title: Acidic pH induced STM1485 gene is essential for intracellular replication of Salmonella.
abstract: During the course of infection, Salmonella has to face several potentially lethal environmental conditions, one such being acidic pH. The ability to sense and respond to the acidic pH is crucial for the survival and replication of Salmonella. The physiological role of one gene (STM1485) involved in this response, which is upregulated inside the host cells (by 90- to 113-fold) is functionally characterized in Salmonella pathogenesis. In vitro, the ΔSTM1485 neither exhibited any growth defect at pH 4.5 nor any difference in the acid tolerance response. The ΔSTM1485 was compromised in its capacity to proliferate inside the host cells and complementation with STM1485 gene restored its virulence. We further demonstrate that the surface translocation of Salmonella pathogenicity island-2 (SPI-2) encoded translocon proteins, SseB and SseD were reduced in the ΔSTM1485. The increase in co-localization of this mutant with lysosomes was also observed. In addition, the ΔSTM1485 displayed significantly reduced competitive indices (CI) in spleen, liver and mesenteric lymph nodes in murine typhoid model when infected by intra-gastric route. Based on these results, we conclude that the acidic pH induced STM1485 gene is essential for intracellular replication of Salmonella.
authors.affiliation: Department of Microbiology, Centre for Infectious Disease Research and Biosafety Laboratories, Indian Institute of Science, Bangalore, India.
authors.forename: Uday Sankar
authors.initials: US
authors.lastname: Allam
authors.forename: M Gopala
authors.initials: MG
authors.lastname: Krishna
authors.forename: Minakshi
authors.initials: M
authors.lastname: Sen
authors.forename: Rony
authors.initials: R
authors.lastname: Thomas
authors.forename: Amit
authors.initials: A
authors.lastname: Lahiri
authors.forename: Divya Prakash
authors.initials: DP
authors.lastname: Gnanadhas
authors.forename: Dipshikha
authors.initials: D
authors.lastname: Chakravortty
mesh_terms: D000818:Animals; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D002264:Carboxylic Acids / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D003593:Cytoplasm / Q000737:chemistry / Q000382:microbiology*; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000382:microbiology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005816:Genetic Complementation Test; D006801:Humans; D008099:Liver / Q000382:microbiology; D008198:Lymph Nodes / Q000382:microbiology; D008247:Lysosomes / Q000382:microbiology; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D050296:Microbial Viability / Q000187:drug effects; D010284:Paratyphoid Fever / Q000382:microbiology / Q000473:pathology; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D013154:Spleen / Q000382:microbiology; D013312:Stress, Physiological; D015854:Up-Regulation; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D002264:Carboxylic Acids; D037521:Virulence Factors