Fungal α-amylases from three GH13 subfamilies: their sequence-structural features and evolutionary relationships

Abstract

This work delivers in silico analysis of α-amylases of fungal origin from three subfamilies of the α-amylase family GH13. Originally, typical fungal extracellular α-amylases were classified in the subfamily GH13_1, whereas later some intracellular α-amylases from fungi have been placed in GH13_5, which initially covered bacterial liquefying α-amylases. Recently, fungal α-amylases were identified as members of rather actinobacterial subfamily GH13_32. The main goal of the present study was to perform a detailed bioinformatics analysis of fungal α-amylases that exist in three sequence-different subfamilies. In addition, the study was undertaken in an effort to contribute to correct annotation of hypothetical proteins from genome sequencing projects and to identify new fungal α-amylases that could represent eventual intermediates among the subfamilies. Sequence logos made from their conserved sequence regions reflected that although each subfamily may exhibit its own unique sequence features, some positions are also shared by two subfamilies. With regard to evolutionary relationships, fungal α-amylases from subfamilies GH13_5 and GH13_32 seem to be evolutionarily more closely related to each other than to their counterparts from GH13_1. This relatedness was also seen in a more complex picture when taking into account the α-amylase homologues from other taxonomic groups and remaining GH13 α-amylase subfamilies.