Consequences of the Inhibition of Cardiolipin Metabolism in Haemophilus parainfluenzae

Abstract

Examination of phospholipid metabolism in Haemophilus parainfluenzae with inhibitors of various cellular functions-indicated that macromolecular synthesis and lipid metabolism can be dissociated at least for a short time. Two classes of inhibitors have relatively specific effects on cardiolipin (CL) metabolism. Pentachlorophenol and p-hydroxymercuribenzoate blocked CL synthesis but allowed CL hydrolysis to phosphatidic acid and phosphatidyl glycerol (PG); 3,3',4,5'-tetrachlorosalicylanilide (TCS) and carbonyl cyanide m-chlorophenylhydrazone (m-CCCP) blocked CL hydrolysis with the stoichiometric accumulation of CL. It appeared as if TCS and m-CCCP inhibited a vital activity coupled with the hydrolysis of CL by the highly active, CL-specific phospholipase D found in this organism. Because TCS and m-CCCP are thought to act by destroying the proton gradient thereby interrupting energy-dependent transport, it is possible that a highly active portion of the cellular CL could be coupled to some phase of this process.

A Pseudomonas putida cardiolipin synthesis mutant exhibits increased sensitivity to drugs related to transport functionality

“…In comparison with wild-type cells, the most relevant phenotype of the cls mutant strain was its increased sensitivity to exposure to toxic compounds that are eliminated from the cell via RND (resistance, nodulation, cell division) efflux pumps. This is in agreement with the pioneering observation made in Dr White's laboratory that inhibition of CL synthesis in Haemophilus parainfluenza by certain drugs interfered with their extrusion by interrupting energy-dependent transport systems (Ono and White, 1971). In this regard phospholipids have been shown to play an important role in the stabilization of protein complexes, in protein folding and insertion in the membranes, translocation across membranes, and orientation of transmembrane domains within the membrane (Kusters et al, 1991;Klompenburg et al, 1998;Bogdanov et al, 2002;Zhang et al, 2002;Pfeiffer et al, 2003).…”

“…Changing the proportions of anionic phospholipids may alter some of the divisional processes, which could lead to cell division before the cell has reached the average size of the wild-type cells. Several reports have suggested that CL participates in resistance to several stresses such as starvation, toxic chemicals, heat or saline environments (Ono and White, 1971;Hiraoka et al, 1993). However, P. putida DOT-T1E cls mutants were not more severely affected than the wild type by most of the different stresses we tested.…”

“…Cardiolipin in other microorganisms has been suggested to participate in different stress responses (Ono and White, 1971;Hiraoka et al, 1993;Inoue et al, 1997;Shiba et al, 2004). To find out what kind of stress responses were affected in the P. putida DOT-T1E cls mutant we tested the survival of wild-type and mutant strains in response to different stress conditions.…”

Compensatory role of the cis‐trans‐isomerase and cardiolipin synthase in the membrane fluidity of Pseudomonas putida DOT‐T1E

“…This proposal by Bernal and colleagues (2007) is based on the fact that the rate of accumulation of ethidium bromide in P. putida cls mutant cells was higher than in wild-type cells. The observation that the functioning of efflux transporters could be influenced by bacterial phospholipid composition was already envisaged by White's group some 30 years ago (Ono and White, 1971). Consistent with the rigidity studies described above, our present results show that the entry of ethidium bromide into carbonyl cyanide 3-chlorophenyl hydrazone-treated cti mutant cells was 1.4-fold faster than in the parental strain, whereas the rate of entry in the cls mutant was 1.4-fold slower, and the introduction of a cls mutation into the cti mutant produced a compensatory effect, so that the rate of entry was similar to that determined for the wildtype strain.…”

Biosynthesis of Cardiolipin from Phosphatidylglycerol in Staphylococcus aureus

“…The hydrophobic 820 diglyceride ends seem to be metabolically stable, but the glycerol diphosphate in the middle undergoes rapid synthesis and hydrolysis from a small portion of the phosphatidylglycerol (PG) pool in H. parainfluenzae and Staphylococcus aureus (20,27). Inhibitors of oxidative phbsphorylation and proton gradient formation, like carbonylcyanide-chlorophenolhydrazone (m-CCCP) or tetrachlorosalicylanilide, inhibited an activity coupled to the rapid metabolism of CL but had no effect on the isolated phospholipase D in vitro (16). The unique localization of CL in the inner membrane of the mitochondria and the fact that the rapid metabolism of CL in bacteria was coupled to components in the membrane involved in oxidative phosphorylation suggested some possible role for CL in the electron transport system.…”