AFM_RawData_Succinyltransferase_Eskandarian

Preparation conditions and the technical setup for AFM experiments were conducted as per Eskandarian <i>et al</i>. 2017. Cells of <i>M. smegmatis</i>wildtype expressing Wag31-GFP were mixed with non-fluorescent <i>MSMEG_3187</i>and deposited on a PDMS-coated coverslip. WT cells were distinguished from <i>MSMEG_3187</i>cells by optical fluorescence microscopy. AFM measurements were made using a Dimension Icon scan head (Bruker) using ScanAsyst fluid cantilevers (Bruker) with a nominal spring constant of 0.7 N m^-1in Peak Force QNM mode at a force setpoint ~1 nN and typical scan rates of 0.3 Hz. Indentation on the cell surface was estimated to be ~10 nm with a range of ~5 nm in the Z-axis. Height, peak force error, and DMT modulus channels were recorded for all scanned images in the trace and retrace directions. Images were processed using Gwyddion (Department of Nanometrology, Czech Metrology Institute – http://gwyddion.net). ImageJ was used for extracting bacterial cell profiles from height and DMT modulus images in a tabular format. A two-sided Wilcoxon rank sum U test was used to analyze the data with a continuity correction and confidence level of 95% using MatLab.<br>

原子力显微镜（Atomic Force Microscopy, AFM）实验的制备条件与技术装置均参照Eskandarian等人2017年的研究开展。表达Wag31-GFP的耻垢分枝杆菌（Mycobacterium smegmatis, M. smegmatis）野生型细胞，与非荧光性的MSMEG_3187菌株细胞混合后，沉积于聚二甲基硅氧烷（Polydimethylsiloxane, PDMS）包被的盖玻片上。通过光学荧光显微镜可区分野生型细胞与MSMEG_3187菌株细胞。AFM测量采用布鲁克（Bruker）公司的Dimension Icon扫描头，搭配ScanAsyst流体悬臂（Bruker），其标称弹簧常数为0.7 N·m⁻¹，以峰值力定量纳米力学成像（Peak Force QNM）模式运行，力设定值约为1 nN，典型扫描速率为0.3 Hz。细胞表面的压入深度估算为约10 nm，Z轴方向压入范围约5 nm。所有扫描图像的正向（trace）与反向（retrace）通道均记录了高度、峰值力误差以及Derjaguin-Müller-Toporov（DMT）模量信号。图像采用Gwyddion（捷克计量学院纳米计量系，http://gwyddion.net）进行后期处理。使用ImageJ从高度图像与DMT模量图像中以表格形式提取细菌细胞轮廓。数据分析采用双侧Wilcoxon秩和U检验，辅以连续性校正，置信水平设定为95%，相关计算通过MatLab完成。