Dual RNase and β-lactamase activity of a single enzyme encoded in most Archaea

Abstract

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A metallo-beta-lactamase with both beta-lactamase and ribonuclease activity is linked with traduction in giant viruses

“…The recombinant protein AUL78925.1 of Tupanvirus deep ocean (named TupBlac) was expressed in Escherichia coli and was then purified, as described previously 6 . Based on the phylogenetic analysis and as MBL folds can hydrolyse nucleic acids 2 , both beta-lactamase and nuclease activities of this purified protein were thereafter tested.…”

“…Beta-lactamases are a priori useless for giant viruses, which are grown in the presence of various antibiotics, including beta-lactams 24 , but our findings enhance the recent reconsideration of the function of MBL fold proteins. Thus, the recent description of penicillin secretion by arthropods 25 and the demonstration of active beta-lactamase in vertebrates including humans 19 , as well as in archaea 6 and fungi 26 show that MBL fold proteins have a dramatically broad distribution. In humans, 18 genes were annotated as beta-lactamases, whose activity had not been biologically-tested until recently 19 .…”

“…A pure solution of Tupanvirus protein was buffer-exchanged in PBS and the concentration was adjusted to 1 mg/ml. The degradation of nitrocefin (1 mM in PBS), a chromogenic cephalosporin substrate, was monitored as previously described after the addition of virion protein extract or Tupanvirus protein to the solution 6 .…”

“…Then, 70 μL of acetonitrile were added to each sample, and tubes were vortexed 10 minutes at 16,000 g to precipitate the proteins. The clear supernatant was collected for analysis using an Acquity I-Class UPLC chromatography system connected to a Vion IMS Qtof ion mobility-quadrupole-time of flight mass spectrometer, as previously described 6 .…”

“…Nevertheless, this hydrolase activity is suspected to have evolved in response to the environmental beta-lactams from an ancestral protein whose function was not related to beta-lactams and which may have been devoid of such hydrolase capability 3 . Concurrently to their capability to interact with various substrates that likely emerged through adaptive evolution, members of the MBLs superfamily have been identified in a broad range of cellular organisms, including bacteria, but also eukaryotes and archaea with a beta-lactamase activity 2,6 .…”