4.6 Article

Semi-Rational Design of Proteus mirabilis l-Amino Acid Deaminase for Expanding Its Substrate Specificity in α-Keto Acid Synthesis from l-Amino Acids

期刊

CATALYSTS
卷 12, 期 2, 页码 -

出版社

MDPI
DOI: 10.3390/catal12020175

关键词

l-amino deaminase; amino acids; keto acids; substrate spectrum; substrate channel

资金

  1. National Key R&D Program of China [2021YFC2102000]
  2. National Natural Science Foundation of China [22178147, 31872891]
  3. Program of Introducing Talents of Discipline to Universities [111-2-06]
  4. High-End Foreign Experts Recruitment Program [G2021144005L]
  5. Program for Advanced Talents within Six Industries of Jiangsu Province [2015-NY-007]
  6. National Program for Support of Top-notch Young Professionals
  7. Priority Academic Program Development of Jiangsu Higher Education Institutions
  8. Top-notch Academic Programs Project of Jiangsu Higher Education Institutions
  9. Jiangsu province Collaborative Innovation Center for Advanced Industrial Fermentation industry development program
  10. National First-Class Discipline Program of Light Industry Technology and Engineering [LITE2018-09]

向作者/读者索取更多资源

In this study, the substrate specificity of a l-amino acid deaminase (LAAD) from Proteus mirabilis (PmiLAAD) was broadened using a semi-rational design strategy. Mutation of the key residue E417 expanded the substrate channel and improved the catalytic activity of PmiLAAD towards bulky and basic l-amino acid substrates. The variant PmiLAAD(E417K) showed remarkable catalytic activity improvement on multiple substrates.
l-amino acid deaminases (LAADs) are flavoenzymes that catalyze the stereospecific oxidative deamination of l-amino acids into alpha-keto acids, which are widely used in the pharmaceutical, food, chemical, and cosmetic industries. However, the substrate specificity of available LAADs is limited, and most substrates are concentrated on several bulky or basic l-amino acids. In this study, we employed a LAAD from Proteus mirabilis (PmiLAAD) and broadened its substrate specificity using a semi-rational design strategy. Molecular docking and alanine scanning identified F96, Q278, and E417 as key residues around the substrate-binding pocket of PmiLAAD. Site-directed saturation mutagenesis identified E417 as the key site for substrate specificity expansion. Expansion of the substrate channel with mutations of E417 (E417L, E417A) improved activity toward the bulky substrate l-Trp, and mutation of E417 to basic amino acids (E417K, E417H, E417R) enhanced the universal activity toward various l-amino acid substrates. The variant PmiLAAD(E417K) showed remarkable catalytic activity improvement on seven substrates (l-Ala, l-Asp, l-Ile, l-Leu, l-Phe, l-Trp, and l-Val). The catalytic efficiency improvement obtained by E417 mutation may be attributed to the expansion of the entrance channel and its electrostatic interactions. These PmiLAAD variants with a broadened substrate spectrum can extend the application potential of LAADs.

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