Characterization of mimivirus NAD+-dependent DNA ligase Journal Article
| Authors: | Benarroch, D.; Shuman, S. |
| Article Title: | Characterization of mimivirus NAD+-dependent DNA ligase |
| Abstract: | Mimivirus, a parasite of Acanthamoeba polyphaga, is the largest DNA virus known; it encodes a cornucopia of proteins with imputed functions in DNA replication, modification, and repair. Here we produced, purified, and characterized mimivirus DNA ligase (MimiLIG), an NAD+-dependent nick joining enzyme homologous to bacterial LigA and entomopoxvirus DNA ligase. MimiLIG is a 636-aa polypeptide composed of an N-terminal NAD+ specificity module (domain Ia), linked to nucleotidyltransferase, OB-fold, helix-hairpin-helix, and BRCT domains, but it lacks the tetracysteine Zn-binding module found in all bacterial LigA enzymes. MimiLIG requires conserved domain Ia residues Tyr36, Asp46, Tyr49, and Asp50 for its initial reaction with NAD+ to form the ligase-AMP intermediate, but not for the third step of phosphodiester formation at a preadenylylated nick. MimiLIG differs from bacterial LigA enzymes in that its activity is strongly dependent on the C-terminal BRCT domain, deletion of which reduced its specific activity in nick joining by 75-fold without affecting the ligase adenylylation step. The ΔBRCT mutant of MimiLIG was impaired in sealing at a preadenylylated nick. We propose that eukaryal DNA viruses acquired the NAD+-dependent ligases by horizontal transfer from a bacterium and that MimiLIG predates entomopoxvirus ligase, which lacks both the tetracysteine and BRCT domains. We speculate that the dissemination of NAD+-dependent ligase from bacterium to eukaryotic virus might have occurred within an amoebal host. © 2006. |
| Keywords: | gene deletion; nonhuman; mutant protein; protein domain; animals; carboxy terminal sequence; enzyme activity; tyrosine; bacteria (microorganisms); gene transfer; amino acid sequence; conserved sequence; molecular sequence data; sequence homology, amino acid; amino terminal sequence; enzyme analysis; dna viruses; eukaryota; mimivirus; nucleotide sequence; recombinant proteins; protein structure, tertiary; polydeoxyribonucleotide synthase; virus; molecular weight; aspartic acid; enzyme purification; cysteine; amino acid motifs; nicotinamide adenine dinucleotide; dna ligases; adenosine phosphate; adenylation; nucleotidyltransferase; liga; polypeptide; bacterial enzyme; phosphodiesterase; virus enzyme; dna virus; brct domain; acanthamoeba; acanthamoeba polyphaga; entomopoxvirinae; entomopoxvirus; virus characterization |
| Journal Title: | Virology |
| Volume: | 353 |
| Issue: | 1 |
| ISSN: | 0042-6822 |
| Publisher: | Elsevier Inc. |
| Date Published: | 2006-09-15 |
| Start Page: | 133 |
| End Page: | 143 |
| Language: | English |
| DOI: | 10.1016/j.virol.2006.04.032 |
| PUBMED: | 16844179 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 15" - "Export Date: 4 June 2012" - "CODEN: VIRLA" - "Source: Scopus" |
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