Study of the Self-polymerization of SUMO1 and Characterization of the PolySUMO Chain Degradation Catalyzed by SENPs
Date Issued
2011
Date
2011
Author(s)
Chen, Nien-Ming
Abstract
The conjugation of SUMO moiety by SUMO conjugation system and the removal of the moiety by SENPs are important aspects of protein modification in cells. Analogous to ubiquitination, sumoylation regulates many physiological functions of proteins. It has been demonstrated that ubiquitin can form various polymeric chains via specific lysines to execute distinct functions. Although certain types of polymeric SUMO chains have been described, their roles in biological processes and the mechanism of formation remain unclear.
In this study, I transformed the enzymes required for sumoylation into Escherichia coli BL21 (DE3) to establish a sumoylation system, which lacks SENP-mediated desumoylation for analyzing the formation of polymeric SUMO chains. The results suggest that SUMO1, which has been considered unable to form polymers, is able to form polymeric chains mainly through self-conjugation at specific lysine residues nearby the flexible N terminus, indicating that the steric hindrance is a key factor modulating polySUMO chains formation. To investigate the character of polySUMO degradation catalyzed by SENPs, I examined the degradation of polySUMO chains by conducting the in vitro SENP activity analysis. The data showed that the catalytic domains of all SENPs, except SENP5, are able to deconjugate both polySUMO1 chains and polySUMO2 chains. Moreover, the catalytic core of SENP1 and SENP2 present similar preference toward polySUMO1 and polySUMO2 chains. I also found that the catalytic cores of SENP6 and SENP7 exhibit an exquisite substrate selectivity that polySUMO2 chains are deconjugated more efficiently than polySUMO1 chains.
Subjects
SUMO
SENPs
Polymeric chains
Type
thesis
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