| Type: | Domain | Name: | (+) RNA virus helicase core domain |
| Description: | Helicases have been classified in 6 superfamilies (SF1-SF6) []. All of theproteins bind ATP and, consequently, all of them carry the classical Walker A (phosphate-binding loop or P-loop) and Walker B(Mg2+-binding aspartic acid) motifs. The two largest superfamilies, commonly referred to as SF1 and SF2, share similar patternsof seven conserved sequence motifs, some of which are separated by long poorly conserved spacers. Helicase motifs appear to be organised in a core domainwhich provides the catalytic function, whereas optional inserts and amino- and carboxy-terminal sequences may comprise distinct domains with diverseaccessory roles. The helicase core contains two structural domains, an N- terminal ATP-binding domain and a C-terminal domain. Putative SF1 helicasesare extremely widespread among positive-stranded (+)RNA viruses. They have been identified in a variety of plant virus families, as well as alpha- rubi-,arteri-, hepatitis E, and coronaviruses. A number of these viral enzymes have been implicated in diverse aspects of transcription and replication but alsoin RNA stability and cell-to-cell movement [].The (+) RNA virus helicase core contains two RecA-like alpha/beta domains. The N-terminal ATP-binding domain contains a parallel six- stranded beta-sheet surrounded by four helices on one side and two helices onthe other. The C-terminal domain contains a parallel four-stranded beta-sheet sandwiched between two helices on each of its sides. The (+)RNA virus helicasecore is likely to bind NTP in cleft between the N terminus of the ATP-bindingdomain and the beginning of the C-terminal domain [].This entry represents the (+)RNA virus helicase core domain. | Short Name: | (+)RNA_virus_helicase_core_dom |
