First-quantized N=4 Yang-Mills
  We present simple first-class-constraint actions and BRST operators for the 4D N=4 superparticle. Each generation of ghosts has 2 super-indices, like the coordinates. The constraints that define projective superspace close in a super Yang-Mills background due to the presence of a (non-central) U(1) generator in the algebra. 
Machiko Hatsuda, Yu-tin Huang, and Warren Siegel