Agricultural Microbes Genome 2 Conference

Session: Technology & Bioinformatics
S02_02.html

FROM PROTEOME TO TRANSCRIPT - MOLECULAR ANALYSIS OF SULFATE STARVATION IN SOIL BACTERIA

¹ School of Biological Sciences, University of Manchester, Oxford Rd, Manchester, M13 9PT, United Kingdom.

² Institute of Biochemistry, University of Lausanne, Ch. des Boveresses 155, Epalinges, 1066 Switzerland.

³ Wallenberg Laboratory, Lund University, P.O.Box 7031, Lund, 220 07, Sweden.

Pseudomonas aeruginosa is a versatile Gram-negative species that grows in soils and sediments, as well as being a pathogen of plants and humans. It was the first Pseudomonas species to be targeted for genome sequencing (http://www.pseudomonas.com/, http://pseudomonas.bit.uq.edu.au) and the results are therefore paradigmatic for other Pseudomonas species involved in soil processes and plant protection. We analyzed the response of P. aeruginosa to starvation for sulfate, using differential two-dimensional PAGE to identify thirteen proteins that were differentially upregulated during growth in the absence of inorganic sulfate. The protein spots were excised from the gels and analysed by Edman N-terminal sequencing and MS sequencing (MS/MS). The genes encoding eleven of these proteins could be unambiguously identified in the P. aeruginosa genome sequence. Reverse-transcription PCR (RT-PCR) was then used to investigate the expression of these genes, confirming that their repression in the presence of sulfate was occurring at a transcriptional level. Many of the sulfate-regulated genes identified were found in larger putative transcriptional units, together with other genes. The use of RT-PCR facilitated a rapid analysis of the transcriptional regulation of these further genes, and a number of additional sulfate-starvation-induced genes were identified. The study demonstrates the power of a combined proteomic/genomic/transcriptional analysis approach for investigation of the responses of an organism to an environmental stimulus.