There doesn't seem to be a default keyboard shortcut for this, but you could easily define one yourself. The commands for rotating the screen are:

xrandr --rotate left

xrandr --rotate normal

xrandr --rotate right

You should be able to define your own shortcuts in the "Keyboard" application (Shortcuts tab), as explained here: How can I rotate my display in the most easy way?. If this works for you, that's great! However, I wasn't able to make it work this way.

As an alternative, you may want to delete the functions that are assigned to the keyboard combinations originally (they should be in the "Windows" section of the previous tab). After that, install a small program called "xbindkeys" to assign these keys.

sudo apt-get install xbindkeys

Create a configuration file:

gedit .xbindkeysrc

and enter this inside the config file

"xrandr --rotate left"

Control+Alt + Left

"xrandr --rotate right"

Control+Alt + Right

"xrandr --rotate normal"

Control+Alt + Up

Hope this works out for you. You can find more info on xbindkeys online!