FIGURE 4.

Machine learning classifies invertebrate PAPS synthases as PAPSS2 types. A, a support vector machine and a random forest were trained to discriminate between PAPSS1- and -S2-type sequences using 45 PAPSS1 and 47 PAPSS2 sequences from vertebrates. The predicted classes for six invertebrate sequences including C. elegans PPS-1 are shown for the random forest output. All these proteins are clearly classified as PAPSS2-type by both machine learning approaches. B, the CD spectrum of C. elegans PPS-1 resembles the one from human PAPSS2 including increased negative ellipticity at 208 nm. C, the thermal unfolding transition of C. elegans PPS-1 is shown. It is very similar to the one of human PAPSS2.