Attenuated enzootic (pestoides) isolates of Yersinia pestis express active aspartase.
It is established that Yersinia pestis, the causative agent of bubonic plague, recently evolved from enteropathogenic Yersinia pseudotuberculosis by undergoing chromosomal degeneration while acquiring two unique plasmids that facilitate tissue invasion (pPCP) and dissemination by fleabite (pMT). Thereafter, plague bacilli spread from central Asia to sylvatic foci throughout the world. These epidemic isolates exhibit a broad host range including man as opposed to enzootic (pestoides) variants that remain in ancient reservoirs where infection is limited to muroid rodents. Cells of Y. pseudotuberculosis are known to express glucose-6-phosphate dehydrogenase (Zwf) and aspartase (AspA); these activities are not detectable in epidemic Y. pestis due to missense mutations (substitution of proline for serine at amino position 155 of Zwf and leucine for valine at position 363 of AspA). In this study, functional Zwf was found in pestoides strains E, F and G but not seven other enzootic isolates; enzymic activity was associated with retention of serine at amino acid position 155. Essentially, full AspA activity occurred in pestoides isolates where valine (pestoides A, B, C and D) or serine (pestoides E, F, G and I) occupied position 363. Reduced activity occurred in strains Angola and A16, which contained phenylalanine at this position. The kcat but not Km of purified AspA from strain Angola was significantly reduced. In this context, aspA of the recently described attenuated enzootic microtus biovar encodes active valine at position 363, further indicating that functional AspA is a biomarker for avirulence of Y. pestis in man.
Bearden
Scott W
SW
Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases, Bacterial Diseases Branch, Fort Collins, CO 80521, USA.
Sexton
Christopher
C
Centers for Disease Control and Prevention, Division of Vector-Borne Infectious Diseases, Bacterial Diseases Branch, Fort Collins, CO 80521, USA.
Pare
Joshua
J
Department of Microbiology and Molecular Genetics, Michigan State University, 2215 Biomedical Physical Sciences, East Lansing, MI 48824, USA.
Fowler
Janet M
JM
Department of Microbiology and Molecular Genetics, Michigan State University, 2215 Biomedical Physical Sciences, East Lansing, MI 48824, USA.
Arvidson
Cindy G
CG
Department of Microbiology and Molecular Genetics, Michigan State University, 2215 Biomedical Physical Sciences, East Lansing, MI 48824, USA.
Yerman
Lyudmyla
L
Department of Chemistry, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, USA.
Viola
Ronald E
RE
Department of Chemistry, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, USA.
Brubaker
Robert R
RR
Department of Microbiology, The University of Chicago, 920 E. 58th Street, Chicago, IL 60637, USA.
D000818:Animals; D001220:Aspartate Ammonia-Lyase / Q000235:genetics* / Q000378:metabolism*; D004196:Disease Outbreaks; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D010930:Plague / Q000453:epidemiology / Q000382:microbiology; D012376:Rodent Diseases / Q000382:microbiology; D012377:Rodentia / Q000382:microbiology*; D014774:Virulence; D015009:Yersinia Infections / Q000382:microbiology / Q000662:veterinary; D015010:Yersinia pestis / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification / Q000472:pathogenicity*; D015011:Yersinia pseudotuberculosis / Q000201:enzymology
D005954:Glucosephosphate Dehydrogenase; D001220:Aspartate Ammonia-Lyase