Systematic identification of selective essential genes in Helicobacter pylori by genome prioritization and allelic replacement mutagenesis

A comparative genomic approach was used to identify Helicobacter pylori 26695 open reading frames (ORFs) which are conserved in H. pylori J99 but highly diverged in other eubacteria. A survey of selected pathways of central intermediary metabolism was also carried out, and genes with a potentially selective role in H. pylori were identified. Forty-five ORFs identified in these two analyses were screened using a rapid vector-free allelic replacement mutagenesis technique, and 33 were shown to be essential in vitro. Notably, 13 ORFs gave essentiality results which are unexpected in view of their known, or proposed functions, and phylogenetic analysis was used to investigate the annotation of 7 such ORFs which are highly diverged. We propose that the products of a number of these H. pylori-specific essential genes may be suitable targets for novel anti-H. pylori therapies.