Differences in lysine-sRNA from spore and vegetative cells of Bacillus subtillis.

Abstract

The changes in the syntheses of macromolecules that aecompany sporulation of Bacillus subtilis have been the subject of several recent reports. In brief, the available data show that as a rapidly growing culture of B. sublilis departs from strict logarithmic growth, the net synthesis of RNA is abruptly arrested although the protein and DNA contenit approximately double after that time.' De novo RNA synthesis, however, measured by the incorporationi of labeled precursors, coiitinues throughout the stationary and sporulation phase but is just offset by a degradation of cellular RNA. The IRNA synthesized during this time appears not only in the messeniger fraction but also in soluble and ribosomal fractioiis.'-3 Despite this active turniover of soluble and ribosomal IRNA durilng sporulation, the RNA composition of B. subtilis spores appears to be only slightly different from that of vegetative cells. The ratio of soluble to ribosomal RNA increases during stationary phase, but the base compositions of these species are not signifieantly different from their counterparts in vegetative cells.4I However, Doi6 has observed an asymmetry between the elution profiles from methylated albumin kieselguhr columns of soluble RNA from vegetative cells and spores, indicating an alteration of this fraction during sporulation. In the present communication, the abilities of sRNA from spores and vegetative cells of B. subtilis to accept several amino acids are compared. Of the six amino acids tested, all but lysine were incorporated into spore sRNA to a lesser extent than into vegetative sRNA. The incorporation of lysine into sporal sRNA was more than twice that observed when vegetative sRNA was employed as an aeceptor. Comparison of the elution profiles of spore and vegetative lysyl-sRNA shows that spore sRNA contains a component not found in appreciable amounts in vegetative slRNA.