Structural basis and specificity of human otubain 1 mediated deubiquitylation

Mariola J Edelmann , Alexander Iphoefer , Masato Akutsu , Mikael Altun , Katalin Di Gleria , Holger B. Kramer , Edda Fiebiger , Sirano Dhe-Paganon , Benedikt M Kessler (1)

1 Clinical Medicine

Otubain 1 (OTUB1) is a human deubiquitylating enzyme implicated in mediating lymphocyte antigen responsiveness, but whose molecular function is generally not well defined. A structural analysis of OTUB1 shows differences in accessibility to the active site and in surface properties of the substrate binding regions when compared with its close homologue, otubain 2 (OTUB2), suggesting variations in regulatory mechanisms and substrate specificity. Biochemical analysis reveals that OTUB1 has a preference for cleaving lys48- over lys63-linked poly-ubiquitin chains, and it is capable of cleaving NEDD8, but not SUMO1/2/3 and ISG15 conjugates. A functional comparison of OTUB1 and OTUB2 indicated a differential reactivity towards ubiquitin based active-site probes carrying a vinyl-methylester, a 2-chloroethyl, or a 2-bromoethyl group at the C-terminus. Mutational analysis suggested that a narrow P1' site as observed in OTUB1 correlates with its ability to preferentially cleave lys48- linked ubiquitin chains. Analysis of cellular interaction partners of OTUB1 by co-immunoprecipitation and tandem mass spectrometry experiments demonstrated that FUS (also known as TLS or CHOP) and Rack1 (also known as GNB2L1) are part of OTUB1 containing complexes, pointing towards a molecular function of this deubiquitylating enzyme in RNA processing and cell adhesion/morphology.

Mots clés: Life Sciences

Mariola J Edelmann, Alexander Iphoefer, Masato Akutsu, Mikael Altun, Katalin Di Gleria, et al.. Structural basis and specificity of human otubain 1 mediated deubiquitylation. Biochemical Journal, 2009, 418 (2), pp.379-390. ⟨10.1042/BJ20081318⟩. ⟨hal-00479060⟩