Biomaterial Database

The Semliki-Forest-virus-specific nonstructural protein nsP4 is an autoproteinase. 1990

K Takkinen, and J Peränen, and S Keränen, and H Söderlund, and L Kääriäinen

Institute of Biotechnology, University of Helsinki, Finland.

The Semliki-Forest-virus-specific nonstructural proteins are translated as a large polyprotein (2431 amino acid residues), from which the mature polymerase components nsP1, nsP2, and nsP4 are released by proteolytic cleavages. The complete ns polyprotein (P1234) can be cleaved in two alternative ways yielding either P123 (with sequences of nsP1, nsP2 and nsP3) and nsP4 or P12 (nsP1 plus nsP2) and P34 (nsP3 plus nsP4). We studied the possible autoproteolytic role of nsP4 involved in the cleavage between nsP3 and nsP4 in an in vitro transcription-translation system. cDNAs encoding P34 precursor and shorter precursor protein segments covering the nsP3-nsP4 cleavage region, were cloned under the T7 RNA polymerase promoter. The mRNAs synthesized in vitro were capped and translated in rabbit reticulocyte lysates. The translational products were analyzed by SDS/PAGE. The precursor proteins containing nsP4 sequences were cleaved yielding the products with expected sizes, indicating that the cleavage took place at the nsP3-nsP4 junction. By deleting and truncating the cDNA coding for nsP4, the proteolytic activity was mapped within the 102 amino-terminal amino acids of nsP4. The cleavage between nsP3 and nsP4 can be inhibited by pepstatin A and probably takes place in cis, since exogenously added nsP4 was unable to mediate it.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010447	Peptide Hydrolases	Hydrolases that specifically cleave the peptide bonds found in PROTEINS and PEPTIDES. Examples of sub-subclasses for this group include EXOPEPTIDASES and ENDOPEPTIDASES.	Peptidase,Peptidases,Peptide Hydrolase,Protease,Proteases,Proteinase,Proteinases,Proteolytic Enzyme,Proteolytic Enzymes,Esteroproteases,Enzyme, Proteolytic,Hydrolase, Peptide
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D002213	Capsid	The outer protein protective shell of a virus, which protects the viral nucleic acid. Capsids are composed of repeating units (capsomers or capsomeres) of CAPSID PROTEINS which when assembled together form either an icosahedral or helical shape.	Procapsid,Prohead,Capsids,Procapsids,Proheads
D003062	Codon	A set of three nucleotides in a protein coding sequence that specifies individual amino acids or a termination signal (CODON, TERMINATOR). Most codons are universal, but some organisms do not produce the transfer RNAs (RNA, TRANSFER) complementary to all codons. These codons are referred to as unassigned codons (CODONS, NONSENSE).	Codon, Sense,Sense Codon,Codons,Codons, Sense,Sense Codons
D005814	Genes, Viral	The functional hereditary units of VIRUSES.	Viral Genes,Gene, Viral,Viral Gene
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D012672	Semliki forest virus	A species of ALPHAVIRUS isolated in central, eastern, and southern Africa.
D012689	Sequence Homology, Nucleic Acid	The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.	Base Sequence Homology,Homologous Sequences, Nucleic Acid,Homologs, Nucleic Acid Sequence,Homology, Base Sequence,Homology, Nucleic Acid Sequence,Nucleic Acid Sequence Homologs,Nucleic Acid Sequence Homology,Sequence Homology, Base,Base Sequence Homologies,Homologies, Base Sequence,Sequence Homologies, Base
D014158	Transcription, Genetic	The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION.	Genetic Transcription