TY - JOUR
T1 - Systematic identification and analysis of mammalian small ubiquitin-like modifier substrates
AU - Gocke, Christian B.
AU - Yu, Hongtao
AU - Kang, Jungseog
PY - 2005/2/11
Y1 - 2005/2/11
N2 - Small ubiquitin-like modifier (SUMO) regulates diverse cellular processes through its reversible, covalent attachment to target proteins. Many SUMO substrates are involved in transcription and chromatin structure. Sumoylation appears to regulate the functions of target proteins by changing their subcellular localization, increasing their stability, and/or mediating their binding to other proteins. Using an in vitro expression cloning approach, we have identified 40 human SUMO1 substrates. The spectrum of human SUMO1 substrates identified in our screen suggests general roles of sumoylation in transcription, chromosome structure, and RNA processing. We have validated the sumoylation of 24 substrates in living cells. Analysis of this panel of SUMO substrates leads to the following observations. 1) Sumoylation is more efficient in vitro than in living cells. Polysumoylation occurs on several substrates in vitro. 2) SUMO isopeptidases have little substrate specificity. 3) The SUMO ligases, PIAS1 and PIASxβ, have broader substrate specificities than does PIASy. 4) Although SUMO1 and SUMO2 are equally efficiently conjugated to a given substrate in vitro, SUMO1 conjugation is more efficient in vivo. 5) Most SUMO substrates localize to the nucleus, and sumoylation does not generally affect their subcellular localization. Therefore, sumoylation appears to regulate the functions of its substrates through multiple, context-dependent mechanisms.
AB - Small ubiquitin-like modifier (SUMO) regulates diverse cellular processes through its reversible, covalent attachment to target proteins. Many SUMO substrates are involved in transcription and chromatin structure. Sumoylation appears to regulate the functions of target proteins by changing their subcellular localization, increasing their stability, and/or mediating their binding to other proteins. Using an in vitro expression cloning approach, we have identified 40 human SUMO1 substrates. The spectrum of human SUMO1 substrates identified in our screen suggests general roles of sumoylation in transcription, chromosome structure, and RNA processing. We have validated the sumoylation of 24 substrates in living cells. Analysis of this panel of SUMO substrates leads to the following observations. 1) Sumoylation is more efficient in vitro than in living cells. Polysumoylation occurs on several substrates in vitro. 2) SUMO isopeptidases have little substrate specificity. 3) The SUMO ligases, PIAS1 and PIASxβ, have broader substrate specificities than does PIASy. 4) Although SUMO1 and SUMO2 are equally efficiently conjugated to a given substrate in vitro, SUMO1 conjugation is more efficient in vivo. 5) Most SUMO substrates localize to the nucleus, and sumoylation does not generally affect their subcellular localization. Therefore, sumoylation appears to regulate the functions of its substrates through multiple, context-dependent mechanisms.
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U2 - 10.1074/jbc.M411718200
DO - 10.1074/jbc.M411718200
M3 - Article
C2 - 15561718
AN - SCOPUS:14244249406
SN - 0021-9258
VL - 280
SP - 5004
EP - 5012
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 6
ER -