Signal Processing in Bacterial Chemotaxis

<p>This study localized 1) the site of ATP utilization in the signal transduction pathway of bacterial chemotaxis and 2) the point of convergence of the methylation-independent systems of chemotaxis with the methylation-dependent system. The site of ATP utilization was localized at the CheY protein/switch point. In an Eaeheriehia call strain (BT3077) containing the cheY, motor and switch genes, ATP depletion, accomplished by treating the cells with arsenate, suppressed the CheY protein-induced tumbling. ATP was not required by the switch for directing the clockwise and counterclockwise rotations of the flagellar motor. ATP did not appear to be required for normal steady-state and stimulus-altered protein methylesterase activity. Changes observed in the activity of the protein methylesterase with ATP depletion were probably secondary to changes in another chemotactic process. The CheA, the CheW and, perhaps, the CheZ protein probably do not require ATP for regulating the protein methylesterase. Three E. call hisE mutants, which are able to reduce their intracellular ATP levels to the same degree as Ealmonella iyphimutium ST23 (his111/16) when grown in minimal media without histidine, were identified. S. typhimutimm strains containing the hisE mutation and harboring ColEl-derived plasmids were shown to be incapable of reducing intracellular ATP sufficiently when grown in minimal media without histidine. The point of convergence of the methylation-independent systems of chemotaxis, aerotaxis (taxis to oxygen) and PTS chemotaxis (chemotaxis to sugars transported by the phosphoenolpyruvate-energized phosphotransferase system (PTS1), with the methylationdependent system was localized to the CheA and the CheW proteins. A strain (E. Con HCB525) containing the cheA, cheW, cheY, motor and switch genes demonstrated PTS chemotaxis. Aerotaxis was demonstrated in a strain (E. =Ai HCB513) that contained the cha gene in addition to the cheA, cheti, cheY, motor and switch genes. Strains containing only the cheY gene (E. coli HCB465) or the eheA and cheW genes (E. =al HC3349) along with the motor and switch genes did not show aerotaxis or PTS taxis. Models are presented to explain the mechanism of chemotaxis to oxygen, the PTS sugars and those chemicals and physical stimuli mediated by the methylation-dependent system of chemotaxis.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biochemistry

Year

1987

Author dc:creator

• Smith, Jimmie Marquette

Contributors dc:contributor

• Barry L. Taylor
• E. Clifford Herrmann
• Jun-ichi Ryu
• Junichi Shioi
• R. Bruce Wilcox

• Biochemistry
• Physiology
• Chemotaxis; Adenosine Triphosphate; Bacteria -- physiology

Statement dc:rights

• This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Language dc:language

English

Repository record dc:identifier

https://scholarsrepository.llu.edu/etd/942

OAI identifier oai:identifier

oai:scholarsrepository.llu.edu:etd-1887