Sequencing, expression, and genetic characterization of the Helicobacter pylori ftsH gene encoding a protein homologous to members of a novel putative ATPase family

Abstract

In this study, we isolated and sequenced a Helicobacter pylori gene, designated ftsH, coding for a 632-amino-acid protein which displayed striking similarity throughout its full length to FtsH proteins identified in Escherichia coli, Lactococcus lactis, and Bacillus subtilis. H. pylori FtsH also possessed approximately 200-amino-acid region containing a putative ATPase module which is conserved among members of the AAA protein family (AAA, ATPase associated with diverse cellular activities). The H. pylori ftsH product was overexpressed in E. coli and reacted immunologically with an anti-E. coli FtsH serum (T. Tomoyasu, K. Yamanaka, K. Murata, T. Suzaki, P. Bouloc, A. Kato, H. Niki, S. Hiraga, and T. Ogura, J. Bacteriol. 175:1352-1357, 1993). FtsH was also shown to be present in the membrane fraction of H. pylori, suggesting that it is membrane bound. Disruption of the ftsH gene led to the loss of viability of H. pylori, demonstrating that this gene is essential for cell growth. Overproduction of both H. pylori FtsH and E. coli FtsH together tremendously reduced the growth rate of the E. coli host cells, whereas the growth of the E. coli cells carrying the wild-type E. coli ftsH operon on the chromosome was not significantly affected by overproduction of H. pylori FtsH itself. This result suggests that the abnormal growth of cells results from interaction between H. pylori FtsH and E. coli FtsH.