Further studies on the cardiolipin phosphodiesterase of Escherichia coli

Abstract

The cardiolipin phosphodiesterase of Escherichia coli was further characterized. This enzyme has a pH optimum of 7.0 and is Mg2+ dependent. Mn2+ and Co2+ could replace Mg2+ but other divalent cations were inhibitory or without effect. The enzyme is not periplasmic and does not appear to be associated with membrane fractions prepared by different methods. It is recovered as a soluble protein in the cytosol fraction but could not be readily purified because of its instability. With cell-free systems, a requirement for ATP or ADP could be shown under certain defined conditions. Other nucleotides were less effective or ineffective in stimulating the phosphodiesterase. The cells displayed the highest activity during the middle to late exponential stage but no marked requirement for ATP was apparent when the phosphodiesterase was obtained from such freshly grown cells. If, however, cells were starved for several hours in saline medium, the cardiolipin phosphodiesterase level fell and a requirement for added ATP could be shown. The cardiolipin phosphodiesterase is an enzyme distinct from cardiolipin synthase. The assay conditions are quite different from each of these enzymes as are their subcellular distributions.

Enzymology, genetics, and regulation of membrane phospholipid synthesis in Escherichia coli.

“…Evidence for phospholipase C is circumstantial, since it is based on the observation that phosphorylethanolamine is released from membranes in crude extracts (251,273). Proulx and co-workers have presented preliminary evidence for a soluble, cardiolipin-specific phospholipase D, but the combined action of several enzymes cannot be excluded under the conditions employed (25,(64)(65)(66). Phosphatidylserine is slowly hydrolyzed by homogeneous phosphatidylserine synthetase (Fig.…”

Complementary Sets of Autoantibodies Induced by SARS-CoV-2, Adenovirus and Bacterial Antigens Cross-React with Human Blood Protein Antigens in COVID-19 Coagulopathies

“…β2GPI also binds to PF4, F2, Factor X and CL [ 80 ]. In addition, platelet and endothelium phosphodiesterases bind CL [ 81 , 82 ], as do complement C1q-binding proteins, suggesting that cardiolipin and C1q share common epitopes, and providing a mechanism for activation of the complement cascade by anti-CL antibodies [ 83 ].…”