Life Sciences Commons^™

Mxin Differentially Regulates Monomeric And Oligomeric Species Of The Shigella Type Three Secretion System Atpase Spa47, Heather B. Case, Nicholas E. Dickenson

Chemistry and Biochemistry Faculty Publications

Shigella rely entirely on the action of a single type three secretion system (T3SS) to support cellular invasion of colonic epithelial cells and to circumvent host immune responses. The ATPase Spa47 resides at the base of the Shigella needle-like type three secretion apparatus (T3SA), supporting protein secretion through the apparatus and providing a likely means for native virulence regulation by Shigella and a much needed target for non-antibiotic therapeutics to treat Shigella infections. Here, we show that MxiN is a differential regulator of Spa47 and that its regulatory impact is determined by the oligomeric state of the Spa47 ATPase, with …

Spa47 Is An Oligomerization - Activated Type Three Secretion System (T3ss) Atpase From Shigella Flexneri, Jamie Lee Kingsford

Undergraduate Honors Capstone Projects

Gram-negative pathogens often use conserved type three secretion systems (T3SS) for virulence. The Shigella type three secretion apparatus (T3SA) penetrates the host cell membrane and provides a unidirectional conduit for injection of effectors into host cells. The protein Spa4 7 localizes to the base of the apparatus and is speculated to be an ATPase that provides the energy for T3SA formation and secretion. Here, we developed an expression and purification protocol, producing active Spa47 and providing the first direct evidence that Spa47 is a bona fide ATPase. Additionally, size exclusion chromatography and analytical ultracentrifugation identified multiple oligomeric species of Spa47 …

Theory Of Active Transport Across Frog Skin And Other Bifacial Cell Systems: A Subsidiary Of The Association-Induction Hypothesis, Gilbert N. Ling

Scanning Microscopy

This review presents the theory of solute transport across frog skin, epithelial cells of the intestine, the kidney tubules, and other similar systems. This theory is a part of a broader theory of the living cell, called the association-induction hypothesis.

The central pumping mechanism is the cyclic activity of a sponge-like cytoplasmic protein(s), which alternately sop-up (by adsorption) the solute being transported and squeeze it out again (by desorption) into the cytoplasmic water at a high concentration level. The uptake phase begins with the adsorption of ATP on key cardinal sites of the protein involved; the release phase is triggered …

The Use Of Backscattered Electron Imaging, X-Ray Microanalysis And X-Ray Microscopy In Demonstrating Physiological Cell Death, I. D. Bowen, N. A. Worrill, C. A. Winters, K. Mullarkey

Scanning Microscopy

The cytochemical localization of enzymatic activity by means of backscattered electron imaging (BEi) is reviewed and the application of BEI to changes in acid phosphatase and ATPase distribution during physiological (programmed) cell death in Heliothis midgut is explored. Programmed cell death entails the release of nascent free acid phosphatase as extracisternal hydrolase. This shift can readily be detected by means of the atomic number contrast imparted by BEI of the lead phosphatase reaction product, thus enabling the distribution of dying cells to be mapped. BEI is particularly useful in this context as it allows the examination of bulk specimens at …