BORRELIA-BURGDORFERI SWIMS WITH A PLANAR WAVE-FORM SIMILAR TO THAT OFEUKARYOTIC FLAGELLA

Borrelia burgdorferi is a motile spirochete with multiple internal per iplasmic flagella (PFs) attached near each end of the cell cylinder; t hese PFs overlap in the cell center. We analyzed the shape and motion of wild type and PF-deficient mutants using both photomicrography and video microscopy. We found that swimming cells resembled the dynamic m ovements of eukaryotic flagella. In contrast to helically shaped spiro chetes, which propagate spiral waves, translating B. burgdorferi swam with a planar waveform with occasional axial twists; waves had a peak- to-peak amplitude of 0.85 mum and a wavelength of 3.19 mum. Planar wav es began full-sized at the anterior end and propagated toward the back end of the cell. Concomitantly, these waves gyrated counter-clockwise as viewed from the posterior end along the cell axis. In nontranslati ng cells, wave propagation ceased. Either the waveform of nontranslati ng cells resembled the translating form, or the cells became markedly contorted. Cells of the PF-deficient mutant isolated by Sadziene et al . [Sadziene, A., Thomas, D. D., Bundoc, V. G., Holt, S. C. & Barbour, A. G. (1991) J. Clin. Invest. 88, 82-92] were found to be relatively s traight. The results suggest that the shape of B. burgdorferi is dicta ted by interactions between the cell body and the PFs. In addition, th e PFs from opposite ends of the cell are believed to interact with one another so that during the markedly distorted nontranslational form, the PFs from opposite ends rotate in opposing directions around one an other, causing the cell to bend.