Date of Award
1994
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Biology
Abstract
The toxin-coding gene of Ustilago maydis virus P4 has been identified, cloned and sequenced. The putative toxin-coding dsRNA segment (M2a) was isolated from a co-migrating dsRNA (M2b) by 5% polyacrylamide gel electrophoresis under modified conditions. The M2a dsRNA segment was found to be the putative toxin-coding gene by Northern hybridization analysis. The cloned M2a sequence was found to contain an open reading frame of 127 amino acids which represents the preprotoxin. The 22-amino acid N-terminal region is processed to yield the mature toxin which is secreted. A complete match (except 6 amino acids) was obtained between the deduced amino acid sequence and the partial 57 amino acid sequence obtained directly from the purified mature toxin. N-glycosylation-specific sequences were not found in the primary sequence. The co-migrating M2b dsRNA segment was also cloned and sequenced. It contained an open reading frame of 79 amino acids. The deduced amino acid sequence shows two KEX-2 like cleavage sites and two N-glycosylation sites. A sequence comparison on the Genbank did not show significant homology with listed proteins; however, 100% identity of the M2b open reading frame was detected with the partial open reading frame reported for UmVP1 M2 dsRNA segment, and 97% homology was found at the nucleotide level.
Recommended Citation
Khimani, Anis Haroon, "Identification Of The Toxin-Codingdsrna Segment Of Ustilago Maydis Virus P4" (1994). All-Inclusive List of Electronic Theses and Dissertations. 818.
https://scholars.indianastate.edu/etds/818