Characterization of C. elegans RING finger protein 1, a binding partner of ubiquitin-conjugating enzyme 1

ABSTRACT RNF5 is a RING finger protein found to be important in the growth and development of Caenorhabditis elegans. The search for RNF5-associated proteins via a yeast two-hybrid screen identified a LIM-containing protein in C. elegans which shows homology with human paxillin. Here we demonstrate that the human homologue of RNF5 associates with the amino-terminal domain of paxillin, resulting in its ubiquitination. RNF5 requires intact RING and C-terminal domains to mediate paxillin ubiquitination. Whereas RNF5 mediates efficient ubiquitination of paxillin in vivo, protein extracts were required for in vitro ubiquitination, suggesting that additional modifications and/or an associated E3 ligase assist RNF5 targeting of paxillin ubiquitination. Mutant Ubc13 efficiently inhibits RNF5 ubiquitination, suggesting that RNF5 generates polychain ubiquitin of the K63 topology. Expression of RNF5 increases the cytoplasmic distribution of paxillin while decreasing its localization within focal adhesions, where it is primarily seen under normal growth. Concomitantly, RNF5 expression results in inhibition of cell motility. Via targeting of paxillin ubiquitination, which alters its localization, RNF5 emerges as a novel regulator of cell motility.

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Screen for multi-SUMO–binding proteins reveals a multi-SIM–binding mechanism for recruitment of the transcriptional regulator ZMYM2 to chromatin

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1509716112 ◽

2015 ◽

Vol 112 (35) ◽

pp. E4854-E4863 ◽

Cited By ~ 21

Author(s):

Elisa Aguilar-Martinez ◽

Xi Chen ◽

Aaron Webber ◽

A. Paul Mould ◽

Anne Seifert ◽

...

Keyword(s):

Transcriptional Control ◽

Ring Finger ◽

Binding Activity ◽

Ring Finger Protein ◽

E3 Ligases ◽

Binding Partner ◽

Finger Protein ◽

Sumo Binding Proteins ◽

Nuclear Processes ◽

Regulatory Event

Protein SUMOylation has emerged as an important regulatory event, particularly in nuclear processes such as transcriptional control and DNA repair. In this context, small ubiquitin-like modifier (SUMO) often provides a binding platform for the recruitment of proteins via their SUMO-interacting motifs (SIMs). Recent discoveries point to an important role for multivalent SUMO binding through multiple SIMs in the binding partner as exemplified by poly-SUMOylation acting as a binding platform for ubiquitin E3 ligases such as ring finger protein 4. Here, we have investigated whether other types of protein are recruited through multivalent SUMO interactions. We have identified dozens of proteins that bind to multi-SUMO platforms, thereby uncovering a complex potential regulatory network. Multi-SUMO binding is mediated through multi-SIM modules, and the functional importance of these interactions is demonstrated for the transcriptional corepressor ZMYM2/ZNF198 where its multi-SUMO–binding activity is required for its recruitment to chromatin.

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