Properties of viruses of the potyvirus group. 2. Buoyant density, S value, particle morphology, and molecular weight of the coat protein subunit of bean yellow mosaic virus, pea mosaic virus, lettuce mosaic virus, and potato virus YN

Abstract

The buoyant densities of bean yellow mosaic virus (BYMV) B25, pea mosaic virus (PMV) E198, lettuce mosaic virus (LMV), and potato virus yN (pVyN) were 1.318, 1.321, 1.330, and 1.326 g/ml, respectively. Their S values were 143, 140, 143, and 145 S. The particle morphology of BYMV B25, PMV E198, and LMV could reversibly be changed by magnesium ions. PVY N particles were broken in the presence of magnesium ions. The molecular weight of the coat protein subunit of the four viruses was 34,000 daltons. In many preparations also a 28,000 daltons component was present. This must be considered to be a breakdown product, derived from the 34,000 daltons component by proteolytic activity.

The nucleotide sequence of the coat protein gene and 3? untranslated region of papaya ringspot virus type W (Aust)

“…If this prediction is correct for PRSV-W (Aust) then the amino acid sequence obtained by N-terminal sequencing may be derived from a degradation product of PRSV-W coat protein. This suggestion is supported by the facts that: (/) in some of our virus preparations minor low molecular weight bands have been detected by potyacrylamide gel electrophoresis (results not shown) and similar bands, shown to be proteolytic fragments have been reported with other potyviruses [8,9,11]; (i0 it has been reported that potyviral coat proteins exhibit blocked N-termini, usually acetyl-serine [16], which therefore would not be sequenced by standard Edman chemistry; (iii) only 20% of the available protein was able to be sequenced.…”

The N and C Termini of the Coat Proteins of Potyviruses Are Surface-located and the N Terminus Contains the Major Virus-specific Epitopes

“…4d). The results also showed that the three antisera reacted with lower Mr degradation products of the coat protein (Huttinga & Mosch, 1974;Moghal & Francki, 1976;Hiebert et al, 1984). The higher Mr bands seen in some lanes in Fig.…”

“…2) with cleavage sites not specific for trypsin. These peptides may have resulted from the action of proteases of plant or microbial origin which can cosediment with potyvirus particles during purification (Huttinga & Mosch, 1974;Moghal & Francki, 1976;Hiebert et al, 1984). The presence of similar minor peaks in the chromatograms of other potyviruses (Fig.…”

“…Other conditions were the same as described for trypsin treatment (D. D. Shukla, J. Jilka, M. Tosic & R. E. Ford, unpublished results). Previously reported heterogeneity of potyvirus coat protein molecules has been attributed to degradation in situ by plant cell proteases (Moghal & Francki, 1976) or to degradation by contaminating host or microbial proteases during purification and storage (Huttinga & Mosch, 1974;Moghal & Francki, 1976;Hiebert et al, 1984). Both postulates were examined.…”

Nucleotide sequence of the 3′ terminal region of lettuce mosaic potyvirus RNA shows a Gln/Val dipeptide at the cleavage site between the polymerase and the coat protein

“…3). The native coat protein was considered • Cleavage site involved in the production of the capsid protein to correspond to the major band at 35k; this apparent molecular weight of the major product is in agreement with the values estimated previously [36,44]. To define the exact location of the coat protein gene, the sequence of the N-terminal region of the 35k protein was chemically determined.…”