Molecular Characterization of the SUMO-1 Modification of RanGAP1 and Its Role in Nuclear Envelope Association

Mahajan, Rohit; Gerace, Larry; Melchior, Frauke

doi:10.1083/jcb.140.2.259

Cited by 261 publications

(243 citation statements)

References 64 publications

Supporting

Mentioning

230

Contrasting

Order By: Relevance

“…Currently, the SUMO-1 function is still unclear (51)(52)(53). However, there are suggestions that SUMO-1 may be involved in targeting proteins to either the nuclear pore complexes in the nuclear envelope or nuclear bodies in the nucleus (36)(37)(38). The notion that SUMO-1 may be involved in targeting proteins to the nuclear pore complex came from studies of SUMO-1 conjugated RanGAP1 which is known to bind to the nuclear pore complex (24,37,39,40).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

SUMO-1 conjugation to topoisomerase I: A possible repair response to topoisomerase-mediated DNA damage

Mao¹,

Sun²,

Desai³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

187

148

View full text Add to dashboard Cite

Ubiquitin͞26S proteasome-dependent degradation of topoisomerase I (TOP1) has been suggested to be a unique repair response to TOP1-mediated DNA damage. In the current study, we show that treatment of mammalian cells or yeast cells expressing human DNA TOP1 with camptothecin (CPT) induces covalent modification of the TOP1 by SUMO-1͞Smt3p, a ubiquitin-like protein. This conclusion is based on the following observations: (i) Mammalian DNA TOP1 conjugates induced by CPT were cross-reactive with SUMO-1͞Smt3p-specific antibodies both in yeast expressing human DNA TOP1 as well as mammalian cells. (ii) The formation of TOP1 conjugates was shown to be dependent on UBC9, the E2 enzyme for SUMO-1͞Smt3p. (iii) TOP1 physically interacts with UBC9. (iv) Ubc9 mutant yeast cells expressing human DNA TOP1 was hypersensitive to CPT, suggesting that UBC9͞SUMO-1 may be involved in the repair of TOP1-mediated DNA damage.UBC9 ͉ Smt3p ͉ ubiquitin T opoisomerase-mediated DNA damage represents an unique type of DNA damage whose importance has become increasingly appreciated. Many antibiotics, anticancer drugs, toxins, carcinogens, and physiological stresses are known to abort the catalytic cycles of topoisomerases resulting in the formation of topoisomerase-mediated DNA damage (1-7). Despite its importance, little is known about the molecular basis for the repair of this unique type of DNA damage.Recent studies have demonstrated that topoisomerase I-(TOP1) mediated DNA damage activates a ubiquitin͞proteasome pathway, resulting in degradation of TOP1 (down-regulation of TOP1) (8). It has been speculated that this pathway may represent a unique repair mechanism for TOP1-mediated DNA damage because down-regulation of human TOP1 (hTOP1) is expected to result in resistance͞tolerance to TOP1 poisons (8).Human SUMO-1 (small ubiquitin-like modifier) is an 11-kDa protein that shares 18% sequence homology with ubiquitin (9-11). Smt3p, which is 48% identical to human SUMO-1, has been identified in yeast (12,13). SUMO-1͞Smt3p is activated by a heterodimeric E1 enzyme in both the yeast and mammalian systems (13)(14)(15). In addition, UBC9, an E2 enzyme, has been shown to specifically conjugate SUMO-1͞Smt3p to the target proteins (11,(16)(17)(18). Recently, an enzyme Ulp1p, which specifically cleaves proteins from SUMO-1͞Smt3p conjugates and is distinct from isopeptidases for ubiquitin conjugates, also has been identified in yeast (19). These results suggest that the SUMO-1͞Smt3p pathway is very similar to the ubiquitin pathway but distinct E1 and E2 enzymes as well as proteases are involved in these pathways. The biological function of the SUMO-1͞Smt3p pathway appears diverse. UBC9 was originally identified to play an essential function in G 2 -M cell cycle progression in yeast (20). However, UBC9 is also known to be important for DNA repair (21). It has been shown that SUMO-1 can be conjugated to a number of proteins such as PML (22), RanGAP1 (23, 24), I B␣ (25), FAS͞apolipoprotein-1 (26), p53 (27, 28), RAD51, and RAD52 (29). A growing number of pr...

show abstract

Section: Discussionmentioning

confidence: 99%

“…Whether the SUMO-1͞Smt3p pathway is involved in a common function for all these proteins remains unclear. However, SUMO-1 modification of RanGAP1 is known to cause RanGAP1 to bind to the nuclear pore complex (36)(37)(38). Other studies have demonstrated that SUMO-1 conjugates are often located in the nuclear bodies (39,40).…”

mentioning

confidence: 99%

SUMO-1 conjugation to topoisomerase I: A possible repair response to topoisomerase-mediated DNA damage

Mao¹,

Sun²,

Desai³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

187

148

View full text Add to dashboard Cite

show abstract

“…Secondary Structure Prediction-Secondary structure prediction was done using the PHD program on the entire sequences of RanGAP1, c-Jun, and PML and the first 100 amino acids of IB␣ (10,11,14,37). Sequences were deemed to be helical only when the program returned a probability value of Ն5 for two or more adjacent amino acid residues.…”

