The Absence of FtsH Metalloprotease Activity Causes Overexpression of the σ ^W -Controlled pbpE Gene, Resulting in Filamentous Growth of Bacillus subtilis

Abstract

FtsH is a membrane-bound and energy-dependent metalloprotease in bacteria which is involved in the posttranslational control of the activity of a variety of important transcription factors and in the degradation of uncomplexed integral membrane proteins. For Bacillus subtilis, little is known about the target proteins of FtsH protease. Its gene is not essential, but knockout strains display a pleiotropic phenotype including sensitivity toward salt and heat stress, defects in sporulation and competence, and largely filamentous growth. Comparison of the intracellular proteomes of wild-type and ftsH knockout strains revealed that at least nine proteins accumulated in the absence of ftsH, four of which could be identified. Two of these proteins turned out to be members of the W regulon. Accumulation of one of these W -controlled proteins, the penicillin-binding protein PBP4*, was analyzed in more detail. We could show that PBP4* is not a proteolytic substrate of FtsH and that its overproduction is due to the enhanced transcription of its gene (pbpE) in ftsH null mutants. The filamentous growth phenotype of ⌬ftsH strains was abolished in a ⌬ftsH ⌬pbpE double knockout. In ftsH wild-type strains with the pbpE gene under regulatable control, pbpE overexpression caused filamentation of the cells. DNA macroarray analysis revealed that most genes of the W regulon are transcribed at elevated levels in an ftsH mutant. The influence of FtsH on W -controlled genes is discussed.FtsH belongs to the AAA (ATPases associated with diverse cellular activities) protein superfamily, and members of this family are involved in a wide variety of cellular processes, such as vesicle-mediated protein transport, cell cycle control, control of gene expression, and proteolysis (for recent reviews, see references 19 and 35). The AAA proteins constitute a subfamily of the Walker-type nucleoside triphosphatases and contain conserved ATPase domains, typically spanning 200 to 250 residues, referred to as AAA modules (6,20). FtsH is a member of the AAA proteases, which occur in eubacteria and eukaryotic organelles such as mitochondria and chloroplasts, but not in archaea, and contain an AAA module and a zinc metalloprotease domain in a single polypeptide chain. Bacterial FtsH proteins are anchored via two transmembrane segments in the cytoplasmic membrane, with the short N-and the long Cterminal parts facing the cytoplasm. These metalloproteases are involved in the quality control of membrane-bound proteins and in the degradation of short-lived cytoplasmic regulatory proteins (for recent reviews, see references 16 and 26).While several target proteins of the Escherichia coli FtsH metalloprotease have already been identified, they remained elusive in Bacillus subtilis. Therefore, we reasoned that comparing the proteomes of B. subtilis wild-type and ftsH knockout cells should reveal target proteins accumulating in the absence of the protease. It should be mentioned that, in contrast to that of E. coli, the B. subtilis ftsH gene is dispensable, though i...

Role of the hprT–ftsH locus in Staphylococcus aureus

“…How FtsH exerts its effects at the molecular level is still largely unknown in any organism. Mutation of ftsH has been shown to cause changes in gene expression in E. coli and B. subtilis (Tomoyasu et al, 1993;Zellmeier et al, 2003) and FtsH is involved in the degradation of regulatory components in E. coli (Herman et al, 1995;Tomoyasu et al, 1995). Another function of FtsH may be to prevent the accumulation of damaged proteins, which would otherwise lead to defects under stressful conditions.…”

Lack of the host membrane protease FtsH hinders release of the Lactococcus lactis bacteriophage TP712

“…altered peptidoglycan structure) that impair phage lysis. FtsH has been involved in the transcriptional regulation of pbpE, encoding the D,Dendopeptidase PBP4* in Bacillus subtilis (Zellmeier et al, 2003). Upregulation of pbpE makes Bacillus peptidoglycan less susceptible to mutanolysin (Palomino et al, 2009).…”

Genomic organization and in vivo characterization of proteolytic activity of FtsH of Mycobacterium smegmatis SN2

“…Further, a 26 amino acid peptide, SpoVM, which is essential for spore formation, was found to be a substrate for FtsH . The absence of FtsH protease has been found to result in the overexpression of s W -controlled genes in B. subtilis, although the reason for it is unknown (Zellmeier et al, 2003). FtsH protease has also been shown to participate in membrane biogenesis by regulating the levels of UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase [the lpxC(envA) gene product] involved at the committed step in the biosynthesis of lipid A .…”