Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Division of Medical Biotechnologies and Preventive Medicine, University of Messina, 98125 Messina, Italy.
Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98125 Messina, Italy.
Molecules. 2021 Nov 22;26(22):7045. doi: 10.3390/molecules26227045.
Trimethylaminuria (TMAU) is a rare genetic disease characterized by the accumulation of trimethylamine (TMA) and its subsequent excretion trough main body fluids, determining the characteristic fish odour in affected patients. We realized an experimental study to investigate the role of several coding variants in the causative gene , that were only considered as polymorphic or benign, even if the available literature on them did not functionally explain their ineffectiveness on the encoded enzyme.
Mutational analysis of 26 TMAU patients was realized by Sanger sequencing. Detected variants were, subsequently, deeply statistically and in silico characterized to determine their possible effects on the enzyme activity. To achieve this goal, a docking prediction for TMA/FMO3 and an unbinding pathway study were performed. Finally, a TMAO/TMA urine quantification by 1H-NMR spectroscopy was performed to support modelling results.
The screening of all patients highlighted the presence of 17 variants distributed in 26 different haplotypes. Both non-sense and missense considered variants might impair the enzymatic kinetics of , probably reducing the interaction time between the protein catalytic site and TMA, or losing the wild-type binding site.
Even if further functional assays will confirm our predictive results, considering the possible role of variants with still uncertain effects, might be a relevant step towards the detection of novel scenarios in TMAU etiopathogenesis.
三甲基胺尿症（TMAU）是一种罕见的遗传性疾病，其特征是三甲胺（TMA）的积累及其随后通过主要体液排泄，导致受影响患者出现特征性的鱼腥味。我们进行了一项实验研究，旨在调查导致该疾病的基因中的几个编码变异体的作用，这些变异体仅被认为是多态性或良性的，即使现有文献并未从功能上解释它们对编码酶的无效性。
通过 Sanger 测序对 26 名 TMAU 患者进行突变分析。随后，对检测到的变异体进行深入的统计和计算机分析，以确定它们对酶活性的可能影响。为实现这一目标，进行了 TMA/FMO3 的对接预测和非结合途径研究。最后，通过 1H-NMR 光谱法对 TMAO/TMA 进行尿液定量，以支持建模结果。
对所有患者的筛选突出了存在分布在 26 个不同单倍型中的 17 个变异体。无意义和错义变异体都可能损害的酶动力学，可能会缩短蛋白质催化位点与 TMA 之间的相互作用时间，或失去野生型结合位点。
即使进一步的功能测定将证实我们的预测结果，考虑到具有不确定作用的变异体的可能作用，也可能是在 TMAU 发病机制中发现新情况的一个重要步骤。
