Open AccessCharacterization of RNA polymerase III transcription factor TFIIIC from the mulberry silkworm, Bombyx mori
Author(s) -
Srinivasan Lakshmi,
Gopinathan Karumathil P.
Publication year - 2002
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2002.02825.x
Subject(s) - bombyx mori , chromatin , transcription (linguistics) , biology , transcription factor , rna polymerase iii , transfer rna , microbiology and biotechnology , dna , protein subunit , electrophoretic mobility shift assay , biochemistry , rna , polymerase , gene , rna dependent rna polymerase , linguistics , philosophy
Fractionation of nuclear extracts from posterior silk glands of mulberry silkworm Bombyx mori , resolved the transcription factor TFIIIC into two components (designated here as TFIIIC and TFIIIC1) as in HeLa cell nuclear extracts. The reconstituted transcription of tRNA genes required the presence of both components. The affinity purified TFIIIC is a heteromeric complex comprising of five subunits ranging from 44 to 240 kDa. Of these, the 51‐kDa subunit could be specifically crosslinked to the B box of . Purified swTFIIIC binds to the B box sequences with an affinity in the same range as of yTFIIIC or hTFIIIC2. Although an histone acetyl transferase (HAT) activity was associated with the TFIIIC fractions during the initial stages of purification, the HAT activity, unlike the human TFIIIC preparations, was separated at the final DNA affinity step. The tRNA transcription from DNA template was independent of HAT activity but the repressed transcription from chromatin template could be partially restored by external supplementation of the dissociated HAT activity. This is the first report on the purification and characterization of TFIIIC from insect systems.