从沼泽红假单胞菌中克隆具有生产 5-氨基乙酰丙酸有利特性的两种 5-氨基乙酰丙酸合酶同工酶 HemA 和 HemO。
Cloning of two 5-aminolevulinic acid synthase isozymes HemA and HemO from Rhodopseudomonas palustris with favorable characteristics for 5-aminolevulinic acid production.
机构信息
College of Biotechnology, Tianjin University of Science and Biotechnology, Tianjin 300457, People's Republic of China.
出版信息
Biotechnol Lett. 2013 May;35(5):763-8. doi: 10.1007/s10529-013-1143-4. Epub 2013 Jan 22.
5-Aminolevulinic acid (ALA) synthase (ALAS) HemA from non-sulfur photosynthetic bacteria has been used for the ALA bioproduction, whereas the isoenzyme HemT/HemO is less studied and not used for ALA production. Two ALAS-encoding genes, hemA and hemO from Rhodopseudomonas palustris were cloned, purified and characterized. The ALASs had very high specific activity, 3.6 and 2.7 U/mg, respectively, and strong affinity for one of its substrates, succinyl-CoA, K m with values of 11 and 4.4 μM, respectively. HemO retained up to 60 % maximum activity within a broad range of concentrations of hemin, while HemA kept only 20 % at 10 μM hemin. Escherichia coli overexpressing HemA or HemO produced 5.7 and 6.3 g ALA/l, respectively, in a 5 l bioreactor.
5-氨基乙酰丙酸（ALA）合酶（ALAS）来自非硫光合细菌的 HemA 已被用于 ALA 的生物生产，而同工酶 HemT/HemO 的研究较少，不用于 ALA 生产。本研究从沼泽红假单胞菌中克隆、纯化并表征了两个编码 ALAS 的基因 hemA 和 hemO。ALAS 具有非常高的比活性，分别为 3.6 和 2.7 U/mg，对其底物之一琥珀酰辅酶 A 的亲和力很强，K m 值分别为 11 和 4.4 μM。HemO 在广泛的血红素浓度范围内保留了高达 60%的最大活性，而 HemA 在 10 μM 血红素时仅保留了 20%。在 5L 生物反应器中，过量表达 HemA 或 HemO 的大肠杆菌分别产生了 5.7 和 6.3 g/L 的 ALA。
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