Functional diversification of centrins and cell morphological complexity.
In addition to their key role in the duplication of microtubule organising centres (MTOCs), centrins are major constituents of diverse MTOC-associated contractile arrays. A centrin partner, Sfi1p, has been characterised in yeast as a large protein carrying multiple centrin-binding sites, suggesting a model for centrin-mediated Ca2+-induced contractility and for the duplication of MTOCs. In vivo validation of this model has been obtained in Paramecium, which possesses an extended contractile array - the infraciliary lattice (ICL) - essentially composed of centrins and a huge Sfi1p-like protein, PtCenBP1p, which is essential for ICL assembly and contractility. The high molecular diversity revealed here by the proteomic analysis of the ICL, including ten subfamilies of centrins and two subfamilies of Sf1p-like proteins, led us to address the question of the functional redundancy, either between the centrin-binding proteins or between the centrin subfamilies. We show that all are essential for ICL biogenesis. The two centrin-binding protein subfamilies and nine of the centrin subfamilies are ICL specific and play a role in its molecular and supramolecular architecture. The tenth and most conserved centrin subfamily is present at three cortical locations (ICL, basal bodies and contractile vacuole pores) and might play a role in coordinating duplication and positioning of cortical organelles.
CNRS, Centre de Génétique Moléculaire, UPR 2167, Gif-sur-Yvette, F-91198, France. gogendeau@cgm.cnrs-gif.fr
Delphine
D
Gogendeau
Catherine
C
Klotz
Olivier
O
Arnaiz
Agata
A
Malinowska
Michal
M
Dadlez
Nicole Garreau
NG
de Loubresse
Françoise
F
Ruiz
France
F
Koll
Janine
J
Beisson
D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000145:classification / Q000378:metabolism; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D049452:Green Fluorescent Proteins / Q000235:genetics; D013058:Mass Spectrometry; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D005810:Multigene Family; D016805:Paramecium tetraurelia / Q000166:cytology* / Q000235:genetics / Q000502:physiology; D010802:Phylogeny; D011485:Protein Binding; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins