Probing for pH-regulated proteins in Sinorhizobium medicae using proteomic analysis

Wayne G. Reeve*, Ravi P. Tiwari, Nelson Guerreiro, Janine Stubbs, Michael J. Dilworth, Andrew R. Glenn, Barry G. Rolfe, Michael A. Djordjevic, John G. Howieson

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    15 Citations (Scopus)


    To elucidate the mechanisms of pH response in an acid-tolerant Sinorhizobium medicae strain we have identifi ed acid-activated gene transcription and now complement this approach by using a proteomic analysis to identify the changes that occur following exposure to acidity. Protein profi les of persistently or transiently acid-stressed S. medicae cells were compared to those grown in pH neutral, buffered media. Fifty pH-regulated proteins were identified; N-terminal sequences for 15 of these were obtained using the Edman degradation. Transient acid exposure downregulated GlnA and GlnK and upregulated a hypothetical protein. Continuing acid exposure downregulated ClpP, an ABC transporter, a hypothetical protein, a lipoprotein, the Trp-like repressor WrbA1 and upregulated DegP, fructose bisphosphate aldolase, GroES, malate dehydrogenase and two hypothetical proteins. These findings implicate proteolytic, chaperone and transport processes as key components of pH response in S. medicae .

    Original languageEnglish
    Pages (from-to)140-147
    Number of pages8
    JournalJournal of Molecular Microbiology and Biotechnology
    Issue number3
    Publication statusPublished - 2004


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