Insight into the virulence of Rickettsia prowazekii by proteomic analysis and comparison with an avirulent strain.
Rickettsia prowazekii, an obligate intracellular Gram-negative bacterium, is the etiologic agent of epidemic typhus. We analyzed the proteome of the virulent Breinl strain of R. prowazekii purified from infected egg yolk sacs. Total proteins from purified R. prowazekii Breinl strain were reduced by dithiothreitol, alkylated by iodoacetic acid and digested with trypsin followed by analysis with an integrated two-dimensional liquid chromatography and mass spectrometry system (2D-LC/MS/MS). A comparison was made using previously analyzed proteome of the Madrid E strain and current analysis of the Breinl strain. For Breinl 251 proteins were identified, representing 30% of the total protein-encoding genes, using a shotgun 2D-LC/MS/MS proteomic approach. This result is identical to that of Madrid E strain. Among the identified proteins, 33 from Breinl and 37 from Madrid E have an unknown function. A methyltransferase, RP028/RP027, whose gene is mutated in the avirulent Madrid E strain but not in the virulent Breinl strain, was only detectable in the Breinl strain, consistent with the genetic mutation in Madrid E. This result suggests the possible relationship between this gene product and the virulence of the strains.
Chao
Chien-Chung
CC
Viral and Rickettsial Diseases Department Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD 20910, USA. chaoc@nmrc.navy.mil
Chelius
Dirk
D
Zhang
Terry
T
Mutumanje
Elissa
E
Ching
Wei-Mei
WM
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D040081:Protein Array Analysis; D040901:Proteomics; D012283:Rickettsia prowazekii / Q000737:chemistry / Q000145:classification / Q000378:metabolism* / Q000472:pathogenicity*; D012290:Rickettsial Vaccines / Q000235:genetics / Q000276:immunology; D053719:Tandem Mass Spectrometry; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology; D014774:Virulence / Q000502:physiology
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012290:Rickettsial Vaccines; D019444:Vaccines, DNA