The Bacillus subtilis RNase P holoenzyme contains two RNase P RNA and two RNase P protein subunits.
Ribonuclease P (RNase P) catalyzes the 5' maturation of precursor tRNA transcripts and, in bacteria, is composed of a catalytic RNA and a protein. We investigated the oligomerization state and the shape of the RNA alone and the holoenzyme of Bacillus subtilis RNase P in the absence of substrate by synchrotron small-angle X-ray scattering and affinity retention. The B. subtilis RNase P RNA alone is a monomer; however, the scattering profile changes upon the addition of monovalent ions, possibly suggesting different interdomain angles. To our surprise, the X-ray scattering data combined with the affinity retention results indicate that the holoenzyme contains two RNase P RNA and two RNase P protein molecules. We propose a structural model of the holoenzyme with a symmetrical arrangement of the two RNA subunits, consistent with the X-ray scattering results. This (P RNA)2(P protein)2 complex likely binds substrate differently than the conventional (P RNA)1(P protein)1 complex; therefore, the function of the B. subtilis RNase P holoenzyme may be more diverse than previously thought. These revisions to our knowledge of the RNase P holoenzyme suggest a more versatile role for proteins in ribonucleoprotein complexes.
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA.
X W
XW
Fang
X J
XJ
Yang
K
K
Littrell
S
S
Niranjanakumari
P
P
Thiyagarajan
C A
CA
Fierke
T R
TR
Sosnick
T
T
Pan
D001360:Avidin / Q000737:chemistry; D001412:Bacillus subtilis / Q000201:enzymology*; D001710:Biotin / Q000737:chemistry; D002850:Chromatography, Gel; D004722:Endoribonucleases / Q000737:chemistry / Q000235:genetics*; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics; D008958:Models, Molecular; D012322:RNA Precursors / Q000737:chemistry / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D016337:RNA, Catalytic / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D043262:Ribonuclease P; D013379:Substrate Specificity
D020035:Holoenzymes; D012322:RNA Precursors; D012329:RNA, Bacterial; D016337:RNA, Catalytic; D001360:Avidin; D001710:Biotin; D004722:Endoribonucleases; D043262:Ribonuclease P