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M A Mayo

Publications and source records attributed to M A Mayo.

At least 73 records · Page 4Linked to original sources
PubMed1992

The nucleotide sequence of RNA-2 of raspberry ringspot nepovirus.

The nucleotide sequence of raspberry ringspot nepovirus (RRV) RNA-2 consists of 3928 nucleotides and a poly(A) tract at the 3' end. RNA-2 contains one open reading frame which encodes a polypeptide of M(r) 123508 (123K). Edman degradation located the N terminus of the coat protein 514 residues from the C-terminal end of the 123K protein, which suggests that the coat protein is released from the polyprotein by cleavage of a C-A bond. The RRV coat protein has some sequence similarities with the coat proteins of other nepoviruses, but is no more like any one nepovirus than another. In contrast, the portion of the 123K protein to the N-terminal side of the coat protein is similar in sequence to the corresponding parts of the polyproteins of tomato black ring and grapevine chrome mosaic nepoviruses, though not to those of other nepoviruses.

Amino Acid Sequence↗
PubMed1991

The 5'-terminal sequence of potato leafroll virus RNA: evidence of recombination between virus and host RNA.

The discrepancy between published sequences of the 5' non-coding regions of RNA of a Scottish (S) and that of Dutch (D), Australian and Canadian isolates of potato leafroll virus (PLRV) was investigated. Reverse transcription followed by amplification by polymerase chain reaction showed that RNA from three distinct Scottish isolates of PLRV contained molecules with 5' ends like that of the original Scottish isolate. However, determination of the 5'-terminal sequences of RNA in two of these preparations showed that most RNA molecules had 5' termini like those of the Dutch and other non-Scottish sequences. Northern blot analysis confirmed that only a small fraction of PLRV RNA contained sequences homologous to the 5'-terminal 119 nucleotides of the PLRV-S sequence. Most PLRV-S RNA molecules therefore have termini like that reported for PLRV-D. The 5'-terminal 119 nucleotides of the minor species of PLRV-S RNA were very similar (109/119 nucleotides were identical) in sequence to an exon of tobacco chloroplast DNA open reading frame 196. The results therefore suggest that recombination has occurred between virus RNA and host RNA.

Base Sequence↗
PubMed1991

The location of the 5' end of the potato leafroll luteovirus subgenomic coat protein mRNA.

Northern blot analysis of nucleic acid from potato plant tissues and tobacco protoplasts infected with a Scottish isolate of potato leafroll luteovirus (PLRV) detected the 6 kb genomic RNA and one subgenomic RNA species of about 2.7 kb; RNA extracted from virus particles contained only the genomic species. Blotting with small defined probes suggested that the location of the 5' end of the subgenomic RNA was between 2380 and 2510 nucleotides from the 3' end of the PLRV genome (between 3370 and 3500 nucleotides from the 5' end of PLRV Dutch isolate RNA). When RNA extracted from PLRV-infected or mock-inoculated protoplasts was used as the template for primer extension using primers complementary to the sequence at, or upstream of, the initiation codon of the coat protein gene, a single major infection-specific product was detected. A primer complementary to the sequence between 162 and 179 nucleotides upstream of the coat protein AUG yielded a product of 56 nucleotides. Thus, the subgenomic RNA has a leader sequence of 212 nucleotides, is 2505 nucleotides in length and starts at a position equivalent to 3376 nucleotides from the 5' end of the PLRV-Dutch genome, 11 nucleotides upstream of the termination codon of the putative polymerase gene. The nucleotide sequence immediately downstream of this position closely resembles that of the 5' end of the PLRV genomic RNA.

Base Sequence↗
PubMed1991

Nucleotide sequence of raspberry bushy dwarf virus RNA-3.

