We thank Carol H. Sibley for helpful discussion and encouragement for pursing this work. We thank Sanghoon Kim for his help

at various stages of this work presented here. This study was supported by a grant to H.R. from the Kyung Hee University (KHU-20100662). “
“We characterized STY1365, a small ORF of Salmonella enterica serovar Typhi. This 174-bp ORF encodes a putative product of 57 amino acid residues with a premature stop codon. Nevertheless, bioinformatic analyses revealed that the predicted product of STY1365 has similarity to putative holin genes of Escherichia coli and bacteriophage ΦP27. STY1365 showed a high-level expression at the early log phase and a small corresponding protein product was detected mainly in CYC202 ic50 the inner membrane fraction. Anti-infection Compound Library Cloning of STY1365 in pSU19 mid-copy-vector

produced retardation in S. Typhi growth, increased cell permeability to crystal violet and altered the inner membrane protein profile. Similar results were obtained when STY1365 was induced with isopropyl-β-d-thio-galactoside in pCC1™ single-copy vector. Our results support the fact that S. Typhi STY1365 encodes a holin remnant protein that is involved in the stability of the bacterial envelope. Salmonella enterica serovars include a wide group of Gram-negative facultative microorganisms that infect a broad range of hosts, causing a variety of diseases from self-limiting gastroenteritis to severe systemic infection. Salmonella enterica serovar Typhi (S. Typhi) is a highly adapted, human-specific pathogen that causes an enteric fever known as typhoid fever, a systemic disease often characterized by high fever, malaise and abdominal pain (Parry et al., 2002). The Sitaxentan evolution of a host-restricted pathogen such as S. Typhi might have occurred by acquisition of genetic material (plasmids, phages and genomic islands), pseudogenization and/or genome degradation (Andersson & Andersson, 1999; Moran & Plague, 2004; Trombert et al., 2010). In fact, S. Typhi, compared with Salmonella Typhimurium, has a higher number

of pseudogenes and has acquired new virulence traits (Sabbagh et al., 2010). The latter is exemplified by a genomic island recently characterized by our laboratory, GICT18/1. This island is inserted within sap operon and causes loss of resistance to protamine in S. Typhi (Rodas et al., 2010). GICT18/1 encodes nine ORFs, of which some have been annotated as phage gene remnants and others as hypothetical proteins (Parkhill et al., 2001; Rodas et al., 2010). However, Faucher et al. (2006) demonstrated that some of these ORFs are transcriptionally down-/upregulated within THP-1 human macrophages, which suggests that these ORFs are indeed expressed. One of these ORFs, STY1365, has been described as a 174-bp phage pseudogene with a premature stop codon that has similarity to holins (Parkhill et al., 2001; Rodas et al., 2010).