A New α-Amylase from Reticulitermes speratus KMT1

ABSTRACT Termites are wood pests that cause vast economic damage every year. They digest both cellulose and starch, but the enzymes for starch digestion have not been well characterized. We obtained complete amino acid sequence information on the KME1 α-amylase from Reticulitermes speratus KMT1 through analysis of total mRNA sequences. The KME1enzyme has two α-amylase domains and is 68% identical to the α-amylase from Blattellager manica, its closest rela-tive in the GenBank database. Some unique features of its conserved region and its distant evolutionary relationship toother insect α-amylases suggest that KME1 is a new type of α-amylase.Keywords : Termite, Reticulitermes speratus KMT1, α-amylase, Homologous search, Phylogenetic analysis 1. INTRODUCTION 1) Termites efficiently degrade woody cellulose through a symbiotic collaboration with gut mi-croorganisms, and they absorb the degradation products as nutrients (Nakashima et al., 2002; Watanabe et al., 1997; Zhou et al., 2007). In the first step of cellulose degradation, termites secrete an endo-β-1,4-glucanase from their sali-vary glands that enzymatically reduces the size of cellulose. Later, symbiotic microorganisms in the termite gut secrete cellobiohydrolase and β-glucosidase to convert cellulose into glucose (Cho et al., 2010; Nakashima et al., 2002). Since starch is an energy-storing material in biological systems, termites should be able to use it as food. It has been shown that Coptotermes for-mosanus can survive on starch or glucose as a sole nutrient as well as on cellulose, and it does this without the assistance of symbiotic protozoans (Kanai et al., 2008). However, only the sequence of a partial catalytic domain of the amylase gene from Coptotermes formosanus has so far been reported (GenBank Accession number: KC740998); no complete sequence is available. Amylases are classified into three groups, α- amylase (EC 3.2.1.1), β-amylase (EC 3.2.1.2), and γ-amylase (EC 3.2.1.3), depending on where they cleave the α(1 → 4) glucosidic linkage on