NSs Encoded by Groundnut Bud Necrosis Virus Is a Bifunctional EnzymeReportar como inadecuado

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Groundnut bud necrosis virus GBNV, a member of genus Tospovirus in the family Bunyaviridae, infects a large number of leguminosae and solanaceae plants in India. With a view to elucidate the function of nonstructural protein, NSs encoded by the small RNA genome S RNA, the NSs protein of GBNV- tomato Karnataka 1 was over-expressed in E. coli and purified by Ni-NTA chromatography. The purified rNSs protein exhibited an RNA stimulated NTPase activity. Further, this activity was metal ion dependent and was inhibited by adenosine 5′ β, γ imido triphosphate, an ATP analog. The rNSs could also hydrolyze dATP. Interestingly, in addition to the NTPase and dATPase activities, the rNSs exhibited ATP independent 5′ RNA-DNA phosphatase activity that was completely inhibited by AMP. The 5′ α phosphate could be removed from ssDNA, ssRNA, dsDNA and dsRNA thus confirming that rNSs has a novel 5′ α phosphatase activity. K189A mutation in the Walker motif A GxxxxGKT resulted in complete loss of ATPase activity, but the 5′ phosphatase activity was unaffected. On the other hand, D159A mutation in the Walker motif B DExx resulted in partial loss of both the activities. These results demonstrate for the first time that NSs is a bifunctional enzyme, which could participate in viral movement, replication or in suppression of the host defense mechanism.

Autor: Bhushan Lokesh, Panigrahi R. Rashmi, Bhat S. Amruta, Dharmaiah Srisathiyanarayanan, Mathur R. N. Murthy, Handanahal S. Savithri

Fuente: http://plos.srce.hr/


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