Biochem. J. (2005) 386
(325–330) (Printed in Great Britain)
Mapping residues of SUMO precursors essential in differential maturation by SUMO-specific protease, SENP1
Zheng XU and Shannon W. N. AU1
Department of Biochemistry, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong
SUMO (small ubiquitin-related modifier) is a member of the ubiquitin-like protein family that regulates cellular function of a variety of target proteins. SUMO proteins are expressed as their precursor forms. Cleavage of the residues after the ‘GG’ region of these precursors by SUMO-specific proteases in maturation is a prerequisite for subsequent sumoylation. To understand further this proteolytic processing, we expressed and purified SENP1 (sentrin-specific protease 1), one of the SUMO-specific proteases, using an Escherichia coli expression system. We show that SENP1 is capable of processing all SUMO-1, -2 and -3 in vitro; however, the proteolytic efficiency of SUMO-1 is the highest followed by SUMO-2 and -3. We demonstrate further that the catalytic domain of SENP1 (SENP1C) alone can determine the substrate specificity towards SUMO-1, -2 and -3. Replacement of the C-terminal fragments after the ‘GG’ region of SUMO-1 and -2 precursors with that of the SUMO-3, indicates that the C-terminal fragment is essential for efficient maturation. In mutagenesis analysis, we further map two residues immediately after the ‘GG’ region, which determine the differential maturation. Distinct patterns of tissue distribution of SENP1, SUMO-1, -2 and -3 are characterized. Taken together, we suggest that the observed differential maturation process has its physiological significance in the regulation of the sumoylation pathway.
Key words: maturation, sentrin-specific protease 1 (SENP1), small ubiquitin-related modifier (SUMO), SUMO-specific proteases, sumoylation, ubiquitin-like protein.
Abbreviations used: GST, glutathione S-transferase; SENP1, sentrin-specific protease 1; SUMO, small ubiquitin-related modifier; for brevity, the single-letter system for amino acids has been used, V94, for example means Val94.
1To whom correspondence should be addressed (email Shannon-au@cuhk.edu.hk).
Received 19 July 2004/4 October 2004; accepted 15 October 2004
Published as BJ Immediate Publication 18 October 2004, DOI 10.1042/BJ20041210
The Biochemical Society, London ©2005
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