cDNA synthesis, Illumina MiSeq sequencing, processing of data, and peptide artificial synthesis. (A) The sequence of cDNA encoding OA-GL12. The precursor of OA-GL12 was composed of 58 animo acid residues and encoded by an mRNA composed of 326 bp. The mature sequence of OA-GL12 was assumed as ‘GLLSGINAEWPC’, which is shown in underline and italics. (B) The sequence alignments between OA-GL12 and Nigrocin-2S. Precursors of OA-GL12 and Nigrocin-2S shared sequence similarity, but no obvious similarity on mature peptides was observed. Meanwhile, differing from OA-GLA12, Nigrocin-2S was composed of an intramolecular disulphide bond located at C-terminus. The overall structures of these peptides shared highly conserved motif, which are divided into four parts: signal peptide, acidic segment, enzyme cleavage site, and the highly variable mature peptide.