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J. Bacteriol., Jun 1996, 3177-3187, Vol 178, No. 11
Y You, S Elmore, LL Colton, C Mackenzie, JK Stoops, GM Weinstock and SJ Norris
Treponema pallidum and other members of the genera Treponema, Spirochaeta,
and Leptonema contain multiple cytoplasmic filaments that run the length of
the organism just underneath the cytoplasmic membrane. These cytoplasmic
filaments have a ribbon-like profile and consist of a major cytoplasmic
filament protein subunit (CfpA, formerly called TpN83) with a relative
molecular weight of approximately 80,000. Degenerate DNA primers based on
N-terminal and CNBr cleavage fragment amino acid sequences of T. pallidum
subsp. pallidum (Nichols) CfpA were utilized to amplify a fragment of the
encoding gene (cfpA). A 6.8-kb EcoRI fragment containing all but the 5' end
of cfpA was identified by hybridization with the resulting PCR product and
cloned into Lambda ZAP II. The 5' region was obtained by inverse PCR, and
the complete gene sequence was determined. The cfpA sequence contained a
2,034-nucleotide coding region, a putative promoter with consensus
sequences (5'-TTTACA- 3' for -35 and 5'-TACAAT-3' for -10) similar to the
sigma70 recognition sequence of Escherichia coli and other organisms, and a
putative ribosome-binding site (5'-AGGAG-3'). The deduced amino acid
sequence of CfpA indicated a protein of 678 residues with a calculated
molecular mass of 78.5 kDa and an estimated pI of 6.15. No significant
homology to known proteins or structural motifs was found among known
prokaryotic or eukaryotic sequences. Expression of a LacZ-CfpA fusion
protein in E. coli was detrimental to survival and growth of the host
strain and resulted in the formation of short, irregular filaments
suggestive of partial self-assembly of CfpA. The cytoplasmic filaments of
T. pallidum and other spirochetes appear to represent a unique form of
prokaryotic intracytoplasmic inclusions.
Copyright © 1996, American Society for Microbiology
Characterization of the cytoplasmic filament protein gene (cfpA) of Treponema pallidum subsp. pallidum
Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston 77225, USA.
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