Mutational analysis of vaccinia virus nucleoside triphosphate phosphohydrolase I, a DNA-dependent ATPase of the DExH box family Journal Article
| Authors: | Martins, A.; Gross, C. H.; Shuman, S. |
| Article Title: | Mutational analysis of vaccinia virus nucleoside triphosphate phosphohydrolase I, a DNA-dependent ATPase of the DExH box family |
| Abstract: | Vaccinia virus nucleoside triphosphate phosphohydrolase I (NPH-I) is a DNA-dependent ATPase that serves as a transcription termination factor during viral mRNA synthesis. NPH-I is a member of the DExH box family of nucleic acid-dependent nucleoside triphosphatases (NTPases), which is defined by the presence of several conserved sequence motifs. We have assessed the contributions of individual amino acids (underlined) in motifs I (GxGKT), II (DExHN), III (SAT), and VI (QxxGRxxR) to ATP hydrolysis by performing alanine scanning mutagenesis. Significant decrements in ATPase activity resulted from mutations at nine positions: Lys-61 and Thr-62 (motif I); Asp-141, Glu-142, His-144, and Asn-145 (motif II); and Gln-472, Arg-476, and Arg-479 (motif VI). Structure-function relationships at each of these positions were clarified by introducing conservative substitutions and by steady-state kinetic analysis of the mutant enzymes. Comparison of our findings for NPH-I with those of mutational studies of other DExH and DEAD box proteins underscores similarities as well as numerous disparities in structure- activity relationships. We conclude that the functions of the conserved amino acids of the NTPase motifs are context dependent. |
| Keywords: | gene mutation; polymerase chain reaction; protein analysis; steady state; phosphatase; enzyme activity; acid anhydride hydrolases; structure activity relation; structure-activity relationship; dna; amino acid sequence; enzyme analysis; vaccinia virus; binding sites; adenosine triphosphate; adenosine triphosphatase; adenosine triphosphatases; hydrolysis; thin layer chromatography; mutagenesis; rna splicing; amino acid analysis; virus mutation; repressor gene; nucleoside triphosphate; virus enzyme; nucleoside-triphosphatase; priority journal; article |
| Journal Title: | Journal of Virology |
| Volume: | 73 |
| Issue: | 2 |
| ISSN: | 0022-538X |
| Publisher: | American Society for Microbiology |
| Date Published: | 1999-02-01 |
| Start Page: | 1302 |
| End Page: | 1308 |
| Language: | English |
| PUBMED: | 9882335 |
| PROVIDER: | scopus |
| PMCID: | PMC103954 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 16 August 2016 -- Source: Scopus |
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