Structural analysis of the G-box domain of the microcephaly protein CPAP suggests a role in centriole architecture.
Centrioles are evolutionarily conserved eukaryotic organelles composed of a protein scaffold surrounded by sets of microtubules organized with a 9-fold radial symmetry. CPAP, a centriolar protein essential for microtubule recruitment, features a C-terminal domain of unknown structure, the G-box. A missense mutation in the G-box reduces affinity for the centriolar shuttling protein STIL and causes primary microcephaly. Here, we characterize the molecular architecture of CPAP and determine the G-box structure alone and in complex with a STIL fragment. The G-box comprises a single elongated β sheet capable of forming supramolecular assemblies. Structural and biophysical studies highlight the conserved nature of the CPAP-STIL complex. We propose that CPAP acts as a horizontal "strut" that joins the centriolar scaffold with microtubules, whereas G-box domains form perpendicular connections.
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
Georgios N
GN
Hatzopoulos
Michèle C
MC
Erat
Erin
E
Cutts
Kacper B
KB
Rogala
Leanne M
LM
Slater
Philip J
PJ
Stansfeld
Ioannis
I
Vakonakis
D000818:Animals; D018797:Cell Cycle Proteins; D002502:Centrioles / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006801:Humans; D008831:Microcephaly / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D020125:Mutation, Missense; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000737:chemistry* / Q000235:genetics
D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; C522344:Stil protein, zebrafish; D029961:Zebrafish Proteins; C000588998:cenpj protein, zebrafish