Functionally essential interaction between Yersinia YscO and the T3S4 domain of YscP.

The type III secretion (T3S) system is essential to the virulence of a large number of Gram-negative bacterial pathogens, including Yersinia. YscO is required for T3S in Yersinia and is known to interact with several other T3S proteins, including the chaperone SycD and the needle length regulator YscP. To define which interactions of YscO are required for T3S, we pursued model-guided mutagenesis: three conserved and surface-exposed regions of modeled YscO were targeted for multiple alanine substitutions.

Structure and interactions of the cytoplasmic domain of the Yersinia type III secretion protein YscD.

The virulence of a large number of Gram-negative bacterial pathogens depends on the type III secretion (T3S) system, which transports select bacterial proteins into host cells. An essential component of the Yersinia T3S system is YscD, a single-pass inner membrane protein. We report here the 2.

A solvent-exposed patch in chaperone-bound YopE is required for translocation by the type III secretion system.

Most effector proteins of bacterial type III secretion (T3S) systems require chaperone proteins for translocation into host cells. Such effectors are bound by chaperones in a conserved and characteristic manner, with the chaperone-binding (Cb) region of the effector wound around the chaperone in a highly extended conformation. This conformation has been suggested to serve as a translocation signal in promoting the association between the chaperone-effector complex and a bacterial component required for translocation.

Starch biosynthesis: experiments on how starch granules grow in vivo.

Four varieties of starch granules from potato, wheat, maize, and rice were fractionated into homogeneous 10-microm-sized ranges. The size with the largest amount of granules was reacted with ADP-[(14)C]Glc, washed, and peeled into 7-9 layers, using a controlled peeling process, involving 90:10 volume proportions of Me(2)SO-H(2)O at 10 degrees C. All of the starches showed biosynthesis of starch throughout the granules.

Significant differences in the activities of alpha-amylases in the absence and presence of polyethylene glycol assayed on eight starches solubilized by two methods.

Starch is a reserve chemical source of the energy of the sun found in plants as a water-insoluble granule that differs in their chemical and physical properties, depending on the source. The granules can be solubilized by heating in water or by treatment with various reagents, such as 1M NaOH. alpha-Amylases are widely distributed enzymes that initiate the hydrolysis of starch into low molecular weight maltodextrins.

Controlled peeling of the surfaces of starch granules by gelatinization in aqueous dimethyl sulfoxide at selected temperatures.

Microscopic examination of starch granules in 90:10 (v/v) Me(2)SO-H(2)O indicated that the granules were slowly being gelatinized from their surfaces. The rate of gelatinization was dependent on two variables: (1) the amount of water in Me(2)SO and (2) the temperature. An increase of water in Me(2)SO and/or an increase in temperature increased the rate of gelatinization and vice versa.