Competence for genetic transformation in pneumococcus depends on synthesis of a small set of proteins

Abstract

In bacterial genetic transformation the uptake of DNA and its integration into the resident chromosome is dependent on a special cellular state, termed competence. In those species where appearance of competence has been studied, specific (but often poorly defined) growth conditions lead to a simultaneous development of competence in a substantial fraction of the cells in a culture. In Bacillus subtilis^1–4, and in Haemophilus species^5,6, competence appears in the stationary phase of growth or in certain other growth-limiting conditions^5,6. Streptococcus pneumoniae (pneumococcus) is perhaps unusual in that virtually all cells of a culture become competent^7,8, for a short period at a specific cell density during logarithmic growth, without perturbing the growth rate⁹. The synchronous appearance of competence in pneumococcal cultures results from an auto-catalytic effect of a small protein¹⁰ released by the cells that induces competence^11,12. The response to competence factor has been shown to require protein synthesis¹³. We report here additional information on the nature of competence in pneumococcus: pulse-labelling studies show that for the brief period of competence protein synthesis is restricted to a few specific polypeptides.