MCU Controlled JFET switch for negative voltage?
You could tag a voltage divider off an PNP like this







simulate this circuit &ndash; Schematic created using CircuitLab

Note Vcc shown above is expected to be 5V. If your logic output is at a lesser voltage you would need to recalculate R1 appropriately. 

Or if ground needs to really be ground, the circuit below may be better. Note the control signal inversion.







simulate this circuit

In both cases, you need to ensure Vhi of your output port is high enough to fully turn off the PNP transistor. If not, either use an open-collector output with a pull-up on the base, or drop the emitter voltage a little with a diode or two.