Methanol, as an alternative biorefinery feedstock, has the following advantages: 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, researchers from Laboratory of Systems & Synthetic Biotechnology led by Prof. ZHENG Ping and Systems Biology Center led by Prof. SUN Jibin at Tianjin Institute of Industrial Biotechnology (TIB), Chinese Academy of Sciences rationally 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 first 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% improvement in F6P formation efficiency.Furthermore, dynamic light scattering and transmission electron microscope analyses suggested that fusion engineering brought changes in polymerization states of proteins, which may consequently affect the catalytic characteristics. This study demonstrates that fusion engineering is a promising strategy for solving formaldehyde toxicity and enhancing methanol bioconversion rate.
Fusion engineering strategy for enhancing methanol bioconversion to F6P （Image by TIB）
Contact: Prof. ZHENG Ping
Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences.
32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
Tel: 022-84861997/84861977 Fax: 022-84861926 E-mail: tib_zh(AT)tib.cas.cn
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