Current methanol bioconversion holds promise for producing desired chemicals under economically viable operating conditions, however the efficiency is limited by unfavorable kinetics of methanol oxidation and assimilation. Fusion engineering strategy is used to enhance bioconversion
Methanol, as an alternative biorefinery feedstock, has advantages of abundant sources, low price, and high degree of reduction. Therefore, it is of great socio-economic significance to develop methanol-based biological manufacturing industry.
However, methanol bioconversion is limited by unfavorable kinetics of methanol oxidation and accumulation of highly toxic intermediate, formaldehyde.
Recently, a research group led by Prof. ZHENG Ping and Prof. SUN Jibin at the Tianjin Institute of Industrial Biotechnology (TIB) of the Chinese Academy of Sciences designed and constructed fusion proteins of ribulose monophosphate pathway enzymes. The fusion engineering strategy enhanced methanol bioconversion to fructose 6-phosphate (F6P), an important metabolic intermediate.
NAD-dependent methanol dehydrogenase (Mdh), 3-hexulose-6-phosphate synthase (Hps) and 6-phospho-3-hexuloisomerase (Phi) from different sources were evaluated for their catalytic activities. The candidates with the highest activity were then used to construct difunctional fusion proteins (Mdh-Hps and Hps-Phi) and trifunctional fusion proteins (Mdh-Hps-Phi) with flexible linkers.
Effects of linker length on the catalytic efficiency of fusion proteins were also investigated. The best fusion protein showed 4.8-fold improvement in methanol oxidation efficiency and 30 percent improvement in F6P formation efficiency.
Furthermore, dynamic light scattering and transmission electron microscope analyses suggested that fusion engineering brought changes in polymerisation states of proteins, which may consequently affect the catalytic characteristics.
Their study, published in ChemBioChem, demonstrates that fusion engineering is a promising strategy for solving formaldehyde toxicity and enhancing methanol bioconversion rate.
Source: Chinese Academy of Sciences
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