Simanshu Dhirendra K, Chittori Sagar, Savithri H S, Murthy M R N
Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
J Biosci. 2007 Sep;32(6):1195-206. doi: 10.1007/s12038-007-0121-1.
In Escherichia coli and Salmonella typhimurium, L-threonine is cleaved non-oxidatively to propionate via 2-ketobutyrate by biodegradative threonine deaminase, 2-ketobutyrate formate-lyase (or pyruvate formate-lyase), phosphotransacetylase and propionate kinase. In the anaerobic condition, L-threonine is converted to the energy-rich keto acid and this is subsequently catabolised to produce ATP via substrate-level phosphorylation, providing a source of energy to the cells. Most of the enzymes involved in the degradation of L-threonine to propionate are encoded by the anaerobically regulated tdc operon. In the recent past, extensive structural and biochemical studies have been carried out on these enzymes by various groups. Besides detailed structural and functional insights, these studies have also shown the similarities and differences between the other related enzymes present in the metabolic network. In this paper, we review the structural and biochemical studies carried out on these enzymes.
在大肠杆菌和鼠伤寒沙门氏菌中，生物降解性苏氨酸脱氨酶、2-酮丁酸甲酸裂解酶（或丙酮酸甲酸裂解酶）、磷酸转乙酰酶和丙酸激酶可通过2-酮丁酸将L-苏氨酸非氧化裂解为丙酸。在厌氧条件下，L-苏氨酸被转化为富含能量的酮酸，随后通过底物水平磷酸化将其分解代谢以产生ATP，为细胞提供能量来源。参与L-苏氨酸降解为丙酸的大多数酶由厌氧调节的tdc操纵子编码。最近，不同的研究小组对这些酶进行了广泛的结构和生化研究。除了详细的结构和功能见解外，这些研究还揭示了代谢网络中其他相关酶之间的异同。在本文中，我们综述了对这些酶进行的结构和生化研究。
