Previous Article | Next Article ![]()
Molecular and Cellular Biology, July 2001, p. 4453-4459, Vol. 21, No. 14
Molecular Biology Institute and Department of
Microbiology, Immunology, and Molecular Genetics, University of
California, Los Angeles, California 90095-1570
Received 16 March 2001/Accepted 20 April 2001
The Crithidia fasciculata cycling sequence binding
protein (CSBP) binds with high specificity to sequence elements in
several mRNAs that accumulate periodically during the cell cycle.
Mutations in these sequence elements abolish both cycling of the mRNA
and binding of CSBP. Two genes, CSBPA and
CSBPB, encoding putative subunits of CSBP have been
cloned and were found to be present in tandem on the same DNA molecule
and to be closely related. CSBPA and
CSBPB are predicted to encode proteins with sizes of 35.6 and 42.0 kDa, respectively. Both CSBPA and CSBPB proteins have a
predicted coiled-coil domain near the N terminus and a novel histidine
and cysteine motif near the C terminus. The latter motif is conserved
in other trypanosomatid species. Gel sieving chromatography and
glycerol gradient sedimentation results indicate that CSBP has a
molecular mass in excess of 200 kDa and an extended structure.
Recombinant CSBPA and CSBPB also bind specifically to the cycling
sequence and together can be reconstituted to give an RNA gel shift
similar to that of purified CSBP. Proteins in cell extracts bind to an
RNA probe containing six copies of the cycling sequence. The
RNA-protein complexes contain both CSBPA and CSBPB, and the binding
activity cycles in near synchrony with target mRNA levels.
CSBPA and CSBPB mRNA and protein levels
show little variation throughout the cell cycle, suggesting that
additional factors are involved in the cyclic binding to the cycling
sequence elements.
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.14.4453-4459.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Characterization of the Crithidia
fasciculata mRNA Cycling Sequence Binding
Proteins
*
Corresponding author. Mailing address: Molecular
Biology Institute, University of California, 405 Hilgard Ave., Los
Angeles, CA 90095-1570. Phone: (310) 825-4178. Fax: (310) 206-7286. E-mail: danray{at}mbi.ucla.edu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»