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J. Bacteriol., Jun 1995, 3556-3562, Vol 177, No. 12
DR Blanco, CI Champion, MM Exner, H Erdjument-Bromage, RE Hancock, P Tempst, JN Miller and MA Lovett
We have recently reported the isolation and purification of the Treponema
pallidum outer membrane and the identification of its rare protein
constituents, including a 31-kDa protein markedly enriched in the outer
membrane preparation (D.R. Blanco, K. Reimann, J. Skare, C.I. Champion, D.
Foley, M. M. Exner, R. E. W. Hancock, J. N. Miller, and M. A. Lovett, J.
Bacteriol. 176:6088-6099, 1994). In this study, we report the cloning,
sequencing, and expression of the structural gene which encodes the 31-kDa
outer membrane protein, designated Tromp1. The deduced amino acid sequence
from the tromp1 gene sequence encodes a 318- amino-acid polypeptide with a
putative 40-amino-acid signal peptide. Processing of Tromp1 results in a
mature protein with a predicted molecular mass of 30,415 Da and a
calculated pI of 6.6. Secondary- structure predictions identified repeated
stretches of amphipathic beta- sheets typical of outer membrane protein
membrane-spanning sequences. A topological model of Tromp1 containing 14
transmembrane segments is proposed. Specific antiserum against a
recombinant Tromp1 fusion protein was generated and was used to identify
native Tromp1 in cellular fractionation. Upon Triton X-114 extraction and
phase separation of T. pallidum, the 31-kDa Tromp1 protein was detected in
the detergent-phase fraction but not in the protoplasmic cylinder or
aqueousphase fractions, consistent with a hydrophobic outer membrane
protein. Anti-Tromp1 antiserum was also used to identify native Tromp1
purified from whole T. pallidum by Triton X-100 solubilization followed by
nondenaturing isoelectric focusing.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Porin activity and sequence analysis of a 31-kilodalton Treponema pallidum subsp. pallidum rare outer membrane protein (Tromp1)
Department of Microbiology and Immunology, School of Medicine, University of California at Los Angeles 90024, USA.
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