Maderbocus Riyaz, Fields Blanche L, Hamilton Keith, Luo Shukun, Tran Timothy H, Dietrich Lars E P, Tong Liang
Department of Biological Sciences, Columbia University, New York, NY, 10027, USA.
Nat Commun. 2017 Jul 31;8(1):160. doi: 10.1038/s41467-017-00233-z.
Pseudomonas species and other aerobic bacteria have a biotin-independent malonate decarboxylase that is crucial for their utilization of malonate as the sole carbon and energy source. The malonate decarboxylase holoenzyme contains four subunits, having an acyl-carrier protein (MdcC subunit) with a distinct prosthetic group, as well as decarboxylase (MdcD-MdcE) and acyl-carrier protein transferase (MdcA) catalytic activities. Here we report the crystal structure of a Pseudomonas malonate decarboxylase hetero-tetramer, as well as biochemical and functional studies based on the structural information. We observe a malonate molecule in the active site of MdcA and we also determine the structure of malonate decarboxylase with CoA in the active site of MdcD-MdcE. Both structures provide molecular insights into malonate decarboxylase catalysis. Mutations in the hetero-tetramer interface can abolish holoenzyme formation. Mutations in the hetero-tetramer interface and the active sites can abolish Pseudomonas aeruginosa growth in a defined medium with malonate as the sole carbon source.Some aerobic bacteria contain a biotin-independent malonate decarboxylase (MDC), which allows them to use malonate as the sole carbon source. Here, the authors present the crystal structure of a Pseudomonas MDC and give insights into its catalytic mechanism and function.
假单胞菌属细菌及其他需氧菌具有一种不依赖生物素的丙二酸脱羧酶，该酶对于它们将丙二酸作为唯一碳源和能源的利用至关重要。丙二酸脱羧酶全酶包含四个亚基，有一个带有独特辅基的酰基载体蛋白（MdcC亚基），以及脱羧酶（MdcD - MdcE）和酰基载体蛋白转移酶（MdcA）的催化活性。在此，我们报告了假单胞菌丙二酸脱羧酶异源四聚体的晶体结构，以及基于该结构信息的生化和功能研究。我们在MdcA的活性位点观察到一个丙二酸分子，并且还确定了在MdcD - MdcE活性位点含有辅酶A的丙二酸脱羧酶的结构。这两种结构都为丙二酸脱羧酶的催化作用提供了分子层面的见解。异源四聚体界面的突变可消除全酶的形成。异源四聚体界面和活性位点的突变可消除铜绿假单胞菌在以丙二酸作为唯一碳源的限定培养基中的生长。一些需氧菌含有一种不依赖生物素的丙二酸脱羧酶（MDC），这使它们能够利用丙二酸作为唯一碳源。在此，作者展示了假单胞菌MDC的晶体结构，并深入探讨了其催化机制和功能。
