1B5O

THERMUS THERMOPHILUS ASPARTATE AMINOTRANSFERASE SINGLE MUTANT 1

Summary for 1B5O

• Entry DOI: 10.2210/pdb1b5o/pdb
• Descriptor: PROTEIN (ASPARTATE AMINOTRANSFERASE), PHOSPHATE ION, PYRIDOXAL-5'-PHOSPHATE, ... (4 entities in total)
• Functional Keywords: aminotransferase, pyridoxal enzyme, transferase
• Biological source: Thermus thermophilus
• Cellular location: Cytoplasm (By similarity): Q56232
• Total number of polymer chains: 2
• Total formula weight: 84805.89

Authors

Ura, H.,Nakai, T.,Kawaguchi, S.I.,Miyahara, I.,Hirotsu, K.,Kuramitsu, S. (deposition date: 1999-01-07, release date: 2003-09-02, Last modification date: 2023-08-09)

Primary citation

Ura, H.,Nakai, T.,Kawaguchi, S.I.,Miyahara, I.,Hirotsu, K.,Kuramitsu, S.
Substrate recognition mechanism of thermophilic dual-substrate enzyme
J.BIOCHEM.(TOKYO), 130:89-98, 2001

PubMed Abstract: Aspartate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus HB8 (ttAspAT), has been believed to be specific for an acidic substrate. However, stepwise introduction of mutations in the active-site residues finally changed its substrate specificity to that of a dual-substrate enzyme. The final mutant, [S15D, T17V, K109S, S292R] ttAspAT, is active toward both acidic and hydrophobic substrates. During the course of stepwise mutation, the activities toward acidic and hydrophobic substrates changed independently. The introduction of a mobile Arg292* residue into ttAspAT was the key step in the change to a "dual-substrate" enzyme. The substrate recognition mechanism of this thermostable "dual-substrate" enzyme was confirmed by X-ray crystallography. This work together with previous studies on various enzymes suggest that this unique "dual-substrate recognition" mechanism is a feature of not only aminotransferases but also other enzymes.

PubMed: 11432784

Experimental method

X-RAY DIFFRACTION (2.2 Å)