These results were corroborated by bioinformatic HSP activation analysis of the polymyxin synthetase gene cluster in M-1, where the adenylation domains specified the amino acid substrates to be activated (Table 2). This is remarkable, since according to literature, these forms of polymyxin are rare and the fact that all three of the polymyxin gene clusters examined to date are from plant-associated this website strains of P. Table 2 Specificity-conferring amino acids and homologies of the adenylation domains in polymyxin synthetases of strains M-1, E681, and PKB1 Module/ strain Active site residues in A-domain Specified aa % aa E681 % aa PKB1 235 236 239 278 299 301 322 330 Module 1 pmxE1/M-1 D V G E
I S S I L-Dab 99 99 pmxE1/E681 D V G E I S S I L-Dab pmxE1/PKB1 D V W E I S S I L-Dab Module 2 pmxE2/M-1 D F W N I G M V L-Thr 99 98 pmxE2/E681 D F W N I G M V L-Thr pmxE2/PKB1 D F W N I G M V L-Thr Module 3 (W) pmxE3/M-1 D V G E I S S I D-Dab 98 92 pmxE3/E681 D V G E I S S I D-Dab pmxE3/PKB1 D V G E I S S I D-Dab Module 4 pmxE4/M-1 D V G Flavopiridol (Alvocidib) E I S A I L-Dab 96 96 pmxE4/E681 D V G E I S A I L-Dab pmxE4/PKB1 D V G E I S A I L-Dab Module 5 pmxE1/M-1 D V G E I S A I L-Dab
97 89 pmxE1/E681 D V G E I S A I L-Dab pmxE1/PKB1 D V G E I S A I L-Dab Module 6 (X) pmxA1/M-1 D A W T I A A I D-Phe 88 99 pmxA1/E681 D A W I V G A I D-Leu pmxA1/PKB1 D A W T I A A I D-Phe Module 7 (Y) pmxA2/M-1 D F W N I G M V L-Thr 99 51 pmxA2/E681 D F W N I G M V L-Thr pmxA2/PKB1 D G F L L G L V L-Leu Module 8 pmxA3/M-1 D V G E I S A I L-Dab 97 92 pmxA3/E681 D V G E I S A I L-Dab pmxA3/PKB1 D V G E I S A I L-Dab Module 9 pmxA4/M-1 D V G E I S A I L-Dab 96 91 pmxA4/E681 D V G E I S A I L-Dab pmxA4/PKB1 D V G E I S A I L-Dab Module 10 (Z) pmxB1/M-1 D F W N I G M V L-Thr 97 99 pmxB1/E681 D F W N I G M V L-Thr pmxB1/PKB1 D F W N I G M V L-Thr Modules 3 and 6 contained extra epimerization domains which might convert Dab3 and Phe6 to the D-configuration.