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Molecular characterization and cellular localization of TpLRR, a processed leucine-rich repeat protein of Treponema pallidum, the syphilis spirochete.

Abstract
Automated Edman degradation was used to obtain N-terminal and internal amino acid sequences from a 26-kDa protein in isolated Treponema pallidum outer membranes (OMs). The resulting sequences enabled us to PCR amplify from T. pallidum DNA a 275-bp fragment of the corresponding gene. The complete nucleotide sequence of the gene was determined from fragments amplified by long-distance PCR. Primer extension verified the assigned translational start of the open reading frame (ORF) and putative upstream promoter elements. The ORF encoded a highly basic (pI 9.6) 26-kDa protein which contained an N-terminal 25-amino-acid leader peptide terminated by a signal peptidase I cleavage site. The mature protein contained seven tandemly spaced copies (as well as an eighth incomplete copy) of a leucine-rich repeat (LRR), a motif previously identified in a number of prokaryotic and eukaryotic proteins. Accordingly, the polypeptide was designated T. pallidum leucine-rich repeat protein (TpLRR). Although Triton X-114 phase partitioning showed that TpLRR was hydrophilic, cell localization studies showed that most of the antigen was associated with the peptidoglycan-cytoplasmic membrane complex rather than being freely soluble in the periplasmic space. Immunoblot studies showed that syphilis patients develop a weak antibody response to the antigen. Lastly, the lrr(T. pallidum) gene was mapped to a 60-kb SfiI-SpeI fragment of the T. pallidum chromosome which also contains the rrnA and flaA genes. The function(s) of TpLRR is currently unknown; however, protein-protein and/or protein-lipid interactions mediated by its LRR motifs may facilitate interactions between components of the T. pallidum cell envelope.
AuthorsD V Shevchenko, D R Akins, E Robinson, M Li, T G Popova, D L Cox, J D Radolf
JournalJournal of bacteriology (J Bacteriol) Vol. 179 Issue 10 Pg. 3188-95 (May 1997) ISSN: 0021-9193 [Print] United States
PMID9150213 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Antibodies, Bacterial
  • Bacterial Outer Membrane Proteins
  • Peptidoglycan
  • TpLRR protein, Treponema pallidum
  • Leucine
Topics
  • Amino Acid Sequence
  • Antibodies, Bacterial (biosynthesis)
  • Bacterial Outer Membrane Proteins (chemistry, genetics, isolation & purification)
  • Base Sequence
  • Cell Membrane (chemistry, genetics)
  • Chromosome Mapping
  • Cytoplasm (chemistry)
  • Leucine (metabolism)
  • Molecular Sequence Data
  • Peptidoglycan (chemistry)
  • Protein Structure, Secondary
  • Repetitive Sequences, Nucleic Acid
  • Syphilis (microbiology)
  • Treponema pallidum (chemistry, genetics)

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