Format

Send to

Choose Destination
J Mol Biol. 2016 Mar 27;428(6):1256-1271. doi: 10.1016/j.jmb.2015.10.002. Epub 2015 Oct 22.

Multiple Weak Linear Motifs Enhance Recruitment and Processivity in SPOP-Mediated Substrate Ubiquitination.

Author information

1
Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
2
Molecular Interactions Analysis Shared Resource, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
3
Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Department of Microbiology, Immunology, and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38105, USA.
4
St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
5
Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
6
Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Howard Hughes Medical Institute, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
7
Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA. Electronic address: tanja.mittag@stjude.org.

Abstract

Primary sequence motifs, with millimolar affinities for binding partners, are abundant in disordered protein regions. In multivalent interactions, such weak linear motifs can cooperate to recruit binding partners via avidity effects. If linear motifs recruit modifying enzymes, optimal placement of weak motifs may regulate access to modification sites. Weak motifs may thus exert physiological relevance stronger than that suggested by their affinities, but molecular mechanisms of their function are still poorly understood. Herein, we use the N-terminal disordered region of the Hedgehog transcriptional regulator Gli3 (Gli3(1-90)) to determine the role of weak motifs encoded in its primary sequence for the recruitment of its ubiquitin ligase CRL3(SPOP) and the subsequent effect on ubiquitination efficiency. The substrate adaptor SPOP binds linear motifs through its MATH (meprin and TRAF homology) domain and forms higher-order oligomers through its oligomerization domains, rendering SPOP multivalent for its substrates. Gli3 has multiple weak SPOP binding motifs. We map three such motifs in Gli3(1-90), the weakest of which has a millimolar dissociation constant. Multivalency of ligase and substrate for each other facilitates enhanced ligase recruitment and stimulates Gli3(1-90) ubiquitination in in vitro ubiquitination assays. We speculate that the weak motifs enable processivity through avidity effects and by providing steric access to lysine residues that are otherwise not prioritized for polyubiquitination. Weak motifs may generally be employed in multivalent systems to act as gatekeepers regulating post-translational modification.

KEYWORDS:

NMR spectroscopy; Speckle-type POZ protein; cancer; degron; multivalency

PMID:
26475525
PMCID:
PMC4826287
DOI:
10.1016/j.jmb.2015.10.002
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center