The major sheath protein-encoding gene (mspA) of the oral spirochete Trepon
ema maltophilum ATCC 51939(T) was cloned by screening a genomic library wit
h an anti-outer membrane fraction antibody. The mspA gene encodes a precurs
or protein of 575 amino acids with a predicted molecular mass of 62.3 kDa,
including a signal peptide of 19 amino acids. The native MspA formed a heat
modifiable, detergent- and trypsin-stable complex which is associated with
the outer membrane. Hybridization with an mspA-specific probe showed no cr
ossreactivity with the msp gene from Treponema denticola.