ABHD18 degrades cardiolipin by stepwise hydrolysis of fatty acids.
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ABHD18 is functionally homologous to yeast Cld1 and is the long-sought lipase that hydrolyses cardiolipin in mice and flies.
"we
demonstrate that α/β-hydrolase domain 18 (ABHD18), a highly conserved protein of
plants, animals, and humans, is functionally homologous to Cld1."
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Deacylation is stepwise rather than removal of a single fatty acid, proceeding past monolysocardiolipin.
"Rather than removing just one fatty acid, we show
that ABHD18 deacylates CL further."
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ABHD18 catalyses the breakdown of cardiolipin while tafazzin protects cardiolipin from degradation.
"Thus, ABHD18 catalyzes the breakdown of CL,
whereas TAZ protects CL from degradation."
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Abhd18 knockdown decreased monolysocardiolipin in murine Taz-knockout myoblasts, and Drosophila inactivation increased cardiolipin abundance.
"Knockdown of
Abhd18 decreased the concentration of MLCL in murine, Taz-knockout myoblasts."
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The authors explicitly dissent from the orthodox remodelling mechanism and place ABHD18's degradative activity outside it, while still describing ABHD18 as participating in TAZ-catalysed remodelling - which is why GO:0035965 is retained rather than removed.
"This is inconsistent with the orthodox remodeling mechanism but suggests that ABHD18 and TAZ have opposing effects on CL metabolism."
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The same Discussion states the participation directly, so the dissenting paper itself supports retaining the remodelling process annotation.
"Apart from its participation in TAZ-catalyzed remodeling, ABHD18 alters the CL species composition by species-selective degradation."