Proteomic analysis of isolated chlamydomonas centrioles reveals orthologs of ciliary-disease genes.
BACKGROUND
The centriole is one of the most enigmatic organelles in the cell. Centrioles are cylindrical, microtubule-based barrels found in the core of the centrosome. Centrioles also act as basal bodies during interphase to nucleate the assembly of cilia and flagella. There are currently only a handful of known centriole proteins.


RESULTS
We used mass-spectrometry-based MudPIT (multidimensional protein identification technology) to identify the protein composition of basal bodies (centrioles) isolated from the green alga Chlamydomonas reinhardtii. This analysis detected the majority of known centriole proteins, including centrin, epsilon tubulin, and the cartwheel protein BLD10p. By combining proteomic data with information about gene expression and comparative genomics, we identified 45 cross-validated centriole candidate proteins in two classes. Members of the first class of proteins (BUG1-BUG27) are encoded by genes whose expression correlates with flagellar assembly and which therefore may play a role in ciliogenesis-related functions of basal bodies. Members of the second class (POC1-POC18) are implicated by comparative-genomics and -proteomics studies to be conserved components of the centriole. We confirmed centriolar localization for the human homologs of four candidate proteins. Three of the cross-validated centriole candidate proteins are encoded by orthologs of genes (OFD1, NPHP-4, and PACRG) implicated in mammalian ciliary function and disease, suggesting that oral-facial-digital syndrome and nephronophthisis may involve a dysfunction of centrioles and/or basal bodies.


CONCLUSIONS
By analyzing isolated Chlamydomonas basal bodies, we have been able to obtain the first reported proteomic analysis of the centriole.
Keller
Lani C
LC
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA.
Romijn
Edwin P
EP
Zamora
Ivan
I
Yates
John R
JR
Marshall
Wallace F
WF
D000595:Amino Acid Sequence; D000818:Animals; D002502:Centrioles / Q000235:genetics*; D002696:Chlamydomonas / Q000235:genetics*; D002923:Cilia / Q000235:genetics* / Q000473:pathology; D017124:Conserved Sequence; D006801:Humans; D007674:Kidney Diseases / Q000235:genetics; D008840:Microfilament Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins / Q000235:genetics; D009958:Orofaciodigital Syndromes / Q000235:genetics; D011506:Proteins / Q000235:genetics; D040901:Proteomics / Q000379:methods*; D015800:Protozoan Proteins / Q000032:analysis / Q000235:genetics*; D015203:Reproducibility of Results
D008840:Microfilament Proteins; D018832:Molecular Chaperones; C491578:NPHP4 protein, human; D009687:Nuclear Proteins; C115130:OFD1 protein, human; C471711:PACRG protein, human; D011506:Proteins; D015800:Protozoan Proteins