Polypeptides associated with inclusion bodies from leaves of turnip infected with cauliflower mosaic virus

Abstract

Inclusion bodies, the major intracellular site of accumulation of cauliflower mosaic virus (CaMV), have been partially purified by centrifugation onto a saturated sucrose cushion, followed by detergent treatment to lyse chloroplasts, then centrifugation on a saturated sucrose cushion again. The resulting preparation was enriched for inclusion bodies as judged by light and electron microscopic observation and by sodium dodecyl sulfatepolyacrylamide gel electrophoresis of the polypeptides in the preparation. Two major polypeptides of 61,000 and 43,000 apparent molecular weights were found in inclusion body preparations from leaves infected separately with each of three different isolates of CaMV. Polypeptides of apparent molecular weights 56,000, 50,000, 39,000, 37,000, and 34,000 were also detected in preparations from infected leaves, but not in comparable preparations from healthy leaves. The mobilities of all but the 61,000 and 34,000 molecular weight polypeptides were slightly different from the CM4-184 isolate, as compared with Cabbage B Davis or NY8153. The 61,000 molecular weight polypeptide did not correspond in mobility to any of the virion polypeptides. The relative intensities of polypeptide bands common to inclusion bodies and isolated virions were different in these two preparations, suggesting that considerable degradation took place during virion isolation.