Role of zinc finger domains of the transcription factor neuron-restrictivesilencer factor/repressor element-1 silencing transcription factor in DNA binding and nuclear localization

The transcription factor neuron-restrictive silencer factor/repressor eleme nt-1 (RE-1) silencing transcription factor (NRSF/REST) contains nine zinc f inger domains and binds to the DNA element, neuron-restrictive silencer ele ment/repressor element-1. REST4, a C-terminally truncated form of NRSF/REST , contains the five N-terminal zinc fingers and binds weakly to DNA yet is transported into the nucleus. To study the contribution of zinc fingers 6-8 to DNA binding, each was mutated. A mutation in zinc finger 6 or 8 had lit tle effect; however, mutation of zinc finger 7 diminished DNA binding. Muta tions in any two of these zinc fingers eliminated DNA binding. The contribu tion of zinc fingers 2-5 to nuclear targeting was studied. Deletion of zinc finger 5 prevented nuclear targeting. Mutations in zinc finger 2, 4, or 5 did not abolish nuclear targeting. However, a zinc finger 3 mutation togeth er with a zinc finger 2 mutation localized to the nuclear envelope. A zinc finger 3 mutation alone or in combination with a zinc finger 4 or 5 mutatio n produced a punctate nuclear distribution. These results suggest the prese nce of signals for nuclear targeting, for nuclear entry, and for release fr om the translocation machinery within zinc fingers 2-5 of REST 4.