstract Biosilicification (the formation of biological structures from silica) occurs in diverse eukaryotic lineages, plays a major role in global biogeochemical cycles, and has significant biotechnological applications. Silicon (Si) uptake is crucial for biosilicification, yet the evolutionary history of the transporters involved remains poorly known. Recent evidence suggests that the SIT family of Si transporters, initially identified in diatoms, may be widely distributed, with an extended family of related transporters (SIT-Ls) present in some nonsilicified organisms. Here, we identify SITs and SIT-Ls in a range of eukaryotes, including major silicified lineages (radiolarians and chrysophytes) and also bacterial SIT-Ls. Our evidence suggests that the symmetrical 10-transmembrane-domain SIT structure has independently evolved multiple times via duplication and fusion of 5-transmembrane-domain SIT-Ls. We also identify a second gene family, similar to the active Si transporter Lsi2, that is broadly distributed amongst siliceous and nonsiliceous eukaryotes. Our analyses resolve a distinct group of Lsi2-like genes, including plant and diatom Si-responsive genes, and sequences unique to siliceous sponges and choanoflagellates. The SIT/SIT-L and Lsi2 transporter families likely contribute to biosilicification in diverse lineages, indicating an ancient role for Si transport in eukaryotes. We propose that these Si transporters may have arisen initially to prevent Si toxicity in the high Si Precambrian oceans, with subsequent biologically induced reductions in Si concentrations of Phanerozoic seas leading to widespread losses of SIT, SIT-L, and Lsi2-like genes in diverse lineages. Thus, the origin and diversification of two independent Si transporter families both drove and were driven by ancient ocean Si levels.
Volume 33(12)
Pages 3226-3248
Published 2016-12-1
DOI 10.1093/molbev/msw209
PII msw209
PMID 27729397
PMC PMC5100055
MeSH Amino Acid Sequence Biological Evolution Biological Transport Carrier Proteins / genetics Carrier Proteins / metabolism Choanoflagellata / metabolism Diatoms / metabolism Eukaryota / metabolism* Evolution, Molecular Membrane Transport Proteins / genetics* Membrane Transport Proteins / metabolism Phylogeny Sequence Analysis, DNA Sequence Homology, Amino Acid Silicon / metabolism*
IF 14.797
Times Cited 29