Temperature effect on Mycolic acid desaturase (desA1) activity of Mycobacterium smegmatis and Mycobacterium marinum, and further molecular assessment on the MadR function

Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis, remains a significant global health challenge, infecting millions and accounting for a substantial number of deaths annually. Despite its ancient association with humans and extensive research, fundamental questions persist regarding its pathogenesis. The Mycobacterial unique cell wall structure, constituted of mycolic acids, is a key virulence factor and a prime target for anti-TB drugs. However, the robustness of this cell wall enables the bacterium to adapt through various infection stages. The World Health Organization's ambitious goals of curbing TB incidence and related deaths by 2030 face new challenges, notably from the COVID-19 pandemic's indirect impacts and escalating drug resistance issues. Addressing these challenges demands innovative research strategies, including the development of safe and readily genetically modified model systems, and a deeper understanding of the TB bacillus's interaction with its host. In this project, the activity of desaturase (DesA1), an essential enzyme involved in mycolic acid synthesis, of both Mycobacterium smegmatis and Mycobacterium marinum is investigated when cultured under different temperature conditions to explore the impact of temperature on the formation of double bonds and cyclopropanated species. After mycolic acid analysis, it has been shown that the low temperature has a role in increasing the desaturation level, consequently, the fluidity. Furthermore, the significance of the V172 residue in the hydrophobic pocket of madR function is evaluated, emphasising its potential role in modulating the desaturase activity and the mycolic acid pattern subsequently. This study provides insights into potential avenues for therapeutic interventions against Mycobacterial infections.