Tubulin tyrosine ligase structure reveals adaptation of an ancient fold to bind and modify tubulin.
Tubulin tyrosine ligase (TTL) catalyzes the post-translational C-terminal tyrosination of α-tubulin. Tyrosination regulates recruitment of microtubule-interacting proteins. TTL is essential. Its loss causes morphogenic abnormalities and is associated with cancers of poor prognosis. We present the first crystal structure of TTL (from Xenopus tropicalis), defining the structural scaffold upon which the diverse TTL-like family of tubulin-modifying enzymes is built. TTL recognizes tubulin using a bipartite strategy. It engages the tubulin tail through low-affinity, high-specificity interactions, and co-opts what is otherwise a homo-oligomerization interface in structurally related ATP grasp-fold enzymes to form a tight hetero-oligomeric complex with the tubulin body. Small-angle X-ray scattering and functional analyses reveal that TTL forms an elongated complex with the tubulin dimer and prevents its incorporation into microtubules by capping the tubulin longitudinal interface, possibly modulating the partition of tubulin between monomeric and polymeric forms.
Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA.
Agnieszka
A
Szyk
Alexandra M
AM
Deaconescu
Grzegorz
G
Piszczek
Antonina
A
Roll-Mecak
D000818:Animals; D018360:Crystallography, X-Ray; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010453:Peptide Synthases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism*; D029867:Xenopus Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D014404:Tubulin; D029867:Xenopus Proteins; D010453:Peptide Synthases; C023213:tyrosyltubulin ligase