title: Multiple Posttranslational Modifications of Leptospira biflexa Proteins as Revealed by Proteomic Analysis.
abstract: The saprophyte Leptospira biflexa is an excellent model for studying the physiology of the medically important Leptospira genus, the pathogenic members of which are more recalcitrant to genetic manipulation and have significantly slower in vitro growth. However, relatively little is known regarding the proteome of L. biflexa, limiting its utility as a model for some studies. Therefore, we have generated a proteomic map of both soluble and membrane-associated proteins of L. biflexa during exponential growth and in stationary phase. Using these data, we identified abundantly produced proteins in each cellular fraction and quantified the transcript levels from a subset of these genes using quantitative reverse transcription-PCR (RT-PCR). These proteins should prove useful as cellular markers and as controls for gene expression studies. We also observed a significant number of L. biflexa membrane-associated proteins with multiple isoforms, each having unique isoelectric focusing points. L. biflexa cell lysates were examined for several posttranslational modifications suggested by the protein patterns. Methylation and acetylation of lysine residues were predominately observed in the proteins of the membrane-associated fraction, while phosphorylation was detected mainly among soluble proteins. These three posttranslational modification systems appear to be conserved between the free-living species L. biflexa and the pathogenic species Leptospira interrogans, suggesting an important physiological advantage despite the varied life cycles of the different species.
authors.affiliation: Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA pestewart@niaid.nih.gov.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Stewart
authors.affiliation: Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Carroll
authors.affiliation: Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Twinbrook I Facility, Rockville, Maryland, USA.
authors.forename: L Rennee
authors.initials: LR
authors.lastname: Olano
authors.affiliation: Genomics Unit Research Technologies Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Sturdevant
authors.affiliation: Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Rosa
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D020869:Gene Expression Profiling; D007919:Leptospira / Q000378:metabolism / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D020543:Proteome / Q000032:analysis*; D040901:Proteomics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001426:Bacterial Proteins; D020543:Proteome