tokens: Single amino acid substitutions were shown to result from the mutations pdr1 - 2 ( M308I ) , pdr1 - 3 ( F815S ) , pdr1 - 6 ( K302Q ) , pdr1 - 7 ( P298A ) and pdr1 - 8 ( L1036 W ) , whereas the intragenic suppressor mutant pdr1 - 100 is deleted for the two amino acids L537 and A538 .