Xiufeng. Wan

Publications (2)1.82 Total impact

• Source

  Available from: usda.gov

  Article: Identification and initial characterization of a putative Mycoplasma gallinarum leucine aminopeptidase gene.

  Xiufeng Wan, Scott L Branton, Larry A Hanson, Gregory T Pharr
  [show abstract] [hide abstract]
  ABSTRACT: Aminopeptidases (APN) may play a role in host colonization of M. gallinarum. Characterization of endogenous APN activity suggests that the leucine APN (LAP) of M. gallinarum is a metallo-aminopeptidase activated by Mn2+ and is present in the cytosol and possibly associated with the inner leaflet of the membrane. A 1.36-kb open reading frame (ORF) identified from overlapping genomic phage clones showed 68% nucleotide identity and 51% amino acid identity with the M. salivarium LAP gene. This ORF is expressed as a 1.5-kb monocistronic transcript and is present as a single copy in M. gallinarum. This gene sequence was modified to account for codon usage, and expression in E. coli produced a 51-kDa protein, which compares well with the product predicted from the ORF. This ORF is a strong candidate for contributing the LAP activity of M. gallinarum protein extracts.
  Current Microbiology 02/2004; 48(1):32-8. · 1.82 Impact Factor
• Article: An aminopeptidase acting as a potential factor in host adaptation of Mycoplasma gallinarum [electronic resource] /

  Xiufeng. Wan
  [show abstract] [hide abstract]
  ABSTRACT: Unlike most other host-specific mycoplasmas, Mycoplasma gallinarum exists as a commensal with a host range including most poultry as well as some mammals. This property of M. gallinarum may reflect unique mechanisms for its colonization and persistence in hosts. Whereas M. gallinarum shows leucine and arginine aminopeptidase activity, the genes encoding the enzymes had not been cloned and characterized. We identified an aminopeptidase gene (APN) by oligonucleotide hybridization to a genomic library of M. gallinarum in lambda ZAPII bacteriophage. Nucleotide sequence analysis of overlapping phage clones identified a 1,362 bp open reading frame (ORF) encoding a putative leucine aminopeptidase gene. Database searches indicate that this ORF has 68% nucleotide identity and 51% amino acid identity with the M. salivarium leucine aminopeptidase gene. The active sites of the leucine aminopeptidases in other eukaryotes and prokaryotes were conserved in the cloned aminopeptidase gene. Northern-blot hybridization analysis showed that this ORF is expressed as a 1.5 kb transcript. Southern-blot hybridization analysis demonstrated this gene was present as a single copy in M. gallinarum. Characterization of the leucine aminopeptidase demonstrated that it is a metallo-aminopeptidase (EC 3.4.11.1) and is located in the cytoplasm with a weak interaction with the cell membrane. The subcellular location was further confirmed by immunoblotting with polyclonal anti-recombinant APN serum and M. gallinarum Triton-114 partitions. Immunoblotting results with sera from three chickens experimentally infected with M. gallinarum showed that there were very few proteins in M. gallinarum exposed to the host immune responses and that leucine aminopeptidase was not able to stimulate production of specific humoral antibody. Our results suggest that this leucine aminopeptidase play a role in nutrition supply for the host adaptation of M. gallinarum and that the enzyme was not strongly immunogenic. Mode of access: Internet via the World Wide Web. System requirements: Internet connectivity; World Wide Web browser software; Adobe Acrobat Reader. Title from title screen. Electronic book in PDF(2 files). Thesis (Ph. D.)--Mississippi State University. Department of Veterinary Medicine. Includes bibliographical references.