Ligases;
Forming carbon-nitrogen bonds;
Acid-D-amino-acid ligases (peptide synthases)
BRITE hierarchy

[beta-tubulin]-L-glutamate:L-glutamate ligase (ADP-forming)

n ATP + [beta-tubulin]-L-glutamate + n L-glutamate = [beta-tubulin]-(gamma-(poly-alpha-L-glutamyl)-L-glutamyl)-L-glutamate + n ADP + n phosphate (overall reaction);
(1a) ATP + [beta-tubulin]-L-glutamate + L-glutamate = [beta-tubulin]-(gamma-L-glutamyl)-L-glutamate + ADP + phosphate;
(1b) ATP + [beta-tubulin]-(gamma-L-glutamyl)-L-glutamate + L-glutamate = [beta-tubulin]-(alpha-L-glutamyl-gamma-L-glutamyl)-L-glutamate + ADP + phosphate;
(1c) ATP + [beta-tubulin]-(alpha-L-glutamyl-gamma-L-glutamyl)-L-glutamate + n L-glutamate = [beta-tubulin]-(gamma-(poly-alpha-L-glutamyl)-L-glutamyl)-L-glutamate + n ADP + n phosphate

ATP [CPD:C00002];
[beta-tubulin]-L-glutamate;
L-glutamate [CPD:C00025];
[beta-tubulin]-(gamma-L-glutamyl)-L-glutamate;
[beta-tubulin]-(alpha-L-glutamyl-gamma-L-glutamyl)-L-glutamate

The eukaryotic tubulin proteins, which polymerize into microtubules, are highly modified by the addition of side-chains. The polyglutamylation reaction catalysed by this group of enzymes consists of two biochemically distinct steps: initiation and elongation. Initiation comprises the formation of an isopeptide bond with the gamma-carboxyl group of the glutamate acceptor site, whereas elongation consists of the addition of glutamate residues linked by regular peptide bonds to the gamma-linked residue. This entry describes enzymes that act on beta-tubulins and other proteins with glutamate-rich regions but not on alpha-tubulins.

EC 6.3.2.62 created 2021

1  [PMID:9622491]

2  [PMID:10564646]

3  [PMID:16901895]

4  [PMID:18045879]