Relevance of the N-terminal and major hydrophobic domains of non-structural protein 3A in the replicative process of a DNA-launched foot-and-mouth disease virus replicon
A foot-and-mouth disease virus (FMDV) DNA-launched reporter replicon containing a luciferase gene was used to assess the impact of non-structural (NS) protein 3A on viral replication. Independent deletions within the N-terminal region (amino acid [aa] residues 6 to 24) and the central hydrophobic region (HR, aa 59 to 76) of FMDV NS protein 3A were engineered, and luciferase activity in lysates of control and mutated replicon-transfected cells was measured. Triple alanine replacements of the N-terminal triplet Arg 18- His 19 -Glu 20 and a single alanine substitution of the highly charged Glu 20 residue both resulted in a 70-80% reduction in luciferase activity when compared with wild-type controls. Alanine substitution of the 17 aa present in the central HR, on the other hand, resulted in complete inhibition of luciferase activity and in the accumulation of the mutated 3A within the cell nucleus according to immunofluorescence analysis. Our results suggest that both the aa sequence around the putatively exposed hydrophilic E20 residue at the N-terminus of the protein and the hydrophobic tract located between aa 59 and 76 are of major relevance for maintaining the functionality of the 3A protein and preventing its mislocalization into the cell nucleus.
This work was supported by the Fondo Nacional de Ciencia y Tecnología (FONCyT) and Consejo Nacional de Investigaciones Científicas y Tecnológicas of Argentina (CONICET). We are grateful to Dr. Nora Lopez and Dr. Sabrina Foscaldi for providing the pTM1-Renilla plasmid. CL and AG are graduate fellows from CONICET. MW, PRG and NM are at the Scientific Researcher Career in CONICET.
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Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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