Previous Article | Next Article ![]()
Molecular and Cellular Biology, December 2005, p. 10352-10364, Vol. 25, No. 23
0270-7306/05/$08.00+0 doi:10.1128/MCB.25.23.10352-10364.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Departments of Molecular Biophysics and Biochemistry,1 Genetics,2 Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 065203
Received 19 April 2005/ Returned for modification 25 May 2005/ Accepted 13 September 2005
One of the proteins identified as being involved in ribosome biogenesis by high-throughput studies, a putative P-loop-type kinase termed Fap7 (YDL166c), was shown to be required for the conversion of 20S pre-rRNA to 18S rRNA. However, the mechanism underlying this function has remained unclear. Here we demonstrate that Fap7 is strictly required for cleavage of the 20S pre-rRNA at site D in the cytoplasm. Genetic depletion of Fap7 causes accumulation of only the 20S pre-rRNA, which could be detected not only in 43S preribosomes but also in 80S-sized complexes. Fap7 is not a structural component of 43S preribosomes but likely transiently interacts with them by directly binding to Rps14, a ribosomal protein that is found near the 3' end of the 18S rRNA. Consistent with an NTPase activity, conserved residues predicted to be required for nucleoside triphosphate (NTP) hydrolysis are essential for Fap7 function in vivo. We propose that Fap7 mediates cleavage of the 20S pre-rRNA at site D by directly interacting with Rps14 and speculate that it is an enzyme that functions as an NTP-dependent molecular switch in 18S rRNA maturation.
Supplemental material for this article may be found at http://mcb.asm.org/.
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»