A pentagon can be partitioned into three triangles, so the sum of the degree measures of the angles of the pentagon is $$ v+w+x+y+z=540.$$The arithmetic sequence can be expressed as $ x-2d $, $ x-d $, $ x $, $ x+d $, and $ x+2d $, where $ d $ is the common difference, so $$ (x-2d)+(x-d)+x+(x+d)+(x+2d)=5x=540.$$Thus, $ x=\boxed{108} $.