A global response to sulfur starvation in Pseudomonas putida and its relationship to the expression of low-sulfur-content proteins.
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.
Scott
Colin
C
CSIRO, Entomology, Canberra, ACT, Australia. colin.scott@csiro.au
Hilton
Margaret E
ME
Coppin
Christopher W
CW
Russell
Robyn J
RJ
Oakeshott
John G
JG
Sutherland
Tara D
TD
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*
D001426:Bacterial Proteins; D013438:Sulfhydryl Compounds; D013455:Sulfur