Section: Methodsmentioning

confidence: 99%

“…Secondary structure prediction based on primary sequences is successful in most cases, although the boundary of the secondary structures cannot be reliably predicted. Secondary structure prediction using the program PHD (43) indicates that the conjugation sites of known SUMO-1 target proteins RanGAP1, IB␣, AdE1B, c-Jun, and PML (10,11,14,37) are not in the predicted regular secondary structures such as ␣-helices or ␤-sheets, but in predicted loops (data not shown).…”

Section: Substrate Binding Site Mutants Of Ubc9 Affect the Transfer Omentioning

confidence: 99%

Identification of a Substrate Recognition Site on Ubc9

Lin¹,

Tatham²,

Yu³

et al. 2002

Journal of Biological Chemistry

115

100

View full text Add to dashboard Cite

Human Ubc9 is homologous to ubiquitin-conjugating enzymes. However, instead of conjugating ubiquitin, it conjugates a ubiquitin homologue, small ubiquitin-like modifier 1 (SUMO-1), also known as UBL1, GMP1, SMTP3, PIC1, and sentrin. The SUMO-1 conjugation pathway is very similar to that of ubiquitin with regard to the primary sequences of the ubiquitin-activating enzymes (E1), the three-dimensional structures of the ubiquitin-conjugating enzymes (E2), and the chemistry of the overall conjugation pathway. The interaction of substrates with Ubc9 has been studied using NMR spectroscopy. Peptides with sequences that correspond to those of the SUMO-1 conjugation sites from p53 and c-Jun both bind to a surface adjacent to the active site Cys 93 of human Ubc9, which has been previously shown to include residues that demonstrate the most significant dynamics on the microsecond to millisecond time scale. Mutations in this region, Q126A, Q130A, A131D, E132A, Y134A, and T135A, were constructed to evaluate the role of these residues in SUMO-1 conjugation. These alterations have significant effects on the conjugation of SUMO-1 with the target proteins p53, E1B, and promyelocytic leukemia protein and define a substrate binding site on Ubc9. Furthermore, the SUMO-1 conjugation site of p53 does not form any defined secondary structure when either free or bound to Ubc9. This suggests that a defined secondary structure at SUMO-1 conjugation sites in target proteins is not necessary for recognition and conjugation by the SUMO-1 pathway. SUMO-11 (also known as PIC1, sentrin, UBL1, SMTP3, and GMP1) is a ubiquitin homologue, and it has been shown to play an important role in cellular functions such as DNA repair and p53-dependent processes (for a review, see Ref. 1). The SUMO-1 and ubiquitin conjugation pathways share many similarities (for a review on ubiquitination, see Ref.2) in the primary structures of the activating enzymes (E1), the threedimensional structures of the conjugating enzymes (E2), and the mechanism of substrate modifications. In the SUMO-1 pathway, SUMO-1 is first activated by a heterodimeric SUMOactivating enzyme (SAE1/SAE2) (3-6) through hydrolysis of ATP to form a high energy thioester bond between the Cterminal Gly residue of SUMO-1 and a Cys residue in SAE2. Then, SUMO-1 is transferred to the SUMO-conjugating enzyme, Ubc9, in a transesterification reaction whereby the Cterminal Gly of SUMO-1 is conjugated to the SH group of the active site Cys 93 residue of Ubc9. In the final step, SUMO-1 is transferred from the SUMO-1⅐Ubc9 conjugate to the target protein. Similar to the ubiquitination pathway, the C-terminal Gly residue of the SUMO-1 molecule is involved in covalent linkage to the ⑀-amino group on a Lys residue of the target protein. At least in vitro, the SUMO-1 pathway does not appear to require the participation of activities equivalent to ubiquitinprotein isopeptide ligases (E3).The SUMO-1 pathway has diverse substrate proteins that include transcription factors (p53, c-Jun, and tramtrack), topoisomerases...

show abstract

“…Three groups independently showed that sumoylation is a prerequisite for the cytosolic RanGAP1 to associate with RanBP2 at the nuclear pore complex to form the functional nuclear import machinery (Matunis et al, 1996Mahajan et al, 1997Mahajan et al, , 1998Saitoh et al, 1998). Thus in this example, sumoylation alters the binding speci®city and hence the localization of the target protein.…”

Section: Rangap1: Substrate Re-targetingmentioning

confidence: 99%

SUMO: of branched proteins and nuclear bodies

2001

View full text Add to dashboard Cite

SUMO belongs to a growing number of ubiquitin-like proteins that covalently modify their target proteins. Although some evidence supports a role of SUMO modi®cation in regulating protein stability, most studied examples support a model by which SUMO alters the interaction properties of its targets, often a ecting their subcellular localization behavior. Examination of the PML nuclear bodies, whose principal components are SUMO-modi®ed, has revealed this modi®cation to be essential for their structural and functional integrity. This and other examples thus support the view that SUMO regulates the stability not of individual proteins, but rather that of entire multiprotein complexes. Oncogene (2001) 20, 7243 ± 7249.

show abstract

Molecular Characterization of the SUMO-1 Modification of RanGAP1 and Its Role in Nuclear Envelope Association

Cited by 261 publications

References 64 publications

SUMO-1 conjugation to topoisomerase I: A possible repair response to topoisomerase-mediated DNA damage

SUMO-1 conjugation to topoisomerase I: A possible repair response to topoisomerase-mediated DNA damage

Identification of a Substrate Recognition Site on Ubc9

SUMO: of branched proteins and nuclear bodies

Contact Info

Product

Resources

About