Synthetic peptides identify the minimal substrate requirements of tubulin polyglutamylase in side chain elongation.
The minimal sequence requirement of Crithidia tubulin polyglutamylase is already fulfilled by tubulin-related peptides carrying a free alpha-carboxylate on a glutamic acid residue. Since the product of each glutamylation step fulfills the substrate requirements necessary for the next cycle, very long side chains are generated with brain tubulin as a substrate. Up to 70 mol of glutamic acid was incorporated per alphabeta-heterodimer. We speculate that the strict choice of a particular glutamate residue for the formation of the isopeptide bond initiating a novel side chain is made by a tubulin monoglutamylase which requires the entire tubulin as substrate.
Westermann
S
S
Max Planck Institute for Biophysical Chemistry, Department of Biochemistry, Am Fassberg 11, 37077, Goettingen, Germany.
Plessmann
U
U
Weber
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D016831:Crithidia fasciculata / Q000201:enzymology*; D015151:Immunoblotting; D008969:Molecular Sequence Data; D010453:Peptide Synthases; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism; D011099:Polyglutamic Acid / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014404:Tubulin / Q000138:chemical synthesis / Q000378:metabolism*
D010455:Peptides; D014404:Tubulin; D011099:Polyglutamic Acid; D010453:Peptide Synthases; C112698:tubulin polyglutamylase