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Recognition of SUMO-modified PCNA requires tandem receptor motifs in Srs2.

Armstrong AA, Mohideen F, Lima CD - Nature (2012)

Bottom Line: It remains unclear how receptors such as Srs2 specifically recognize substrates after conjugation to Ub and Ubls.Here we show, through structural, biochemical and functional studies, that the Srs2 carboxy-terminal domain harbours tandem receptor motifs that interact independently with PCNA and SUMO and that both motifs are required to recognize SUMO-PCNA specifically.The mechanism presented is pertinent to understanding how other receptors specifically recognize Ub- and Ubl-modified substrates to facilitate signal transduction.

View Article: PubMed Central - PubMed

Affiliation: Structural Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA.

ABSTRACT
Ubiquitin (Ub) and ubiquitin-like (Ubl) modifiers such as SUMO (also known as Smt3 in Saccharomyces cerevisiae) mediate signal transduction through post-translational modification of substrate proteins in pathways that control differentiation, apoptosis and the cell cycle, and responses to stress such as the DNA damage response. In yeast, the proliferating cell nuclear antigen PCNA (also known as Pol30) is modified by ubiquitin in response to DNA damage and by SUMO during S phase. Whereas Ub-PCNA can signal for recruitment of translesion DNA polymerases, SUMO-PCNA signals for recruitment of the anti-recombinogenic DNA helicase Srs2. It remains unclear how receptors such as Srs2 specifically recognize substrates after conjugation to Ub and Ubls. Here we show, through structural, biochemical and functional studies, that the Srs2 carboxy-terminal domain harbours tandem receptor motifs that interact independently with PCNA and SUMO and that both motifs are required to recognize SUMO-PCNA specifically. The mechanism presented is pertinent to understanding how other receptors specifically recognize Ub- and Ubl-modified substrates to facilitate signal transduction.

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Models for Srs2/SUMO-PCNA complexesModels for SUMO conformations to enable simultaneous interaction with the SIM and PIP-like motif when attached to PCNA K164 (left) or K127 (right). Models generated required a simple rotation of SUMO at the isopeptide linkage for SUMOK164-PCNA and a slight rotation and translation of SUMO from a symmetry related complex to mimic SUMOK127-PCNA (Supplemental Fig. 13).
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Figure 5: Models for Srs2/SUMO-PCNA complexesModels for SUMO conformations to enable simultaneous interaction with the SIM and PIP-like motif when attached to PCNA K164 (left) or K127 (right). Models generated required a simple rotation of SUMO at the isopeptide linkage for SUMOK164-PCNA and a slight rotation and translation of SUMO from a symmetry related complex to mimic SUMOK127-PCNA (Supplemental Fig. 13).

Mentions: Models were generated for SUMOK164-PCNAtri and SUMOK127-PCNAtri to permit simultaneous engagement of the Srs2 SIM and PIP elements with PCNA and SUMO in a single protomer (Fig. 5 and Supplemental Fig. 13b). These models suggest that SUMO would adopt conformations distinct from that observed in most SUMO-PCNA structures where SUMO interacts with PCNA loop 184–198. Consistent with our models, FP data show that V186D and MEH188–190AAA mutations in PCNA loop 184–198, substitutions predicted to disrupt non-covalent contacts between SUMO and PCNA, have no impact on Srs2’s ability to interact with SUMOK164-PCNA (Supplemental Table 1).


Recognition of SUMO-modified PCNA requires tandem receptor motifs in Srs2.

Armstrong AA, Mohideen F, Lima CD - Nature (2012)

Models for Srs2/SUMO-PCNA complexesModels for SUMO conformations to enable simultaneous interaction with the SIM and PIP-like motif when attached to PCNA K164 (left) or K127 (right). Models generated required a simple rotation of SUMO at the isopeptide linkage for SUMOK164-PCNA and a slight rotation and translation of SUMO from a symmetry related complex to mimic SUMOK127-PCNA (Supplemental Fig. 13).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3306252&req=5

Figure 5: Models for Srs2/SUMO-PCNA complexesModels for SUMO conformations to enable simultaneous interaction with the SIM and PIP-like motif when attached to PCNA K164 (left) or K127 (right). Models generated required a simple rotation of SUMO at the isopeptide linkage for SUMOK164-PCNA and a slight rotation and translation of SUMO from a symmetry related complex to mimic SUMOK127-PCNA (Supplemental Fig. 13).
Mentions: Models were generated for SUMOK164-PCNAtri and SUMOK127-PCNAtri to permit simultaneous engagement of the Srs2 SIM and PIP elements with PCNA and SUMO in a single protomer (Fig. 5 and Supplemental Fig. 13b). These models suggest that SUMO would adopt conformations distinct from that observed in most SUMO-PCNA structures where SUMO interacts with PCNA loop 184–198. Consistent with our models, FP data show that V186D and MEH188–190AAA mutations in PCNA loop 184–198, substitutions predicted to disrupt non-covalent contacts between SUMO and PCNA, have no impact on Srs2’s ability to interact with SUMOK164-PCNA (Supplemental Table 1).

Bottom Line: It remains unclear how receptors such as Srs2 specifically recognize substrates after conjugation to Ub and Ubls.Here we show, through structural, biochemical and functional studies, that the Srs2 carboxy-terminal domain harbours tandem receptor motifs that interact independently with PCNA and SUMO and that both motifs are required to recognize SUMO-PCNA specifically.The mechanism presented is pertinent to understanding how other receptors specifically recognize Ub- and Ubl-modified substrates to facilitate signal transduction.

View Article: PubMed Central - PubMed

Affiliation: Structural Biology Program, Sloan-Kettering Institute, New York, New York 10065, USA.

ABSTRACT
Ubiquitin (Ub) and ubiquitin-like (Ubl) modifiers such as SUMO (also known as Smt3 in Saccharomyces cerevisiae) mediate signal transduction through post-translational modification of substrate proteins in pathways that control differentiation, apoptosis and the cell cycle, and responses to stress such as the DNA damage response. In yeast, the proliferating cell nuclear antigen PCNA (also known as Pol30) is modified by ubiquitin in response to DNA damage and by SUMO during S phase. Whereas Ub-PCNA can signal for recruitment of translesion DNA polymerases, SUMO-PCNA signals for recruitment of the anti-recombinogenic DNA helicase Srs2. It remains unclear how receptors such as Srs2 specifically recognize substrates after conjugation to Ub and Ubls. Here we show, through structural, biochemical and functional studies, that the Srs2 carboxy-terminal domain harbours tandem receptor motifs that interact independently with PCNA and SUMO and that both motifs are required to recognize SUMO-PCNA specifically. The mechanism presented is pertinent to understanding how other receptors specifically recognize Ub- and Ubl-modified substrates to facilitate signal transduction.

Show MeSH
Related in: MedlinePlus