Figure 1

Structure and expression pattern of genes containing the extraordinarily long amino-acid homopolymer. (a) Gene structure of the D. discoideum LSR1 (gene ID: DDB_G0271670) that includes 306 serine tandem repeats. The gray lines show the sequences of DNA, RNA and protein. The black bars mark the coding regions of DNA sequence, mRNA of the RNA sequence and tandem repeats of amino-acid serine. The feature of trinucleotide repeats in DNA sequence and ESTs coving RNA sequence are marked by thin gray bars. (b) Codon usage frequency. The x-axis marks the codon numbers. The y-axis marks the polyserines from Dictyostelids (DI=D. intermedium, DD=D. discoideum, PP=P. pallidum, PV=P. violaceum, DP=D. purpureum, DF=D. fasciculatum) and the codon diversity (numbers in parentheses). Bars with different fill effects show the frequency of each codon. (c) RNA-seq transcriptional profile. x-Axis marks the development stages (8–24 h) and the solitary stage (0 h). The y-axis marks the log RNA-seq read counts.