title: A global response to sulfur starvation in Pseudomonas putida and its relationship to the expression of low-sulfur-content proteins.
abstract: Sulfur is essential for life on Earth, but its availability is limited in many environments. Here the sulfur-starvation response of the model soil bacterium Pseudomonas putida KT2440 is shown to be associated with an approximately fivefold reduction in the total soluble thiol content of the cell. A bioinformatic survey of the P. putida KT2440 genome identified 646 genes encoding proteins with a significantly lower than average sulfur content (low sulfur-content proteins, LSPs), the expression of which may have a role in the global reduction of cellular thiol content during sulfur starvation. Analysis of the genetic organization of the LSP-encoding genes showed that 31% were potentially transcriptionally associated with at least one other gene encoding a protein defined as an LSP. In particular, 55 LSP genes were located in three large clusters, termed low-sulfur islands (LSIs) here. The predicted identities of the proteins encoded by the LSIs strongly suggest that the LSIs have a role in acquiring sulfur from organic sulfur sources during sulfur starvation. This hypothesis was supported by transcription fusion studies on a limited number of LSP promoters under low-sulfur conditions. In a wider survey of bacterial species, LSIs were found to be more prevalent in free-living, Gram-negative bacteria than in Gram-positive or obligately intracellular bacteria.
authors.affiliation: CSIRO, Entomology, Canberra, ACT, Australia. colin.scott@csiro.au
authors.forename: Colin
authors.initials: C
authors.lastname: Scott
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Hilton
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Coppin
authors.forename: Robyn J
authors.initials: RJ
authors.lastname: Russell
authors.forename: John G
authors.initials: JG
authors.lastname: Oakeshott
authors.forename: Tara D
authors.initials: TD
authors.lastname: Sutherland
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D016680:Genome, Bacterial; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D013438:Sulfhydryl Compounds; D013455:Sulfur