Monoubiquitylation in the Fanconi anemia DNA damage response pathway

The hereditary genetic disorder Fanconi anemia (FA) belongs to the heterogeneous group of diseases associated with defective DNA damage repair. Recently, several reviews have discussed the FA pathway and its molecular players in the context of genome maintenance and tumor suppression mechanisms [H. Joenje, K.J. Patel, The emerging genetic and molecular basis of Fanconi anaemia, Nat. Rev. Genet. 2 (2001) 446-457; W. Wang, Emergence of a DNA-damage response network consisting of Fanconi anaemia and BRCA proteins, Nat. Rev. Genet. 8 (2007) 735-748; L.J. Niedernhofer, A.S. Lalai, J.H. Hoeijmakers, Fanconi anemia (cross)linked to DNA repair, Cell 123 (2005) 1191-1198; K.J. Patel, Fanconi anemia and breast cancer susceptibility, Nat. Genet. 39 (2007) 142-143]. This review assesses the influence of post-translational modification by ubiquitin. We review and extract the key features of the enzymatic cascade required for the monoubiquitylation of the FANCD2/FANCI complex and attempt to include recent findings into a coherent mechanism. As this part of the FA pathway is still far from fully understood, we raise several points that must be addressed in future studies.