Depurination of ribosomal RNA and inhibition of viral RNA translation by an antiviral protein of Celosia cristata.

An antiviral protein (25 kD) isolated from leaves of Celosia cristata (CCP 25) was tested for depurination study on ribosomal RNA from yeast. Ribosomal RNA yielded 360 nucleotide base fragment after treatment with CCP 25 indicating that CCP 25 was a ribosome inactivating protein. CCP 25 also inhibited translation of brome mosaic virus (BMV) and pokeweed mosaic virus (PMV) RNAs in rabbit reticulocyte translation system. The radioactive assay showed that incorporation of [35S]-methionine was less in translation proteins of BMV nucleic acid when CCP 25 was added to translation system. This indicated that antiviral protein from Celosia cristata not only depurinated ribosomal RNA but also inhibited translation of viral RNA in vitro.

Purification and properties of antiviral proteins from the leaves of Bougainvillea xbuttiana.

A non-phytotoxic, resistance inducing, proteinaceous antiviral principle was purified by ammonium sulphate fractionation, ion exchange chromatography and gel filtration from the leaves of Bougainvillea xbuttiana. It imparted resistance against tobacco mosaic virus (TMV) and sunnhemp rosette virus (SRV) in their respective test hosts viz. Nicotiana glutinosa, N. tabacum var. Samsun NN, and Cyamopsis tetragonoloba, respectively. The purified principle eluted as a single peak upon gel filtration, but exhibited two polypeptides on SDS-PAGE with Mr 28,000 and 24,000. The two polypeptides were found to be highly basic, rich in lysine with pI around 10.0 and 10.5, respectively. Since this principle effected local lesion inhibition in both treated and untreated top leaves of test host, it might be acting in the initial stages of virus infection as a systemic inducer.

Purification and characterization of a 29 kDa poly(A)-binding protein from chickpea (Cicer arietinum) epicotyl.

A poly(A)-binding protein (PABP) with mol wt 29,000 has been purified from chickpea (Cicer arietinum) epicotyl by ammonium sulfate fractionation and Cibacron blue F3-GA chromatography, making a complex with poly(A) and elution of PABP-poly(A) complex at 45 degrees C from oligo d(T)-cellulose. The elution pattern and binding properties show that the purified protein is different from the PABP (mol. wt 72,000) reported earlier from our laboratory.

Auxin regulated poly(A)polymerase activity in Cicer arietinum epicotyls.

There was a linear increase in poly (A+) polymerase activity in the C. arietinum epicotyls during germination. Six-day-old auxin treated seedlings showed about 3-4 fold stimulation in enzyme activity, accompanied with 3- fold rise in the relative abundance of poly (A+) RNA levels. Actinomycin D, cycloheximide, cordycepin and amino acid analogues caused dramatic decline in poly (A+) polymerase as well as poly (A+) RNA levels. It seems that auxin induced a de novo synthesis of this enzyme.

Purification and characterization of a poly(A)-binding protein from chickpea (Cicer arietinum) epicotyl.

A poly(A)-binding protein (PABP) with mol wt 72,000 has been purified from chickpea (Cicer arietinum) epicotyls by ammonium sulfate fractionation, Cibacron blue F3-GA and poly(A) agarose chromatography. The binding properties and the specificity of binding show that the purified protein is an analogue of PABPs in other eukaryotes. This PABP is highly susceptible to proteolysis and upon degradation forms a polypeptide fragment of mol wt 21,000 which has an independent poly(A) binding activity.

Blackgram mottle virus RNA and its in vitro translation.

In vitro translation of blackgram mottle virus RNA in rabbit reticulocyte lysate resulted in synthesis of five major virus specific polypeptides with mol wt 90,000(p90), 82,000(p82), 42,000(p42), 39,000(p39) and 32,000(p32), respectively. The polypeptide p39 was identified as coat protein based on its electrophoretic mobility and immunoprecipitation with BMoV-antiserum.