A nucleotide sequence is reported for RNA-3, the smallest of the three major RNA species found in particles of raspberry bushy dwaft virus (RBDV). The sequence of 946 nucleotides contains a single large open reading frame which encodes an Mr 30,509 polypeptide. In vitro translation of RNA-3 yielded an Mr 30,000 product that reacted specifically with antiserum to RBDV particles and we conclude that the amino acid sequence deduced from the sequence of RNA-3 is that of the RBDV coat protein, or an immediate precursor of it. No affinities were detected by comparing the nucleotide sequence of RNA-3 with the sequences of other plant viruses.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence of raspberry bushy dwarf virus RNA-2: a bicistronic component of a bipartite genome.

Northern blot analysis with cDNA probes to RNA-3 (1 kb) of raspberry bushy dwarf virus (RBDV) revealed extensive sequence homology with RBDV RNA-2 (2.2 kb). Nucleotide sequencing showed that RNA-2 contains two large open reading frames (ORFs), of 1074 (5' ORF) and 822 (3' ORF) bases. The 3' ORF is virtually identical in sequence to RNA-3, which encodes the Mr 30509 (30K) coat protein. The 5' ORF encodes an Mr 38860 (39K) protein which slightly resembles the 32K protein encoded by RNA-3 of alfalfa mosaic virus (AlMV). RBDV RNA-2 resembles AlMV RNA-3 in being bicistronic and encoding a coat protein at the 3' end. Comparing RNA-1 and RNA-2 of RBDV, only the 18 3'-terminal nucleotides are identical in sequence but the 3'-terminal 71 nucleotides of each RNA species have the potential to form similar stem-loop structures.

Amino Acid Sequence↗
PubMed1990

Expression of the genome of potato leafroll virus: readthrough of the coat protein termination codon in vivo.

An antiserum was raised against a fusion protein containing part of the 56K polypeptide (P5) encoded by the open reading frame (ORF) at the 3' end of the genome of potato leafroll virus (PLRV). This antiserum reacted specifically with 80K and 90K polypeptides in PLRV-infected protoplasts, with a 90K polypeptide in infected potato tissue and with a 53K polypeptide in protein extracted from purified particles of PLRV. Monoclonal antibodies raised against purified PLRV particles also reacted with these polypeptides, as well as with the 23K coat protein. Virus particles partially purified from infected protoplasts contained some 90K polypeptide as well as the major 23K coat protein. The ORFs of the 23K coat protein and P5 are contiguous and in frame. The results suggest that the P5 polypeptide of PLRV occurs in infected cells as part of a readthrough protein comprising the 23K coat protein joined to the P5 amino acid sequence. Moreover the readthrough protein can be assembled into virus particles as a minor component together with the main 23K component. The P5 protein may thus contribute to properties of PLRV determined by its virus particle surface.

Blotting, Western↗
PubMed1990

Unusual electrophoretic properties of the coat protein of raspberry ringspot nepovirus.

Coat protein of raspberry ringspot nepovirus (RRV) migrated during electrophoresis in a discontinuous buffer system as two components which were capable of interchanging during this procedure. However, only one component was formed during electrophoresis in a continuous buffer system. Treatment of the protein before electrophoresis with iodoacetamide, which alkylates sulfhydryl groups, prevented the formation of the faster migrating electrophoretic component. Thus the faster migrating component is probably an artifact caused by S-S bond formation. Although the coat proteins of two other nepoviruses did not behave in this way, the results obtained with RRV emphasize the need for caution in interpreting electrophoretic heterogeneity in virus proteins. The estimated molecular weight of RRV coat protein was 57,000.

Buffers↗
PubMed1989

Nucleotide sequence of potato leafroll luteovirus RNA.

