Limits...
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.

Show MeSH

Related in: MedlinePlus

Srs2 PIP-like motif and SIM interactions with PCNA and SUMOa, Sequence alignment for Srs2 CTD (amino acids 1149–1174) above p21, Polη and Polι PIP-box motifs and DAXX, PIASx and RanBP2 SIMs. PIP-box consensus motif numbered above Srs2 (Q=glutamine, x=any amino acid, h=hydrophobic, a=aromatic). Amino acids similar to consensus are highlighted (green). Hydrophobic and acidic residues highlighted blue and pink for SIMs. b, Srs2 PIP-like motif (pink), PCNA colored as in Fig 2. PCNA, Srs2 and select amino acids labeled by numbered single letter code. Hydrogen bonds as dashed lines. c, Srs2 SIM (pink) and SUMO (green) as in b.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3306252&req=5

Figure 3: Srs2 PIP-like motif and SIM interactions with PCNA and SUMOa, Sequence alignment for Srs2 CTD (amino acids 1149–1174) above p21, Polη and Polι PIP-box motifs and DAXX, PIASx and RanBP2 SIMs. PIP-box consensus motif numbered above Srs2 (Q=glutamine, x=any amino acid, h=hydrophobic, a=aromatic). Amino acids similar to consensus are highlighted (green). Hydrophobic and acidic residues highlighted blue and pink for SIMs. b, Srs2 PIP-like motif (pink), PCNA colored as in Fig 2. PCNA, Srs2 and select amino acids labeled by numbered single letter code. Hydrogen bonds as dashed lines. c, Srs2 SIM (pink) and SUMO (green) as in b.

Mentions: The Srs2 PCNA interaction motif differs from canonical PIP-box motifs6–8,21,28,29, perhaps consistent with its not being described previously. Most PIP-boxes contain a core QxxΨ motif followed by two conserved aromatic residues 3 and 4 residues C-terminal of the core motif (Fig. 3a and Supplemental Fig. 9). Srs2 residues 1149–1152 (QMDI) conform to a canonical PIP-box motif (QxxΨ), but Srs2 residues 1153–1161 lack the conserved aromatic residues. In addition, most PIP-boxes adopt a 310 helix after the QxxΨ motif while Srs2 residues 1153–1161 adopt two turns of α-helix that project Q1155 and L1156 into the PCNA surface (Fig 3b).


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

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

Srs2 PIP-like motif and SIM interactions with PCNA and SUMOa, Sequence alignment for Srs2 CTD (amino acids 1149–1174) above p21, Polη and Polι PIP-box motifs and DAXX, PIASx and RanBP2 SIMs. PIP-box consensus motif numbered above Srs2 (Q=glutamine, x=any amino acid, h=hydrophobic, a=aromatic). Amino acids similar to consensus are highlighted (green). Hydrophobic and acidic residues highlighted blue and pink for SIMs. b, Srs2 PIP-like motif (pink), PCNA colored as in Fig 2. PCNA, Srs2 and select amino acids labeled by numbered single letter code. Hydrogen bonds as dashed lines. c, Srs2 SIM (pink) and SUMO (green) as in b.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Srs2 PIP-like motif and SIM interactions with PCNA and SUMOa, Sequence alignment for Srs2 CTD (amino acids 1149–1174) above p21, Polη and Polι PIP-box motifs and DAXX, PIASx and RanBP2 SIMs. PIP-box consensus motif numbered above Srs2 (Q=glutamine, x=any amino acid, h=hydrophobic, a=aromatic). Amino acids similar to consensus are highlighted (green). Hydrophobic and acidic residues highlighted blue and pink for SIMs. b, Srs2 PIP-like motif (pink), PCNA colored as in Fig 2. PCNA, Srs2 and select amino acids labeled by numbered single letter code. Hydrogen bonds as dashed lines. c, Srs2 SIM (pink) and SUMO (green) as in b.
Mentions: The Srs2 PCNA interaction motif differs from canonical PIP-box motifs6–8,21,28,29, perhaps consistent with its not being described previously. Most PIP-boxes contain a core QxxΨ motif followed by two conserved aromatic residues 3 and 4 residues C-terminal of the core motif (Fig. 3a and Supplemental Fig. 9). Srs2 residues 1149–1152 (QMDI) conform to a canonical PIP-box motif (QxxΨ), but Srs2 residues 1153–1161 lack the conserved aromatic residues. In addition, most PIP-boxes adopt a 310 helix after the QxxΨ motif while Srs2 residues 1153–1161 adopt two turns of α-helix that project Q1155 and L1156 into the PCNA surface (Fig 3b).

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