TY - JOUR
T1 - Three-dimensional flagella structures from animals’ closest unicellular relatives, the Choanoflagellates
AU - Pinskey, Justine M.
AU - Lagisetty, Adhya
AU - Gui, Long
AU - Phan, Nhan
AU - Reetz, Evan
AU - Tavakoli, Amirrasoul
AU - Fu, Gang
AU - Nicastro, Daniela
N1 - Publisher Copyright:
© Pinskey et al.
PY - 2022/11
Y1 - 2022/11
N2 - In most eukaryotic organisms, cilia and flagella perform a variety of life-sustaining roles related to environmental sensing and motility. Cryo-electron microscopy has provided considerable insight into the morphology and function of flagellar structures, but studies have been limited to lesthan a dozen of the millions of known eukaryotic species. Ultrastructural information is particularly lacking for unicellular organisms in the Opisthokonta clade, leaving a sizeable gap in our under-standing of flagella evolution between unicellular species and multicellular metazoans (animals). Choanoflagellates are important aquatic heterotrophs, uniquely positioned within the opisthokonts as the metazoans’ closest living unicellular relatives. We performed cryo-focused ion beam milling and cryo-electron tomography on flagella from the choanoflagellate species Salpingoeca rosetta. Wshow that the axonemal dyneins, radial spokes, and central pair complex in S. rosetta more closely resemble metazoan structures than those of unicellular organisms from other suprakingdoms. In addition, we describe unique features of S. rosetta flagella, including microtubule holes, microtubule inner proteins, and the flagellar vane: a fine, net-like extension that has been notoriously difficult to visualize using other methods. Furthermore, we report barb-like structures of unknown function on the extracellular surface of the flagellar membrane. Together, our findings provide new insights into choanoflagellate biology and flagella evolution between unicellular and multicellular opisthokonts.
AB - In most eukaryotic organisms, cilia and flagella perform a variety of life-sustaining roles related to environmental sensing and motility. Cryo-electron microscopy has provided considerable insight into the morphology and function of flagellar structures, but studies have been limited to lesthan a dozen of the millions of known eukaryotic species. Ultrastructural information is particularly lacking for unicellular organisms in the Opisthokonta clade, leaving a sizeable gap in our under-standing of flagella evolution between unicellular species and multicellular metazoans (animals). Choanoflagellates are important aquatic heterotrophs, uniquely positioned within the opisthokonts as the metazoans’ closest living unicellular relatives. We performed cryo-focused ion beam milling and cryo-electron tomography on flagella from the choanoflagellate species Salpingoeca rosetta. Wshow that the axonemal dyneins, radial spokes, and central pair complex in S. rosetta more closely resemble metazoan structures than those of unicellular organisms from other suprakingdoms. In addition, we describe unique features of S. rosetta flagella, including microtubule holes, microtubule inner proteins, and the flagellar vane: a fine, net-like extension that has been notoriously difficult to visualize using other methods. Furthermore, we report barb-like structures of unknown function on the extracellular surface of the flagellar membrane. Together, our findings provide new insights into choanoflagellate biology and flagella evolution between unicellular and multicellular opisthokonts.
UR - http://www.scopus.com/inward/record.url?scp=85142161108&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85142161108&partnerID=8YFLogxK
U2 - 10.7554/eLife.78133
DO - 10.7554/eLife.78133
M3 - Article
C2 - 36384644
AN - SCOPUS:85142161108
SN - 2050-084X
VL - 11
JO - eLife
JF - eLife
M1 - e78133
ER -