Products Cited in Publications Worldwide Proton gradient controls the lateral rearrangement of inner membrane domains in response to membrane fluidizer stress in Mycobacterium smegmatis

Proton gradient controls the lateral rearrangement of inner membrane domains in response to membrane fluidizer stress in Mycobacterium smegmatis

Prithviraj, Malavika; Shivangi, FNU; Freundlich, Joel S; Morita, Yasu S

DOI: PMID:

Abstract

Mycobacterium smegmatis partitions its plasma membrane into two distinct regions: the inner membrane domain (IMD) and the conventional plasma membrane. IMD, enriched in the subpolar regions of actively growing rod-shaped cell, contains many membrane proteins involved in cell envelope biosynthesis. Dibucaine, a membrane fluidizer, disrupts plasma membrane integrity and de-partitions the IMD from the sub-polar regions. We do not know what governs the de-partitioning of the IMD in response to dibucaine stress. In this study, we investigated the stress response of the IMD under respiration defect. We first depleted MenG, a key enzyme in the menaquinone biosynthesis, by CRISPRi and observed that the IMD does not respond to dibucaine-induced membrane stress. CRISPRi-induced knockdown of qcrC, a gene encoding a component of an electron transport chain cytochrome, corroborated the results of menG knockdown. In contrast, neither CRISPRi knockdown of atpD, a gene encoding a component of the ATP synthase nor inhibition of ATP synthase by bedaquiline inhibited the dibucaine-induced de-partitioning of sub-polar IMD as robustly as CRISPRi knockdowns of menG and qcrC. A pretreatment with the protonophore carbonyl cyanide m-chlorophenyl hydrazone (CCCP) prevented dibucaine-induced IMD de-partitioning. Furthermore, a pretreatment with nigericin, which acts as a H+/K+ antiporter and disrupts the proton gradient without affecting membrane potential, also inhibited the IMD de-partitioning in a way similar to CCCP. Taken together, our findings suggest that membrane stress-induced IMD delocalization is not a passive lipid dispersion but an active membrane rearrangement dependent on an electrochemical gradient of proton.

Keywords

membrane fluidity ; Mycobacterium ; plasma membrane ; proton motive force ; stress response

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