A sequence of 5987 nucleotides is reported for the RNA of potato leafroll luteovirus (PLRV). The sequence contains six large open reading frames, and non-coding regions of 174 nucleotides at the 5' end, 141 nucleotides at the 3' end and 197 nucleotides between two large blocks of coding sequences. The 5' coding region encodes two polypeptides of 28,000 (28K) and 70K which overlap in different reading frames and circumstantial evidence suggests that the third open reading frame in the 5' block is translated by frameshift readthrough near the end of the 70K polypeptide to give a 118K polypeptide. The C-terminal part of the 118K protein contains the consensus sequence for RNA-dependent RNA polymerases. In vitro translation of PLRV RNA resulted in the synthesis mainly of 28K and 70K polypeptides and the largest product made was about 125K; these sizes are similar to those predicted for the translation products of the 5' block of coding sequence. The 3' block of coding sequence codes for three polypeptides: a 23K coat protein, a 17K polypeptide which is encoded in a different frame, and a 53K polypeptide which immediately follows the coat protein coding sequence, and is in the same reading frame. Circumstantial evidence suggests that the 53K polypeptide is translated by readthrough of the amber termination codon of the coat protein gene. The amino acid sequences encoded by the 3' block of coding sequence show many similarities with analogous polypeptides translated from the nucleotide sequences of RNA of barley yellow dwarf virus, PAV strain (BYDV) and, in particular, beet western yellows virus (BWYV). The 118K polypeptide has some similarities with the putative polymerase of southern bean mosaic virus and much more extensive similarities with the corresponding BWYV polypeptide but almost none with that of BYDV. In contrast, the amino acid sequence of the 28K polypeptide is not like that of proteins of the other luteoviruses or of viruses in other groups. The nucleotide sequences reported will appear in the EMBL, GenBank and DDBJ databases under the accession number X14600.

Amino Acid Sequence↗
PubMed1982

Polypeptides induced by tobacco rattle virus during multiplication in tobacco protoplasts.

Tobacco protoplasts were irradiated with UV light, inoculated with tobacco rattle virus (TRV), and then cultured in media containing 35S-methionine. Polypeptides induced by TRV infection were detected by PAGE of protein extracts. Three 35S-labeled polypeptides (apparent molecular weights 187,000, 142,000, and 31,000) occurred in extracts of virus-infected protoplasts but not in extracts of buffer-inoculated protoplasts. The 31,000 mol. wt. polypeptides co-migrated with TRV coat protein in polyacrylamide gels and was not detected when inocula contained only the longer particle of TRV. The 187,000 and 142,000 mol. wt. polypeptides migrated in positions very close to products of in vitro translation of TRV RNA-1. Experiments in which 35S-methionine was supplied at different times during multiplication suggested that the bulk of translation of RNA-1 occurred sooner after inoculation than did that of RNA-2.

Plant Viruses↗
PubMed1978

The effect of protoplast concentration during inoculation on the infection of tobacco protoplasts.

When tobacco protoplasts were inoculated with tobacco rattle virus, the proportion infected was inversely related to the protoplast concentration between 0.5 X 10(5) and 4 X 10(5) per milliliter when the inocula contained phosphate or Tris-HCL buffers, but was independent of protoplast concentration when using citrate buffer. The decrease in infection obtained at high protoplast concentrations in phosphate was diminished by increasing the poly-L-ornithine (PLO) concentration. At usual PLO concentrations, inocula in phosphate produced more infection that those in citrate, but at some suboptimal PLO concentrations the position was reversed. These effects may result from differences in the reaction between PLO and the different buffer anions.

Buffers↗
PubMed1975

Revision of estimates of the molecular weights of tobravirus coat proteins.

The molecular weights of proteins from several tobacco rattle viruses (or tobraviruses) have been determined by electrophoresis with 'marker' proteins in acrylamide gels of different strengths. Plotting KR, a measure of the effect of varying the gel strength, against molecular weight gave a value of 23,000 +/- 2,800 for tobacco rattle virus (TRV) strain CAM and similar values for other strains of TRV and pea early-browning virus. A value of 21,700 +/- 700 was obtained for TRV strain PRN by sedimentation to equilibrium in 6 M guanidine hydrochloride. These estimates are similar to those made by a statistical reappraisal of published data on amino acid composition, and a value of about 22,000 is proposed for TRV coat proteins.

Molecular Weight↗