Sequence analysis reveals a conserved extension in the capping enzyme of the alphavirus supergroup, and a homologous domain in nodaviruses

Table 1 Published deletions or mutations within the Iceberg region of the MTase-GTase of the alphavirus supergroup that inhibit its enzymatic activities

				Activity compared to wild-type ¹
Group	Genus	Species	Substitution/Deletion	MTase ²	GTase ³
Alto	Alphavirus	Semliki Forest virus [11,22]	K317A	5%	2%
			Δ270-537	<1%	<1%
			Δ430-537	<1%	<1%
		Sindbis virus [21]	Δ287-417	<1%	<1%
		Sindbis virus [21]	Δ442-492	<1%	<1%
			W222A	5%	nd
			C234A	28%	15%
			W296A	17%	nd
			Y299A	58%	nd
			D310A	10%	5%
			W312A	37%	18%
Tymo	Potexvirus	Bamboo mosaic virus [40,20]	R316A	51%	19%
			Y338A	16%	nd
			F339A	20%	nd
			Y340A	23%	nd
			K344A	14%	14%
			W406A	14%	1%
			K409A	59%	40%

¹In all cases, the mutant proteins were produced in E. coli. Only point substitutions (replacement by alanine) or deletions giving a significant reduction in activity (<60% of wild type) are shown. MTase: guanine-7-methyltransferase activity; GTase: covalent m⁷GMP binding activity; nd: not determined.

ISSN: 1745-6150