Biomaterial Database

Mutational analysis of the pseudoknot region in the 3' noncoding region of tobacco mosaic virus RNA. 1990

N Takamatsu, and Y Watanabe, and T Meshi, and Y Okada

Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.

The approximately 200-nucleotide-long 3'-terminal noncoding region of tobacco mosaic virus (TMV) RNA contains a tRNA-like structure and, in its immediate upstream region, three consecutive pseudoknots, each of which is composed of two double-helical segments. To elucidate the biological functions of the pseudoknot region, we constructed several deletion mutant TMV-L (a tomato strain) RNAs by using an in vitro transcription system and tested their ability to multiply in both tobacco plants and protoplasts. When deletions were introduced just downstream of the termination codon of the coat protein gene in the 5'-to-3' direction progressively, five of six double-helical segments were dispensable for viral multiplication, indicating that the pseudoknot structures are not essential for multiplication. However, extension of the deletion into the central pseudoknot region resulted in reduction in viral multiplication, accompanied by loss of development of mosaic symptoms on systemic tobacco plants. Cessation of multiplication was observed when the sequence involved in formation of double-helical segment I just upstream of the tRNA-like structure was deleted irrespective of the start point and extent of deletion. Point mutations that destabilized double-helical segment I resulted in a loss or great reduction of viral multiplication, whereas the double mutants in which the double helix was restored by additional compensating base substitutions restored multiplication to nearly the wild-type level. Thus, double-helical segment I just upstream of the tRNA-like structure is a structural feature essential for viral multiplication.

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
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D010947	Plants, Toxic	Plants or plant parts which are harmful to man or other animals.	Plants, Poisonous,Plant, Poisonous,Plant, Toxic,Poisonous Plant,Poisonous Plants,Toxic Plant,Toxic Plants
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
D011523	Protoplasts	The protoplasm and plasma membrane of plant, fungal, bacterial or archaeon cells without the CELL WALL.	Protoplast
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
D002872	Chromosome Deletion	Actual loss of portion of a chromosome.	Monosomy, Partial,Partial Monosomy,Deletion, Chromosome,Deletions, Chromosome,Monosomies, Partial,Partial Monosomies
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
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA