Biophysical Society Thematic Meeting | Stockholm 2022

Physical and Quantitative Approaches to Overcome Antibiotic Resistance

Poster Abstracts

17-POS Board 17 CONTROLLED PARTITIONING OF RIFABUTIN INTO THE MYCOBACTERIAL ENVELOPE LAYERS DURING THE LATENT INFECTION STAGE Anjana Peethambaran Menon 1,2,3 ; Tzong-Hsien Lee 2,3 ; Marie-Isabel Aguilar 2,3 ; Shobhna Kapoor 1,3,4 ; 1 Indian Institute of Technology, Chemistry, Mumbai, India 2 Monash University, Department of Biochemistry and Molecular Biology, Clayton, Australia 3 Indian Institute of Technology, IITB-Monash Research Academy, Mumbai, India 4 Hiroshima University, Graduate School of Integrated Sciences for Life, Higashihiroshima, Japan Antitubercular chemotherapy has been successful in bringing down the death rate due to tuberculosis, however there are cases of patients surviving with persistent mycobacterium at the end of their treatment cycles. The combination of drugs fails to surpass the mycobacterial membrane at the latent stage of infection, leading to increased cases of resistance. This demands for the need to consider new markers or agents that could overcome the drug resistant variants and its occurrence. Mycobacterium has a highly complex membrane envelope which has spatially resolved outer and inner membrane layers with distinct compositions and membrane properties at both early and latent stage of infection. In this work, Rifabutin’s interaction with the cell envelopes of Mycobacterium smegmatis cultured to represent both the early and late infection stages were studied using a combination of biophysical methods to study the impact of membrane composition on drug interaction profile and hence resistance. UV-visible spectroscopic studies revealed a reduction in drug partitioning in the outer membrane, while the fluorescence quenching studies indicated a hindrance in the drug penetration across the inner membrane during the latent infection stage. However, surface plasmon resonance studies indicated a transient interaction of rifabutin, while it gets partitioned within different membranes. Altogether we demonstrated that the cell envelopes at different infection stages could control the drug entry into the cytoplasm, paving paths that lead to drug resistance. By leveraging the membrane-drug interaction profiles unique to mycobacteria at both the infection stages, specific chemotypes and anti-tubercular drugs can be designed to offer tractable insights into new combinational TB therapy.

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