Chromohalobacter salexigens DSM 3043 can grow on N,N-dimethylglycine (DMG) as the sole C, N, and energy source and utilize sarcosine as the sole N source under aerobic conditions. However, little is known about the genes and enzymes involved in the conversion of DMG to sarcosine in this strain. In the present study, gene disruption and complementation assays indicated that the csal_0990, csal_0991, csal_0992, and csal_0993 genes are responsible for DMG degradation to sarcosine. The csal_0990 gene heterologously expressed in Escherichia coli was proven to encode an unusual DMG dehydrogenase (DMGDH). The enzyme, existing as a monomer of 79 kDa with a noncovalently bound flavin adenine dinucleotide, utilized both DMG and sarcosine as substrates and exhibited dual coenzyme specificity, preferring NAD⁺ to NADP⁺. The optimum pH and temperature of enzyme activity were determined to be 7.0 and 60°C, respectively. Kinetic parameters of the enzyme toward its substrates were determined accordingly. Under high-salinity conditions, the presence of DMG inhibited growth of the wild type and induced the production and accumulation of trehalose and glucosylglycerate intracellularly. Moreover, exogenous addition of DMG significantly improved the growth rates of the four DMG^– mutants (Δcsal_0990, Δcsal_0991, Δcsal_0992, and Δcsal_0993) incubated at 37°C in S-M63 synthetic medium with sarcosine as the sole N source. ¹³C nuclear magnetic resonance (¹³C-NMR) experiments revealed that not only ectoine, glutamate, and N-acetyl-2,4-diaminobutyrate but also glycine betaine (GB), DMG, sarcosine, trehalose, and glucosylglycerate are accumulated intracellularly in the four mutants.

中文翻译：

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N，N-二甲基甘氨酸的作用及其对肌氨酸的分解代谢在柳杉嗜盐菌DSM 3043中的作用。

salexigens DSM 3043嗜盐杆菌可在N，N-二甲基甘氨酸（DMG）上生长，作为唯一的C，N和能源，并在有氧条件下利用肌氨酸作为唯一的N源。然而，关于该菌株中DMG转化为肌氨酸的基因和酶知之甚少。在本研究中，基因破坏和互补分析表明csal_0990，csal_0991，csal_0992和csal_0993基因是DMG降解为肌氨酸的原因。在大肠杆菌中异源表达的csal_0990基因被证明编码不寻常的DMG脱氢酶（DMGDH）。的酶，现有79 kDa的单体与非共价结合的黄素腺嘌呤二核苷酸，所用既DMG和肌氨酸作为底物并表现出双特异性辅酶，宁愿NAD ⁺到NADP ⁺。酶活性的最佳pH和温度分别确定为7.0和60℃。相应地确定了酶朝向其底物的动力学参数。在高盐度条件下，DMG的存在抑制了野生型的生长，并在细胞内诱导了海藻糖和葡萄糖基甘油酸酯的产生和积累。此外，外源添加DMG可显着提高四个DMG ^–突变体（Δcsal_0990，Δcsal_0991，Δcsal_0992和Δcsal_0993）在37-C的S-M63合成培养基中以肌氨酸作为唯一N源孵育。¹³ C核磁共振（¹³ C-NMR）实验表明，不仅油桃素，谷氨酸和N-乙酰基2,4-二氨基丁酸，而且甘氨酸甜菜碱（GB），DMG，肌氨酸，海藻糖和葡萄糖基甘油酸酯都在细胞内积累四个突变体。