PDBsum entry 6bk5

Signaling protein

PDB id: 6bk5

Contents

Protein chain

323 a.a.

Metals

_CA

Waters ×139

PDB id:

6bk5

Name:

Signaling protein

Title:

Inactive choanoflagellate e3 ubiquitin ligase cbl tkb

Structure:

Ubiquitin ligase cbl. Chain: a. Engineered: yes

Source:

Salpingoeca rosetta (strain atcc 50818 / bsb- 021). Organism_taxid: 946362. Strain: atcc 50818 / bsb-021. Gene: ptsg_09506. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.40Å R-factor: 0.169 R-free: 0.209

Authors:

J.F.Amacher,J.Kuriyan

Key ref:

J.F.Amacher et al. (2018). Phosphorylation control of the ubiquitin ligase Cbl is conserved in choanoflagellates. Protein Sci, 27, 923-932. PubMed id: 29498112 DOI: 10.1002/pro.3397

Date:

07-Nov-17 Release date: 14-Mar-18

Protein chain

F2UL73  (F2UL73_SALR5) -  RING-type E3 ubiquitin transferase from Salpingoeca rosetta (strain ATCC 50818 / BSB-021)

Seq: 553 a.a.

Struc: 323 a.a.

Enzyme reactions

• Enzyme class: E.C.2.3.2.27 - RING-type E3 ubiquitin transferase.
• Reaction: S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N₆- ubiquitinyl-[acceptor protein]-L-lysine

DOI no: 10.1002/pro.3397

Protein Sci 27:923-932 (2018)

PubMed id: 29498112

Phosphorylation control of the ubiquitin ligase Cbl is conserved in choanoflagellates.

J.F.Amacher, H.T.Hobbs, A.C.Cantor, L.Shah, M.J.Rivero, S.A.Mulchand, J.Kuriyan.

ABSTRACT

Cbl proteins are E3 ubiquitin ligases specialized for the regulation of tyrosine kinases by ubiquitylation. Human Cbl proteins are activated by tyrosine phosphorylation, thus setting up a feedback loop whereby the activation of tyrosine kinases triggers their own degradation. Cbl proteins are targeted to their substrates by a phosphotyrosine-binding SH2 domain. Choanoflagellates, unicellular eukaryotes that are closely related to metazoans, also contain Cbl. The tyrosine kinase complement of choanoflagellates is distinct from that of metazoans, and it is unclear if choanoflagellate Cbl is regulated similarly to metazoan Cbl. Here, we performed structure-function studies on Cbl from the choanoflagellate species Salpingoeca rosetta and found that it undergoes phosphorylation-dependent activation. We show that S. rosetta Cbl can be phosphorylated by S. rosetta Src kinase, and that it can ubiquitylate S. rosetta Src. We also compared the substrate selectivity of human and S. rosetta Cbl by measuring ubiquitylation of Src constructs in which Cbl-recruitment sites are placed in different contexts with respect to the kinase domain. Our results indicate that for both human and S. rosetta Cbl, ubiquitylation depends on proximity and accessibility, rather than being targeted toward specific lysine residues. Our results point to an ancient interplay between phosphotyrosine and ubiquitin signaling in the metazoan lineage.