PMID:23396915

Citation	Choi, KH, Hwang, S and Cha, J (2013) Identification and characterization of MalA in the maltose/maltodextrin operon of Sulfolobus acidocaldarius DSM639. J. Bacteriol. 195:1789-99
Abstract	A putative maltose/maltodextrin operon was found in the Sulfolobus acidocaldarius DSM639 genome. The gene cluster consisted of 7 genes (malA, trmB, amyA, malG, malF, malE, and malK). Here, we report the identification of MalA, which is responsible for the hydrolysis of maltose or maltodextrin to glucose in S. acidocaldarius. The transcription level of malA was increased 3-fold upon the addition of maltose or starch to the medium. Moreover, the α-glucosidase activity for maltose as a substrate in cell extracts of S. acidocaldarius DSM639 was also 11- and 10-fold higher during growth in YT medium (Brock's mineral salts, 0.1% [wt/vol] tryptone, and 0.005% [wt/vol] yeast extract) containing maltose or starch, respectively, than during growth on other sugars. The gene encoding MalA was cloned and expressed in S. acidocaldarius. The enzyme purified from the organism was a dodecamer in its active state and showed strong maltose-hydrolyzing activity at 100°C and pH 5.0. MalA was remarkably thermostable, with half-lives of 33.8 h, 10.6 h, and 1.8 h at 95°C, 100°C, and 105°C, respectively. Substrate specificity and kinetic studies of MalA with maltooligosaccharides indicated that MalA efficiently hydrolyzed maltose to maltopentaose, which is a typical characteristic of GH31-type α-glucosidases. However, glycogen or starch was not hydrolyzed. Reverse transcription-PCR, sugar uptake, and growth studies of the wild-type DSM639 and ΔmalEFG mutant on different sugars demonstrated that MalA located in the mal operon gene cluster is involved in maltose and starch metabolism in S. acidocaldarius.
Links	PubMed PMC3624569 Online version:10.1128/JB.01713-12
Keywords	Archaeal Proteins/genetics; Archaeal Proteins/metabolism; Gene Expression Regulation, Archaeal/physiology; Gene Expression Regulation, Enzymologic/physiology; Kinetics; Maltose/metabolism; Multigene Family; Operon/physiology; Plasmids; Polysaccharides/metabolism; RNA, Archaeal/genetics; RNA, Archaeal/metabolism; Starch/metabolism; Substrate Specificity; Sulfolobus acidocaldarius/enzymology; Sulfolobus acidocaldarius/genetics; Sulfolobus acidocaldarius/metabolism; Transformation, Genetic; alpha-Glucosidases/genetics; alpha-Glucosidases/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
SULAC:Q4J9M3		GO:0032450: maltose alpha-glucosidase activity	ECO:0000314:		F		Figure 2 shows specific activity of MalA with various substrates	complete CACAO 8933
SULAC:Q4J9M3	enables	GO:0032450: maltose alpha-glucosidase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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