Unglycosylated lysostaphin variant protein, nucleic acid molecule, vector and host cell, as well as a method for production of unglycosylated lysostaphin variant protein in a yeast expression system are provided. The proteins are produced in a Pichia pastoris expression system and have been shown to have activity equivalent to wild-type lysostaphin. The lysostaphin variant proteins can be used as therapeutic proteins for treatment of diseases such as Staphylococcus aureus infection.