Abstract：
Lactiplantibacillus plantarum is one of the important species of lactic acid bacterium (LAB) found in diverse environments, with many strains exhibiting probiotic properties. In our previous study, 41.6% of protein families (PFs) encoded by 395 plasmids from several L. plantarum strains were found to be hypothetical proteins with no predicted function. This study aimed at predicting the functions of these 647 hypothetical proteins using 21 different bioinformatics methods. As a result, 160 PFs could be newly annotated. A lower proportion of plasmid-specific functions was annotated as compared to the functions shared between plasmids and chromosomes. Also, hypothetical proteins were less conserved than the annotated proteins across L.plantarum plasmids. Based on the subcellular localization, cell envelope proteins represented the biggest category in the newly annotated proteins. Transporters (112 PFs) which was a part of cell envelop proteins represented the largest functional group. Additionally, 40 and 25 other PFs were predicted to contain signal peptides and transmembrane helices, respectively. We speculate that such hypothetical proteins might be involved in the transport of various chemicals and environmental interactions in L. plantarum. In the future, functional characterization of these proteins through wet-lab experimental approach can provide novel insights into their contribution to the physiology, probiotic properties, and industrial utility of these bacteria.
摘要：
植物乳杆菌是在不同环境中发现的乳酸菌（LAB）的重要物种之一。许多菌株表现出益生菌特性。在我们之前的研究中,发现来自几种植物乳杆菌菌株的395个质粒编码的蛋白质家族（PF）中有41.6％是假设的蛋白质，没有预测的功能。这项研究旨在使用21种不同的生物信息学方法预测这647种假设蛋白质的功能。因此,160个PF可以被新注释。与质粒和染色体之间共享的功能相比,注释了较低比例的质粒特异性功能。此外，在植物乳杆菌质粒中，假设的蛋白质比注释的蛋白质保守得少。基于亚细胞定位，细胞包膜蛋白代表了新注释蛋白质中最大的类别。作为细胞包膜蛋白的一部分的转运蛋白（112PF）代表了最大的官能团。此外,预测40和25个其他PF包含信号肽和跨膜螺旋，分别。我们推测，这些假设的蛋白质可能参与植物乳杆菌中各种化学物质的运输和环境相互作用。在未来,通过湿实验室实验方法对这些蛋白质的功能表征可以为它们对生理学的贡献提供新的见解，益生菌特性，和这些细菌的工业效用。
