4GKL

Crystal structure of a noncanonic maltogenic alpha-amylase AmyB from Thermotoga neapolitana

Summary for 4GKL

• Entry DOI: 10.2210/pdb4gkl/pdb
• Descriptor: Alpha-amylase (2 entities in total)
• Functional Keywords: (alpha/beta)8 barrel, maltogenic alpha-amylase, hydrolase
• Biological source: Thermotoga neapolitana
• Total number of polymer chains: 2
• Total formula weight: 100226.98

Authors

Ha, N.C.,Jun, S.Y.,Kim, J.S. (deposition date: 2012-08-13, release date: 2013-02-27, Last modification date: 2024-03-20)

Primary citation

Jun, S.Y.,Kim, J.S.,Choi, K.H.,Cha, J.,Ha, N.C.
Structure of a novel alpha-amylase AmyB from Thermotoga neapolitana that produces maltose from the nonreducing end of polysaccharides
Acta Crystallogr.,Sect.D, 69:442-450, 2013

PubMed Abstract: An intracellular α-amylase, AmyB, has been cloned from the hyperthermophilic bacterium Thermotoga neapolitana. AmyB belongs to glycoside hydrolase family 13 and liberates maltose from diverse substrates, including starch, amylose, amylopectin and glycogen. The final product of AmyB is similar to that of typical maltogenic amylases, but AmyB cleaves maltose units from the nonreducing end, which is a unique property of this α-amylase. In this study, the crystal structure of AmyB from T. neapolitana has been determined at 2.4 Å resolution, revealing that the monomeric AmyB comprises domains A, B and C like other α-amylases, but with structural variations. In the structure, a wider active site and a putative extra sugar-binding site at the top of the active site were found. Subsequent biochemical results suggest that the extra sugar-binding site is suitable for recognizing the nonreducing end of the substrates, explaining the unique activity of this enzyme. These findings provide a structural basis for the ability of an α-amylase that has the common α-amylase structure to show a diverse substrate specificity.

PubMed: 23519419
DOI: 10.1107/S0907444912049219

Experimental method

X-RAY DIFFRACTION (2.4 Å)