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Identification and characterization of Ufm1‐specific proteases, UfSP1 and UfSP2
Author(s) -
Kang Sung Hwan,
Seong Minu,
Ha Byung Hak,
Ovaa Huib,
Komatsu Masaaki,
Tanaka Keiji,
Bang Ok Sun,
Chung Chin Ha
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1020
Subject(s) - proteases , biochemistry , deubiquitinating enzyme , ubiquitin , serine , enzyme , amino acid , chemistry , proteolysis , peptide sequence , biology , gene
A new ubiquitin (Ub)‐like protein, Ufm1 (ubiquitin‐fold modifier 1), has recently been identified. It shares 16% identity in amino acid sequence with Ub, but has a strong similarity in its tertiary structure to Ub. Like Ub, Ufm1 is synthesized as precursors that have extensions of various amino acid sequences. Therefore, it needs to be processed to expose C‐terminal Gly prior to conjugation to target proteins. Here we report the purification, cloning, and characterization of two novel mouse Ufm1‐specific proteases, termed UfSP1 and UfSP2. UfSP1 and UfSP2 are consisted of 217 and 461 amino acids, respectively, and have no sequence homology with previously known proteases. UfSP2 is present in most multi‐cellular organisms including mammals, flies, nematodes, and plants, whereas UfSP1 cannot be found in plant and nematodes upon database search. UfSP1 and UfSP2 cleaved the C‐terminal extension of Ufm1 but not that of Ub or other Ub‐like proteins. Both proteases also could release Ufm1 from Ufm1‐conjugated cellular proteins. They were sensitive to inhibition by sulfhydryl‐blocking agents, such as N‐ethylmaleimide, and their active site Cys can be labeled with Ufm1‐vinylmethylester. Furthermore, replacement of the Cys residue by Ser led to a complete loss of the enzyme activities. These results indicate that UfSP1 and UfSP2 are novel thiol proteases that specifically process the C‐terminus of Ufm1.