Numerical simulation of continuous miner rock cutting process [electronic resource] /
Periplasmic Flagella of the Spirochetes Borrelia burgdorferi and Brachyspira
Melanie S. Sal
Spirochetes are unique bacteria that cause a variety of diseases. Motility,
provided by periplasmic flagella (PFs), is a virulence factor for spirochetes. This
work focuses on PFs from Borrelia burgdorferi and Brachyspira hyodysenteriae.
PFs consist of three main parts: basal body, hook, and filament. Monoclonal
antibodies were developed to attempt identification of individual FlaB filament
proteins in B. hyodysenteriae.
The PF filament of B. burgdorferi consists of a major flagellin, FlaB, and a
minor flagellin, FlaA. FlaB constitutes 10-14%, whereas FlaA contributes less
than 0.5%, of total cellular protein. Although these flagellins co-precipitate, the
location of FlaA on a PF is unknown. FlaA accumulates at only 13% of wild type
levels in the flaB null mutant, MC-1. Because mRNA levels are not negatively
altered, FlaA regulation occurs at a posttranscriptional level. As FlaA is
degraded over time, protein turnover may be a mechanism responsible for
reduced FlaA accumulation in MC-1.
The flagellar hook has structural and regulatory roles in many bacteria.
The PF hook gene, flgE, is required for motility, wave-like cell morphology, and
PF synthesis in B. burgdorferi. The flgE null mutant, SC-1, has markedly
reduced levels of filament proteins FlaB and FlaA. Because flaB and flaA
transcripts are not negatively altered, filament protein synthesis is regulated at a
posttranscriptional level. As seen in MC-1, FlaA is degraded over time in SC-1.
Conversely, FlaB is stable indicating that protein turnover is not a significant
mechanism for maintaining reduced FlaB accumulation in SC-1.
In addition to a loss of FlgE in SC-1, a series of high molecular weight
bands reactive to hook antisera was lost. This “ladder” was present in wild type
strains B31 and N40, and also in MC-1 cells, all of which presumably assemble
the PF hook. The ladder is absent in SC-1 and fliF null basal body mutants in
which the PF hook cannot assemble. Furthermore, the ladder is present in
purified PFs and in isolated hook-basal body complexes from B31 PFs. The
ladder suggests that these bands are FlgE aggregates that are strongly
associated, perhaps by cross-linking. The nature of FlgE protein association is
School:West Virginia University
School Location:USA - West Virginia
Source Type:Master's Thesis
Keywords:rock mechanics bits drilling and boring finite element method
Date of Publication: