Kleine Henning, Poreba Elzbieta, Lesniewicz Krzysztof, Hassa Paul O, Hottiger Michael O, Litchfield David W, Shilton Brian H, Lüscher Bernhard
Institut für Biochemie und Molekularbiologie, Klinikum, RWTH Aachen University, 52057 Aachen, Germany.
Mol Cell. 2008 Oct 10;32(1):57-69. doi: 10.1016/j.molcel.2008.08.009.
ADP-ribosylation controls many processes, including transcription, DNA repair, and bacterial toxicity. ADP-ribosyltransferases and poly-ADP-ribose polymerases (PARPs) catalyze mono- and poly-ADP-ribosylation, respectively, and depend on a highly conserved glutamate residue in the active center for catalysis. However, there is an apparent absence of this glutamate for the recently described PARP6-PARP16, raising questions about how these enzymes function. We find that PARP10, in contrast to PARP1, lacks the catalytic glutamate and has transferase rather than polymerase activity. Despite this fundamental difference, PARP10 also modifies acidic residues. Consequently, we propose an alternative catalytic mechanism for PARP10 compared to PARP1 in which the acidic target residue of the substrate functionally substitutes for the catalytic glutamate by using substrate-assisted catalysis to transfer ADP-ribose. This mechanism explains why the novel PARPs are unable to function as polymerases. This discovery will help to illuminate the different biological functions of mono- versus poly-ADP-ribosylation in cells.
ADP核糖基化控制着许多过程，包括转录、DNA修复和细菌毒性。ADP核糖基转移酶和聚ADP核糖聚合酶（PARP）分别催化单ADP核糖基化和聚ADP核糖基化，并且在催化过程中依赖于活性中心一个高度保守的谷氨酸残基。然而，最近描述的PARP6 - PARP16明显没有这个谷氨酸，这就引发了关于这些酶如何发挥作用的问题。我们发现，与PARP1不同，PARP10缺乏催化性谷氨酸，具有转移酶而非聚合酶活性。尽管存在这一根本差异，PARP10也能修饰酸性残基。因此，我们提出了一种与PARP1相比PARP10的替代催化机制，其中底物的酸性靶残基通过利用底物辅助催化来转移ADP核糖，在功能上替代了催化性谷氨酸。这种机制解释了为什么新型PARP不能作为聚合酶发挥作用。这一发现将有助于阐明细胞中单ADP核糖基化与聚ADP核糖基化不同的生物学功能。
