title: Crystal structure and characterization of a novel L-serine ammonia-lyase from Rhizomucor miehei.
abstract: L-serine ammonia-lyase, as a member of the β-family of pyridoxal-5'-phosphate (PLP) dependent enzymes, catalyzes the conversion of L-serine (L-threonine) to pyruvate (α-ketobutyrate) and ammonia. The crystal structure of L-serine ammonia-lyase from Rhizomucor miehei (RmSDH) was solved at 1.76 Å resolution by X-ray diffraction method. The overall structure of RmSDH had the characteristic β-family PLP dependent enzyme fold. It consisted of two distinct domains, both of which show the typical open twisted α/β structure. A PLP cofactor was located in the crevice between the two domains, which was attached to Lys52 by a Schiff-base linkage. Unique residue substitutions (Gly78, Pro79, Ser146, Ser147 and Thr312) were discovered at the catalytic site of RmSDH by comparison of structures of RmSDH and other reported eukaryotic L-serine ammonia-lyases. Optimal pH and temperature of the purified RmSDH were 7.5 and 40 °C, respectively. It was stable in the pH range of 7.0-9.0 and at temperatures below 40 °C. This is the first crystal structure of a fungal L-serine ammonia-lyase. It will be useful to study the catalytic mechanism of β-elimination enzymes and will provide a basis for further enzyme engineering.
authors.affiliation: College of Food Science and Nutritional Engineering, Beijing Advanced Innovation Center of Food Nutrition and Human Health, China Agricultural University, Beijing 100083, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Qin
authors.affiliation: College of Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Ma
authors.affiliation: College of Food Science and Nutritional Engineering, Beijing Advanced Innovation Center of Food Nutrition and Human Health, China Agricultural University, Beijing 100083, China. Electronic address: zhqjiang@cau.edu.cn.
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012695:L-Serine Dehydratase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020103:Rhizomucor / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein
chemical_list: D005656:Fungal Proteins; D011994:Recombinant Proteins; D011732:Pyridoxal Phosphate; D012695:L-Serine Dehydratase
keywords: Crystal structure; Pyridoxal-5′-phosphate; Rhizomucor miehei; Serine dehydratase; l-Serine ammonia-lyase; β-Elimination enzymes