SanM通过与SanN相互作用，在尼可霉素生物合成中催化4-吡啶基-2-氧代-4-羟基异戊酸酯的形成。
SanM catalyzes the formation of 4-pyridyl-2-oxo-4-hydroxyisovalerate in nikkomycin biosynthesis by interacting with SanN.
作者信息
Ling Hongbo, Wang Guojun, Tian Yuqing, Liu Gang, Tan Huarong
机构信息
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
出版信息
Biochem Biophys Res Commun. 2007 Sep 14;361(1):196-201. doi: 10.1016/j.bbrc.2007.07.016. Epub 2007 Jul 16.
Nikkomycins are peptidyl nucleoside antibiotics with potent activities against phytopathogenic and human pathogenic fungi. The sanM and sanN genes are required for the nikkomycin biosynthesis of Streptomyces ansochromogenes. In the present study, interaction between SanM and SanN was identified by yeast two-hybrid and co-immunoprecipitation assays. Moreover, SanM and SanN were heterologously expressed and purified. Further biochemical assay demonstrated that the SanM-SanN interaction is essential for SanM aldolase activity but not for SanN dehydrogenase activity. SanM converts piconaldehyde and 2-oxobutyrate to 4-pyridyl-2-oxo-4-hydroxyisovalerate in nikkomycin biosynthesis by interacting with SanN. Steady state kinetics analysis revealed that K(m) and k(cat)/K(m) of SanM are 123.2 microM and 11.4 mM(-1)s(-1) for picolinaldehyde, while 335.6 microM and 4.0 mM(-1)s(-1) for 2-oxobutyrate, respectively. However, SanN as a dehydrogenase is independent of SanM.
多氧霉素是一类肽基核苷类抗生素，对植物病原真菌和人类病原真菌具有强大的活性。产色链霉菌的多氧霉素生物合成需要sanM和sanN基因。在本研究中，通过酵母双杂交和免疫共沉淀试验鉴定了SanM和SanN之间的相互作用。此外，还对SanM和SanN进行了异源表达和纯化。进一步的生化分析表明，SanM与SanN的相互作用对SanM醛缩酶活性至关重要，但对SanN脱氢酶活性并非如此。在多氧霉素生物合成过程中，SanM通过与SanN相互作用，将吡啶甲醛和2-氧代丁酸转化为4-吡啶基-2-氧代-4-羟基异戊酸。稳态动力学分析表明，SanM对吡啶甲醛的K(m)和k(cat)/K(m)分别为123.2 μM和11.4 mM⁻¹s⁻¹，对2-氧代丁酸的K(m)和k(cat)/K(m)分别为335.6 μM和4.0 mM⁻¹s⁻¹但是，作为脱氢酶 的SanN不依赖于SanM。
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