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Laboratory safety teams (LSTs), led by graduate student and postdoctoral researchers, have been propagating across the U.S. as a bottom-up approach to improving safety culture in academic research laboratories. Prior to the COVID-19 pandemic, LSTs relied heavily on in-person projects and events. Additionally, committed Champions from the ranks of safety professionals and faculty were critical to their operation and continued expansion. As was the case for many existing systems, the COVID-19 global crisis served as an operational stress test for LSTs, pushing them to unexpected new limits. The initial spread of COVID-19 brought with it a shutdown of academic institutions followed by a limited reopening that prohibited in-person gatherings and disrupted standard lines of communication upon which LSTs relied. Safety professionals and faculty members were required to take on new duties that were often undefined and time-consuming, substantially impacting their ability to support LSTs. In this case study, we report the impact of this operational stress test on 12 LSTs, detailing the adaptive means by which they survived and highlighting the key lessons learned by the represented LST leaders. The key takeaways were to spend time nurturing relationships with a diverse array of Champions, securing stable funding from multiple sources, and networking with members of LSTs from different institutions to strengthen moral support and broaden ideation for common challenges.

Miniprep Assisted Proteomics (MAP) is a rapid approach to bottom-up proteomics sample preparation by adventitious binding to Si-DNA minipreps. This combines the consistency of a commercially produced column with the low-cost of in-house devices.

N-terminal protein acetylation is a ubiquitous post-translational modification that broadly impacts diverse cellular processes in higher organisms. Bacterial proteins are also N-terminally acetylated, but the mechanisms and consequences of this modification in bacteria are poorly understood. We previously quantified widespread N-terminal protein acetylation in pathogenic mycobacteria (C. R. Thompson, M. M. Champion, and P.A. Champion, J Proteome Res 17(9): 3246-3258, 2018, https:// doi: 10.1021/acs.jproteome.8b00373). The major virulence factor EsxA (ESAT-6, Early secreted antigen, 6kDa) was one of the first N-terminally acetylated proteins identified in bacteria. EsxA is conserved in mycobacterial pathogens, including Mycobacterium tuberculosis and Mycobacterium marinum, a non-tubercular mycobacterial species that causes tuberculosis-like disease in ectotherms. However, enzyme responsible for EsxA N-terminal acetylation has been elusive. Here, we used genetics, molecular biology, and mass-spectroscopy based proteomics to demonstrate that MMAR_1839 (renamed Emp1, ESX-1 modifying protein, 1) is the putative N-acetyl transferase (NAT) solely responsible for EsxA acetylation in Mycobacterium marinum. We demonstrated that ERD_3144, the orthologous gene in M. tuberculosis Erdman, is functionally equivalent to Emp1. We identified at least 22 additional proteins that require Emp1 for acetylation, demonstrating that this putative NAT is not dedicated to EsxA. Finally, we showed that loss of emp1 resulted in a significant reduction in the ability of M. marinum to cause macrophage cytolysis. Collectively, this study identified a NAT required for N-terminal acetylation in Mycobacterium and provided insight into the requirement of N-terminal acetylation of EsxA and other proteins in mycobacterial virulence in the macrophage.