Characterization of the Streptomyces lividans PspA response

Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium

^* To whom correspondence should be addressed. Email: Jozef.Anne{at}rega.kuleuven.be.

	Abstract

The phage shock protein (Psp) is induced by extracytoplasmic stress that may reduce the energy status of the cell. It is encoded in E. coli by the phage-shock-protein regulon consisting of pspABCDE, and by pspF and pspG. The phage-shock-protein system is highly conserved among a large number of Gram-negative bacteria. However, many bacterial genomes only contain a pspA homologue but no homologues of the other genes of the Psp system. This conservation seems to indicate that PspA alone might play an important role in these bacteria.

In Streptomyces lividans, a soil-borne Gram-positive bacterium, the phage-shock-protein system consists only of the pspA gene. In this report we showed that pspA encodes a 28 kDa protein that is present in both the cytoplasmic and the membrane fraction of S. lividans mycelium. We demonstrated that the pspA gene is strongly induced under stress conditions that attack the membrane integrity and that it is essential for growth and survival under most of these conditions.

The data reported here clearly show that PspA plays an important role in S. lividans under stress conditions, despite the absence of other psp homologues, suggesting that PspA may be more important in most bacteria than previously thought.